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* mm: move call to compound_head() in release_pages()Ralph Campbell2020-10-141-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | The function is_huge_zero_page() doesn't call compound_head() to make sure the page pointer is a head page. The call to is_huge_zero_page() in release_pages() is made before compound_head() is called so the test would fail if release_pages() was called with a tail page of the huge_zero_page and put_page_testzero() would be called releasing the page. This is unlikely to be happening in normal use or we would be seeing all sorts of process data corruption when accessing a THP zero page. Looking at other places where is_huge_zero_page() is called, all seem to only pass a head page so I think the right solution is to move the call to compound_head() in release_pages() to a point before calling is_huge_zero_page(). Signed-off-by: Ralph Campbell <rcampbell@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Yu Zhao <yuzhao@google.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Christoph Hellwig <hch@lst.de> Link: https://lkml.kernel.org/r/20200917173938.16420-1-rcampbell@nvidia.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/swap.c: fix incomplete comment in lru_cache_add_inactive_or_unevictable()Miaohe Lin2020-10-141-3/+1
| | | | | | | | | | | | Since commit 9c4e6b1a7027 ("mm, mlock, vmscan: no more skipping pagevecs"), unevictable pages do not goes directly back onto zone's unevictable list. Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Shakeel Butt <shakeelb@google.com> Link: https://lkml.kernel.org/r/20200927122209.59328-1-linmiaohe@huawei.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/swap.c: fix confusing comment in release_pages()Miaohe Lin2020-10-141-1/+1
| | | | | | | | | | | | Since commit 07d802699528 ("mm: devmap: refactor 1-based refcounting for ZONE_DEVICE pages"), we have renamed the func put_devmap_managed_page() to page_is_devmap_managed(). Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: John Hubbard <jhubbard@nvidia.com> Link: https://lkml.kernel.org/r/20200905084453.19353-1-linmiaohe@huawei.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: remove superfluous __ClearPageActive()Yu Zhao2020-10-141-2/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | To activate a page, mark_page_accessed() always holds a reference on it. It either gets a new reference when adding a page to lru_pvecs.activate_page or reuses an existing one it previously got when it added a page to lru_pvecs.lru_add. So it doesn't call SetPageActive() on a page that doesn't have any reference left. Therefore, the race is impossible these days (I didn't brother to dig into its history). For other paths, namely reclaim and migration, a reference count is always held while calling SetPageActive() on a page. SetPageSlabPfmemalloc() also uses SetPageActive(), but it's irrelevant to LRU pages. Signed-off-by: Yu Zhao <yuzhao@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Yang Shi <shy828301@gmail.com> Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: Huang Ying <ying.huang@intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@suse.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Qian Cai <cai@lca.pw> Link: http://lkml.kernel.org/r/20200818184704.3625199-2-yuzhao@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: remove activate_page() from unuse_pte()Yu Zhao2020-10-141-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | We don't initially add anon pages to active lruvec after commit b518154e59aa ("mm/vmscan: protect the workingset on anonymous LRU"). Remove activate_page() from unuse_pte(), which seems to be missed by the commit. And make the function static while we are at it. Before the commit, we called lru_cache_add_active_or_unevictable() to add new ksm pages to active lruvec. Therefore, activate_page() wasn't necessary for them in the first place. Signed-off-by: Yu Zhao <yuzhao@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Yang Shi <shy828301@gmail.com> Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com> Cc: Huang Ying <ying.huang@intel.com> Cc: David Hildenbrand <david@redhat.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Qian Cai <cai@lca.pw> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Hugh Dickins <hughd@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Link: http://lkml.kernel.org/r/20200818184704.3625199-1-yuzhao@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Merge branch 'locking/urgent' into locking/core, to pick up fixesIngo Molnar2020-10-091-3/+3
|\ | | | | | | Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * mlock: fix unevictable_pgs event counts on THPHugh Dickins2020-09-191-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 5.8 commit 5d91f31faf8e ("mm: swap: fix vmstats for huge page") has established that vm_events should count every subpage of a THP, including unevictable_pgs_culled and unevictable_pgs_rescued; but lru_cache_add_inactive_or_unevictable() was not doing so for unevictable_pgs_mlocked, and mm/mlock.c was not doing so for unevictable_pgs mlocked, munlocked, cleared and stranded. Fix them; but THPs don't go the pagevec way in mlock.c, so no fixes needed on that path. Fixes: 5d91f31faf8e ("mm: swap: fix vmstats for huge page") Signed-off-by: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Yang Shi <shy828301@gmail.com> Cc: Alex Shi <alex.shi@linux.alibaba.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Qian Cai <cai@lca.pw> Link: http://lkml.kernel.org/r/alpine.LSU.2.11.2008301408230.5954@eggly.anvils Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | mm/swap: Do not abuse the seqcount_t latching APIAhmed S. Darwish2020-09-101-11/+54
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit eef1a429f234 ("mm/swap.c: piggyback lru_add_drain_all() calls") implemented an optimization mechanism to exit the to-be-started LRU drain operation (name it A) if another drain operation *started and finished* while (A) was blocked on the LRU draining mutex. This was done through a seqcount_t latch, which is an abuse of its semantics: 1. seqcount_t latching should be used for the purpose of switching between two storage places with sequence protection to allow interruptible, preemptible, writer sections. The referenced optimization mechanism has absolutely nothing to do with that. 2. The used raw_write_seqcount_latch() has two SMP write memory barriers to insure one consistent storage place out of the two storage places available. A full memory barrier is required instead: to guarantee that the pagevec counter stores visible by local CPU are visible to other CPUs -- before loading the current drain generation. Beside the seqcount_t API abuse, the semantics of a latch sequence counter was force-fitted into the referenced optimization. What was meant is to track "generations" of LRU draining operations, where "global lru draining generation = x" implies that all generations 0 < n <= x are already *scheduled* for draining -- thus nothing needs to be done if the current generation number n <= x. Remove the conceptually-inappropriate seqcount_t latch usage. Manually implement the referenced optimization using a counter and SMP memory barriers. Note, while at it, use the non-atomic variant of cpumask_set_cpu(), __cpumask_set_cpu(), due to the already existing mutex protection. Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/87y2pg9erj.fsf@vostro.fn.ogness.net
* mm/swap.c: annotate data races for lru_rotate_pvecsQian Cai2020-08-151-2/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Read to lru_add_pvec->nr could be interrupted and then write to the same variable. The write has local interrupt disabled, but the plain reads result in data races. However, it is unlikely the compilers could do much damage here given that lru_add_pvec->nr is a "unsigned char" and there is an existing compiler barrier. Thus, annotate the reads using the data_race() macro. The data races were reported by KCSAN, BUG: KCSAN: data-race in lru_add_drain_cpu / rotate_reclaimable_page write to 0xffff9291ebcb8a40 of 1 bytes by interrupt on cpu 23: rotate_reclaimable_page+0x2df/0x490 pagevec_add at include/linux/pagevec.h:81 (inlined by) rotate_reclaimable_page at mm/swap.c:259 end_page_writeback+0x1b5/0x2b0 end_swap_bio_write+0x1d0/0x280 bio_endio+0x297/0x560 dec_pending+0x218/0x430 [dm_mod] clone_endio+0xe4/0x2c0 [dm_mod] bio_endio+0x297/0x560 blk_update_request+0x201/0x920 scsi_end_request+0x6b/0x4a0 scsi_io_completion+0xb7/0x7e0 scsi_finish_command+0x1ed/0x2a0 scsi_softirq_done+0x1c9/0x1d0 blk_done_softirq+0x181/0x1d0 __do_softirq+0xd9/0x57c irq_exit+0xa2/0xc0 do_IRQ+0x8b/0x190 ret_from_intr+0x0/0x42 delay_tsc+0x46/0x80 __const_udelay+0x3c/0x40 __udelay+0x10/0x20 kcsan_setup_watchpoint+0x202/0x3a0 __tsan_read1+0xc2/0x100 lru_add_drain_cpu+0xb8/0x3f0 lru_add_drain+0x25/0x40 shrink_active_list+0xe1/0xc80 shrink_lruvec+0x766/0xb70 shrink_node+0x2d6/0xca0 do_try_to_free_pages+0x1f7/0x9a0 try_to_free_pages+0x252/0x5b0 __alloc_pages_slowpath+0x458/0x1290 __alloc_pages_nodemask+0x3bb/0x450 alloc_pages_vma+0x8a/0x2c0 do_anonymous_page+0x16e/0x6f0 __handle_mm_fault+0xcd5/0xd40 handle_mm_fault+0xfc/0x2f0 do_page_fault+0x263/0x6f9 page_fault+0x34/0x40 read to 0xffff9291ebcb8a40 of 1 bytes by task 37761 on cpu 23: lru_add_drain_cpu+0xb8/0x3f0 lru_add_drain_cpu at mm/swap.c:602 lru_add_drain+0x25/0x40 shrink_active_list+0xe1/0xc80 shrink_lruvec+0x766/0xb70 shrink_node+0x2d6/0xca0 do_try_to_free_pages+0x1f7/0x9a0 try_to_free_pages+0x252/0x5b0 __alloc_pages_slowpath+0x458/0x1290 __alloc_pages_nodemask+0x3bb/0x450 alloc_pages_vma+0x8a/0x2c0 do_anonymous_page+0x16e/0x6f0 __handle_mm_fault+0xcd5/0xd40 handle_mm_fault+0xfc/0x2f0 do_page_fault+0x263/0x6f9 page_fault+0x34/0x40 2 locks held by oom02/37761: #0: ffff9281e5928808 (&mm->mmap_sem#2){++++}, at: do_page_fault #1: ffffffffb3ade380 (fs_reclaim){+.+.}, at: fs_reclaim_acquire.part irq event stamp: 1949217 trace_hardirqs_on_thunk+0x1a/0x1c __do_softirq+0x2e7/0x57c __do_softirq+0x34c/0x57c irq_exit+0xa2/0xc0 Reported by Kernel Concurrency Sanitizer on: CPU: 23 PID: 37761 Comm: oom02 Not tainted 5.6.0-rc3-next-20200226+ #6 Hardware name: HP ProLiant BL660c Gen9, BIOS I38 10/17/2018 Signed-off-by: Qian Cai <cai@lca.pw> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Marco Elver <elver@google.com> Link: http://lkml.kernel.org/r/20200228044018.1263-1-cai@lca.pw Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: replace hpage_nr_pages with thp_nr_pagesMatthew Wilcox (Oracle)2020-08-151-8/+8
| | | | | | | | | | | | | | | | | The thp prefix is more frequently used than hpage and we should be consistent between the various functions. [akpm@linux-foundation.org: fix mm/migrate.c] Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: William Kucharski <william.kucharski@oracle.com> Reviewed-by: Zi Yan <ziy@nvidia.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: David Hildenbrand <david@redhat.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Link: http://lkml.kernel.org/r/20200629151959.15779-6-willy@infradead.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/vmscan: protect the workingset on anonymous LRUJoonsoo Kim2020-08-121-6/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In current implementation, newly created or swap-in anonymous page is started on active list. Growing active list results in rebalancing active/inactive list so old pages on active list are demoted to inactive list. Hence, the page on active list isn't protected at all. Following is an example of this situation. Assume that 50 hot pages on active list. Numbers denote the number of pages on active/inactive list (active | inactive). 1. 50 hot pages on active list 50(h) | 0 2. workload: 50 newly created (used-once) pages 50(uo) | 50(h) 3. workload: another 50 newly created (used-once) pages 50(uo) | 50(uo), swap-out 50(h) This patch tries to fix this issue. Like as file LRU, newly created or swap-in anonymous pages will be inserted to the inactive list. They are promoted to active list if enough reference happens. This simple modification changes the above example as following. 1. 50 hot pages on active list 50(h) | 0 2. workload: 50 newly created (used-once) pages 50(h) | 50(uo) 3. workload: another 50 newly created (used-once) pages 50(h) | 50(uo), swap-out 50(uo) As you can see, hot pages on active list would be protected. Note that, this implementation has a drawback that the page cannot be promoted and will be swapped-out if re-access interval is greater than the size of inactive list but less than the size of total(active+inactive). To solve this potential issue, following patch will apply workingset detection similar to the one that's already applied to file LRU. Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hugh Dickins <hughd@google.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Link: http://lkml.kernel.org/r/1595490560-15117-3-git-send-email-iamjoonsoo.kim@lge.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* treewide: Remove uninitialized_var() usageKees Cook2020-07-161-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Using uninitialized_var() is dangerous as it papers over real bugs[1] (or can in the future), and suppresses unrelated compiler warnings (e.g. "unused variable"). If the compiler thinks it is uninitialized, either simply initialize the variable or make compiler changes. In preparation for removing[2] the[3] macro[4], remove all remaining needless uses with the following script: git grep '\buninitialized_var\b' | cut -d: -f1 | sort -u | \ xargs perl -pi -e \ 's/\buninitialized_var\(([^\)]+)\)/\1/g; s:\s*/\* (GCC be quiet|to make compiler happy) \*/$::g;' drivers/video/fbdev/riva/riva_hw.c was manually tweaked to avoid pathological white-space. No outstanding warnings were found building allmodconfig with GCC 9.3.0 for x86_64, i386, arm64, arm, powerpc, powerpc64le, s390x, mips, sparc64, alpha, and m68k. [1] https://lore.kernel.org/lkml/20200603174714.192027-1-glider@google.com/ [2] https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/ [3] https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/ [4] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/ Reviewed-by: Leon Romanovsky <leonro@mellanox.com> # drivers/infiniband and mlx4/mlx5 Acked-by: Jason Gunthorpe <jgg@mellanox.com> # IB Acked-by: Kalle Valo <kvalo@codeaurora.org> # wireless drivers Reviewed-by: Chao Yu <yuchao0@huawei.com> # erofs Signed-off-by: Kees Cook <keescook@chromium.org>
* mm/swap: fix for "mm: workingset: age nonresident information alongside ↵Joonsoo Kim2020-06-261-2/+1
| | | | | | | | | | | | | | | | | | | | anonymous pages" Non-file-lru page could also be activated in mark_page_accessed() and we need to count this activation for nonresident_age. Note that it's better for this patch to be squashed into the patch "mm: workingset: age nonresident information alongside anonymous pages". Link: http://lkml.kernel.org/r/1592288204-27734-3-git-send-email-iamjoonsoo.kim@lge.com Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <js1304@gmail.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: swap: memcg: fix memcg stats for huge pagesShakeel Butt2020-06-041-5/+16
| | | | | | | | | | | | | | | The commit 2262185c5b28 ("mm: per-cgroup memory reclaim stats") added PGLAZYFREE, PGACTIVATE & PGDEACTIVATE stats for cgroups but missed couple of places and PGLAZYFREE missed huge page handling. Fix that. Also for PGLAZYFREE use the irq-unsafe function to update as the irq is already disabled. Fixes: 2262185c5b28 ("mm: per-cgroup memory reclaim stats") Signed-off-by: Shakeel Butt <shakeelb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Link: http://lkml.kernel.org/r/20200527182947.251343-1-shakeelb@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: swap: fix vmstats for huge pagesShakeel Butt2020-06-041-6/+8
| | | | | | | | | | | | | Many of the callbacks called by pagevec_lru_move_fn() does not correctly update the vmstats for huge pages. Fix that. Also __pagevec_lru_add_fn() use the irq-unsafe alternative to update the stat as the irqs are already disabled. Signed-off-by: Shakeel Butt <shakeelb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Link: http://lkml.kernel.org/r/20200527182916.249910-1-shakeelb@google.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: vmscan: reclaim writepage is IO costJohannes Weiner2020-06-041-6/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The VM tries to balance reclaim pressure between anon and file so as to reduce the amount of IO incurred due to the memory shortage. It already counts refaults and swapins, but in addition it should also count writepage calls during reclaim. For swap, this is obvious: it's IO that wouldn't have occurred if the anonymous memory hadn't been under memory pressure. From a relative balancing point of view this makes sense as well: even if anon is cold and reclaimable, a cache that isn't thrashing may have equally cold pages that don't require IO to reclaim. For file writeback, it's trickier: some of the reclaim writepage IO would have likely occurred anyway due to dirty expiration. But not all of it - premature writeback reduces batching and generates additional writes. Since the flushers are already woken up by the time the VM starts writing cache pages one by one, let's assume that we'e likely causing writes that wouldn't have happened without memory pressure. In addition, the per-page cost of IO would have probably been much cheaper if written in larger batches from the flusher thread rather than the single-page-writes from kswapd. For our purposes - getting the trend right to accelerate convergence on a stable state that doesn't require paging at all - this is sufficiently accurate. If we later wanted to optimize for sustained thrashing, we can still refine the measurements. Count all writepage calls from kswapd as IO cost toward the LRU that the page belongs to. Why do this dynamically? Don't we know in advance that anon pages require IO to reclaim, and so could build in a static bias? First, scanning is not the same as reclaiming. If all the anon pages are referenced, we may not swap for a while just because we're scanning the anon list. During this time, however, it's important that we age anonymous memory and the page cache at the same rate so that their hot-cold gradients are comparable. Everything else being equal, we still want to reclaim the coldest memory overall. Second, we keep copies in swap unless the page changes. If there is swap-backed data that's mostly read (tmpfs file) and has been swapped out before, we can reclaim it without incurring additional IO. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Link: http://lkml.kernel.org/r/20200520232525.798933-14-hannes@cmpxchg.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: vmscan: determine anon/file pressure balance at the reclaim rootJohannes Weiner2020-06-041-5/+27
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We split the LRU lists into anon and file, and we rebalance the scan pressure between them when one of them begins thrashing: if the file cache experiences workingset refaults, we increase the pressure on anonymous pages; if the workload is stalled on swapins, we increase the pressure on the file cache instead. With cgroups and their nested LRU lists, we currently don't do this correctly. While recursive cgroup reclaim establishes a relative LRU order among the pages of all involved cgroups, LRU pressure balancing is done on an individual cgroup LRU level. As a result, when one cgroup is thrashing on the filesystem cache while a sibling may have cold anonymous pages, pressure doesn't get equalized between them. This patch moves LRU balancing decision to the root of reclaim - the same level where the LRU order is established. It does this by tracking LRU cost recursively, so that every level of the cgroup tree knows the aggregate LRU cost of all memory within its domain. When the page scanner calculates the scan balance for any given individual cgroup's LRU list, it uses the values from the ancestor cgroup that initiated the reclaim cycle. If one sibling is then thrashing on the cache, it will tip the pressure balance inside its ancestors, and the next hierarchical reclaim iteration will go more after the anon pages in the tree. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Link: http://lkml.kernel.org/r/20200520232525.798933-13-hannes@cmpxchg.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: balance LRU lists based on relative thrashingJohannes Weiner2020-06-041-4/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Since the LRUs were split into anon and file lists, the VM has been balancing between page cache and anonymous pages based on per-list ratios of scanned vs. rotated pages. In most cases that tips page reclaim towards the list that is easier to reclaim and has the fewest actively used pages, but there are a few problems with it: 1. Refaults and LRU rotations are weighted the same way, even though one costs IO and the other costs a bit of CPU. 2. The less we scan an LRU list based on already observed rotations, the more we increase the sampling interval for new references, and rotations become even more likely on that list. This can enter a death spiral in which we stop looking at one list completely until the other one is all but annihilated by page reclaim. Since commit a528910e12ec ("mm: thrash detection-based file cache sizing") we have refault detection for the page cache. Along with swapin events, they are good indicators of when the file or anon list, respectively, is too small for its workingset and needs to grow. For example, if the page cache is thrashing, the cache pages need more time in memory, while there may be colder pages on the anonymous list. Likewise, if swapped pages are faulting back in, it indicates that we reclaim anonymous pages too aggressively and should back off. Replace LRU rotations with refaults and swapins as the basis for relative reclaim cost of the two LRUs. This will have the VM target list balances that incur the least amount of IO on aggregate. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Link: http://lkml.kernel.org/r/20200520232525.798933-12-hannes@cmpxchg.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: deactivations shouldn't bias the LRU balanceJohannes Weiner2020-06-041-6/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Operations like MADV_FREE, FADV_DONTNEED etc. currently move any affected active pages to the inactive list to accelerate their reclaim (good) but also steer page reclaim toward that LRU type, or away from the other (bad). The reason why this is undesirable is that such operations are not part of the regular page aging cycle, and rather a fluke that doesn't say much about the remaining pages on that list; they might all be in heavy use, and once the chunk of easy victims has been purged, the VM continues to apply elevated pressure on those remaining hot pages. The other LRU, meanwhile, might have easily reclaimable pages, and there was never a need to steer away from it in the first place. As the previous patch outlined, we should focus on recording actually observed cost to steer the balance rather than speculating about the potential value of one LRU list over the other. In that spirit, leave explicitely deactivated pages to the LRU algorithm to pick up, and let rotations decide which list is the easiest to reclaim. [cai@lca.pw: fix set-but-not-used warning] Link: http://lkml.kernel.org/r/20200522133335.GA624@Qians-MacBook-Air.local Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Minchan Kim <minchan@kernel.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Rik van Riel <riel@surriel.com> Cc: Qian Cai <cai@lca.pw> Link: http://lkml.kernel.org/r/20200520232525.798933-10-hannes@cmpxchg.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: base LRU balancing on an explicit cost modelJohannes Weiner2020-06-041-11/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, scan pressure between the anon and file LRU lists is balanced based on a mixture of reclaim efficiency and a somewhat vague notion of "value" of having certain pages in memory over others. That concept of value is problematic, because it has caused us to count any event that remotely makes one LRU list more or less preferrable for reclaim, even when these events are not directly comparable and impose very different costs on the system. One example is referenced file pages that we still deactivate and referenced anonymous pages that we actually rotate back to the head of the list. There is also conceptual overlap with the LRU algorithm itself. By rotating recently used pages instead of reclaiming them, the algorithm already biases the applied scan pressure based on page value. Thus, when rebalancing scan pressure due to rotations, we should think of reclaim cost, and leave assessing the page value to the LRU algorithm. Lastly, considering both value-increasing as well as value-decreasing events can sometimes cause the same type of event to be counted twice, i.e. how rotating a page increases the LRU value, while reclaiming it succesfully decreases the value. In itself this will balance out fine, but it quietly skews the impact of events that are only recorded once. The abstract metric of "value", the murky relationship with the LRU algorithm, and accounting both negative and positive events make the current pressure balancing model hard to reason about and modify. This patch switches to a balancing model of accounting the concrete, actually observed cost of reclaiming one LRU over another. For now, that cost includes pages that are scanned but rotated back to the list head. Subsequent patches will add consideration for IO caused by refaulting of recently evicted pages. Replace struct zone_reclaim_stat with two cost counters in the lruvec, and make everything that affects cost go through a new lru_note_cost() function. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@surriel.com> Link: http://lkml.kernel.org/r/20200520232525.798933-9-hannes@cmpxchg.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: remove use-once cache bias from LRU balancingJohannes Weiner2020-06-041-5/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | When the splitlru patches divided page cache and swap-backed pages into separate LRU lists, the pressure balance between the lists was biased to account for the fact that streaming IO can cause memory pressure with a flood of pages that are used only once. New page cache additions would tip the balance toward the file LRU, and repeat access would neutralize that bias again. This ensured that page reclaim would always go for used-once cache first. Since e9868505987a ("mm,vmscan: only evict file pages when we have plenty"), page reclaim generally skips over swap-backed memory entirely as long as there is used-once cache present, and will apply the LRU balancing when only repeatedly accessed cache pages are left - at which point the previous use-once bias will have been neutralized. This makes the use-once cache balancing bias unnecessary. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Minchan Kim <minchan@kernel.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Rik van Riel <riel@surriel.com> Link: http://lkml.kernel.org/r/20200520232525.798933-7-hannes@cmpxchg.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: fold and remove lru_cache_add_anon() and lru_cache_add_file()Johannes Weiner2020-06-041-32/+10
| | | | | | | | | | | | | | | They're the same function, and for the purpose of all callers they are equivalent to lru_cache_add(). [akpm@linux-foundation.org: fix it for local_lock changes] Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Rik van Riel <riel@surriel.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Minchan Kim <minchan@kernel.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Link: http://lkml.kernel.org/r/20200520232525.798933-5-hannes@cmpxchg.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: fix LRU balancing effect of new transparent huge pagesJohannes Weiner2020-06-041-14/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The reclaim code that balances between swapping and cache reclaim tries to predict likely reuse based on in-memory reference patterns alone. This works in many cases, but when it fails it cannot detect when the cache is thrashing pathologically, or when we're in the middle of a swap storm. The high seek cost of rotational drives under which the algorithm evolved also meant that mistakes could quickly result in lockups from too aggressive swapping (which is predominantly random IO). As a result, the balancing code has been tuned over time to a point where it mostly goes for page cache and defers swapping until the VM is under significant memory pressure. The resulting strategy doesn't make optimal caching decisions - where optimal is the least amount of IO required to execute the workload. The proliferation of fast random IO devices such as SSDs, in-memory compression such as zswap, and persistent memory technologies on the horizon, has made this undesirable behavior very noticable: Even in the presence of large amounts of cold anonymous memory and a capable swap device, the VM refuses to even seriously scan these pages, and can leave the page cache thrashing needlessly. This series sets out to address this. Since commit ("a528910e12ec mm: thrash detection-based file cache sizing") we have exact tracking of refault IO - the ultimate cost of reclaiming the wrong pages. This allows us to use an IO cost based balancing model that is more aggressive about scanning anonymous memory when the cache is thrashing, while being able to avoid unnecessary swap storms. These patches base the LRU balance on the rate of refaults on each list, times the relative IO cost between swap device and filesystem (swappiness), in order to optimize reclaim for least IO cost incurred. History I floated these changes in 2016. At the time they were incomplete and full of workarounds due to a lack of infrastructure in the reclaim code: We didn't have PageWorkingset, we didn't have hierarchical cgroup statistics, and problems with the cgroup swap controller. As swapping wasn't too high a priority then, the patches stalled out. With all dependencies in place now, here we are again with much cleaner, feature-complete patches. I kept the acks for patches that stayed materially the same :-) Below is a series of test results that demonstrate certain problematic behavior of the current code, as well as showcase the new code's more predictable and appropriate balancing decisions. Test #1: No convergence This test shows an edge case where the VM currently doesn't converge at all on a new file workingset with a stale anon/tmpfs set. The test sets up a cold anon set the size of 3/4 RAM, then tries to establish a new file set half the size of RAM (flat access pattern). The vanilla kernel refuses to even scan anon pages and never converges. The file set is perpetually served from the filesystem. The first test kernel is with the series up to the workingset patch applied. This allows thrashing page cache to challenge the anonymous workingset. The VM then scans the lists based on the current scanned/rotated balancing algorithm. It converges on a stable state where all cold anon pages are pushed out and the fileset is served entirely from cache: noconverge/5.7-rc5-mm noconverge/5.7-rc5-mm-workingset Scanned 417719308.00 ( +0.00%) 64091155.00 ( -84.66%) Reclaimed 417711094.00 ( +0.00%) 61640308.00 ( -85.24%) Reclaim efficiency % 100.00 ( +0.00%) 96.18 ( -3.78%) Scanned file 417719308.00 ( +0.00%) 59211118.00 ( -85.83%) Scanned anon 0.00 ( +0.00%) 4880037.00 ( ) Swapouts 0.00 ( +0.00%) 2439957.00 ( ) Swapins 0.00 ( +0.00%) 257.00 ( ) Refaults 415246605.00 ( +0.00%) 59183722.00 ( -85.75%) Restore refaults 0.00 ( +0.00%) 54988252.00 ( ) The second test kernel is with the full patch series applied, which replaces the scanned/rotated ratios with refault/swapin rate-based balancing. It evicts the cold anon pages more aggressively in the presence of a thrashing cache and the absence of swapins, and so converges with about 60% of the IO and reclaim activity: noconverge/5.7-rc5-mm-workingset noconverge/5.7-rc5-mm-lrubalance Scanned 64091155.00 ( +0.00%) 37579741.00 ( -41.37%) Reclaimed 61640308.00 ( +0.00%) 35129293.00 ( -43.01%) Reclaim efficiency % 96.18 ( +0.00%) 93.48 ( -2.78%) Scanned file 59211118.00 ( +0.00%) 32708385.00 ( -44.76%) Scanned anon 4880037.00 ( +0.00%) 4871356.00 ( -0.18%) Swapouts 2439957.00 ( +0.00%) 2435565.00 ( -0.18%) Swapins 257.00 ( +0.00%) 262.00 ( +1.94%) Refaults 59183722.00 ( +0.00%) 32675667.00 ( -44.79%) Restore refaults 54988252.00 ( +0.00%) 28480430.00 ( -48.21%) We're triggering this case in host sideloading scenarios: When a host's primary workload is not saturating the machine (primary load is usually driven by user activity), we can optimistically sideload a batch job; if user activity picks up and the primary workload needs the whole host during this time, we freeze the sideload and rely on it getting pushed to swap. Frequently that swapping doesn't happen and the completely inactive sideload simply stays resident while the expanding primary worklad is struggling to gain ground. Test #2: Kernel build This test is a a kernel build that is slightly memory-restricted (make -j4 inside a 400M cgroup). Despite the very aggressive swapping of cold anon pages in test #1, this test shows that the new kernel carefully balances swap against cache refaults when both the file and the cache set are pressured. It shows the patched kernel to be slightly better at finding the coldest memory from the combined anon and file set to evict under pressure. The result is lower aggregate reclaim and paging activity: z 5.7-rc5-mm 5.7-rc5-mm-lrubalance Real time 210.60 ( +0.00%) 210.97 ( +0.18%) User time 745.42 ( +0.00%) 746.48 ( +0.14%) System time 69.78 ( +0.00%) 69.79 ( +0.02%) Scanned file 354682.00 ( +0.00%) 293661.00 ( -17.20%) Scanned anon 465381.00 ( +0.00%) 378144.00 ( -18.75%) Swapouts 185920.00 ( +0.00%) 147801.00 ( -20.50%) Swapins 34583.00 ( +0.00%) 32491.00 ( -6.05%) Refaults 212664.00 ( +0.00%) 172409.00 ( -18.93%) Restore refaults 48861.00 ( +0.00%) 80091.00 ( +63.91%) Total paging IO 433167.00 ( +0.00%) 352701.00 ( -18.58%) Test #3: Overload This next test is not about performance, but rather about the predictability of the algorithm. The current balancing behavior doesn't always lead to comprehensible results, which makes performance analysis and parameter tuning (swappiness e.g.) very difficult. The test shows the balancing behavior under equivalent anon and file input. Anon and file sets are created of equal size (3/4 RAM), have the same access patterns (a hot-cold gradient), and synchronized access rates. Swappiness is raised from the default of 60 to 100 to indicate equal IO cost between swap and cache. With the vanilla balancing code, anon scans make up around 9% of the total pages scanned, or a ~1:10 ratio. This is a surprisingly skewed ratio, and it's an outcome that is hard to explain given the input parameters to the VM. The new balancing model targets a 1:2 balance: All else being equal, reclaiming a file page costs one page IO - the refault; reclaiming an anon page costs two IOs - the swapout and the swapin. In the test we observe a ~1:3 balance. The scanned and paging IO numbers indicate that the anon LRU algorithm we have in place right now does a slightly worse job at picking the coldest pages compared to the file algorithm. There is ongoing work to improve this, like Joonsoo's anon workingset patches; however, it's difficult to compare the two aging strategies when the balancing between them is behaving unintuitively. The slightly less efficient anon reclaim results in a deviation from the optimal 1:2 scan ratio we would like to see here - however, 1:3 is much closer to what we'd want to see in this test than the vanilla kernel's aging of 10+ cache pages for every anonymous one: overload-100/5.7-rc5-mm-workingset overload-100/5.7-rc5-mm-lrubalance-realfile Scanned 533633725.00 ( +0.00%) 595687785.00 ( +11.63%) Reclaimed 494325440.00 ( +0.00%) 518154380.00 ( +4.82%) Reclaim efficiency % 92.63 ( +0.00%) 86.98 ( -6.03%) Scanned file 484532894.00 ( +0.00%) 456937722.00 ( -5.70%) Scanned anon 49100831.00 ( +0.00%) 138750063.00 ( +182.58%) Swapouts 8096423.00 ( +0.00%) 48982142.00 ( +504.98%) Swapins 10027384.00 ( +0.00%) 62325044.00 ( +521.55%) Refaults 479819973.00 ( +0.00%) 451309483.00 ( -5.94%) Restore refaults 426422087.00 ( +0.00%) 399914067.00 ( -6.22%) Total paging IO 497943780.00 ( +0.00%) 562616669.00 ( +12.99%) Test #4: Parallel IO It's important to note that these patches only affect the situation where the kernel has to reclaim workingset memory, which is usually a transitionary period. The vast majority of page reclaim occuring in a system is from trimming the ever-expanding page cache. These patches don't affect cache trimming behavior. We never swap as long as we only have use-once cache moving through the file LRU, we only consider swapping when the cache is actively thrashing. The following test demonstrates this. It has an anon workingset that takes up half of RAM and then writes a file that is twice the size of RAM out to disk. As the cache is funneled through the inactive file list, no anon pages are scanned (aside from apparently some background noise of 10 pages): 5.7-rc5-mm 5.7-rc5-mm-lrubalance Scanned 10714722.00 ( +0.00%) 10723445.00 ( +0.08%) Reclaimed 10703596.00 ( +0.00%) 10712166.00 ( +0.08%) Reclaim efficiency % 99.90 ( +0.00%) 99.89 ( -0.00%) Scanned file 10714722.00 ( +0.00%) 10723435.00 ( +0.08%) Scanned anon 0.00 ( +0.00%) 10.00 ( ) Swapouts 0.00 ( +0.00%) 7.00 ( ) Swapins 0.00 ( +0.00%) 0.00 ( +0.00%) Refaults 92.00 ( +0.00%) 41.00 ( -54.84%) Restore refaults 0.00 ( +0.00%) 0.00 ( +0.00%) Total paging IO 92.00 ( +0.00%) 48.00 ( -47.31%) This patch (of 14): Currently, THP are counted as single pages until they are split right before being swapped out. However, at that point the VM is already in the middle of reclaim, and adjusting the LRU balance then is useless. Always account THP by the number of basepages, and remove the fixup from the splitting path. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Shakeel Butt <shakeelb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Rik van Riel <riel@surriel.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Minchan Kim <minchan@kernel.org> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Link: http://lkml.kernel.org/r/20200520232525.798933-1-hannes@cmpxchg.org Link: http://lkml.kernel.org/r/20200520232525.798933-2-hannes@cmpxchg.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: simplify calling a compound page destructorMatthew Wilcox (Oracle)2020-06-041-4/+1
| | | | | | | | | | | | | | None of the three callers of get_compound_page_dtor() want to know the value; they just want to call the function. Replace it with destroy_compound_page() which calls the dtor for them. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com> Reviewed-by: David Hildenbrand <david@redhat.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Link: http://lkml.kernel.org/r/20200517105051.9352-1-willy@infradead.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/swap: Use local_lock for protectionIngo Molnar2020-05-281-38/+80
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The various struct pagevec per CPU variables are protected by disabling either preemption or interrupts across the critical sections. Inside these sections spinlocks have to be acquired. These spinlocks are regular spinlock_t types which are converted to "sleeping" spinlocks on PREEMPT_RT enabled kernels. Obviously sleeping locks cannot be acquired in preemption or interrupt disabled sections. local locks provide a trivial way to substitute preempt and interrupt disable instances. On a non PREEMPT_RT enabled kernel local_lock() maps to preempt_disable() and local_lock_irq() to local_irq_disable(). Create lru_rotate_pvecs containing the pagevec and the locallock. Create lru_pvecs containing the remaining pagevecs and the locallock. Add lru_add_drain_cpu_zone() which is used from compact_zone() to avoid exporting the pvec structure. Change the relevant call sites to acquire these locks instead of using preempt_disable() / get_cpu() / get_cpu_var() and local_irq_disable() / local_irq_save(). There is neither a functional change nor a change in the generated binary code for non PREEMPT_RT enabled non-debug kernels. When lockdep is enabled local locks have lockdep maps embedded. These allow lockdep to validate the protections, i.e. inappropriate usage of a preemption only protected sections would result in a lockdep warning while the same problem would not be noticed with a plain preempt_disable() based protection. local locks also improve readability as they provide a named scope for the protections while preempt/interrupt disable are opaque scopeless. Finally local locks allow PREEMPT_RT to substitute them with real locking primitives to ensure the correctness of operation in a fully preemptible kernel. [ bigeasy: Adopted to use local_lock ] Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Acked-by: Peter Zijlstra <peterz@infradead.org> Link: https://lore.kernel.org/r/20200527201119.1692513-4-bigeasy@linutronix.de
* mm: huge tmpfs: try to split_huge_page() when punching holeHugh Dickins2020-04-071-0/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Yang Shi writes: Currently, when truncating a shmem file, if the range is partly in a THP (start or end is in the middle of THP), the pages actually will just get cleared rather than being freed, unless the range covers the whole THP. Even though all the subpages are truncated (randomly or sequentially), the THP may still be kept in page cache. This might be fine for some usecases which prefer preserving THP, but balloon inflation is handled in base page size. So when using shmem THP as memory backend, QEMU inflation actually doesn't work as expected since it doesn't free memory. But the inflation usecase really needs to get the memory freed. (Anonymous THP will also not get freed right away, but will be freed eventually when all subpages are unmapped: whereas shmem THP still stays in page cache.) Split THP right away when doing partial hole punch, and if split fails just clear the page so that read of the punched area will return zeroes. Hugh Dickins adds: Our earlier "team of pages" huge tmpfs implementation worked in the way that Yang Shi proposes; and we have been using this patch to continue to split the huge page when hole-punched or truncated, since converting over to the compound page implementation. Although huge tmpfs gives out huge pages when available, if the user specifically asks to truncate or punch a hole (perhaps to free memory, perhaps to reduce the memcg charge), then the filesystem should do so as best it can, splitting the huge page. That is not always possible: any additional reference to the huge page prevents split_huge_page() from succeeding, so the result can be flaky. But in practice it works successfully enough that we've not seen any problem from that. Add shmem_punch_compound() to encapsulate the decision of when a split is needed, and doing the split if so. Using this simplifies the flow in shmem_undo_range(); and the first (trylock) pass does not need to do any page clearing on failure, because the second pass will either succeed or do that clearing. Following the example of zero_user_segment() when clearing a partial page, add flush_dcache_page() and set_page_dirty() when clearing a hole - though I'm not certain that either is needed. But: split_huge_page() would be sure to fail if shmem_undo_range()'s pagevec holds further references to the huge page. The easiest way to fix that is for find_get_entries() to return early, as soon as it has put one compound head or tail into the pagevec. At first this felt like a hack; but on examination, this convention better suits all its callers - or will do, if the slight one-page-per-pagevec slowdown in shmem_unlock_mapping() and shmem_seek_hole_data() is transformed into a 512-page-per-pagevec speedup by checking for compound pages there. Signed-off-by: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Yang Shi <yang.shi@linux.alibaba.com> Cc: Alexander Duyck <alexander.duyck@gmail.com> Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: David Hildenbrand <david@redhat.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Link: http://lkml.kernel.org/r/alpine.LSU.2.11.2002261959020.10801@eggly.anvils Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: code cleanup for MADV_FREEHuang Ying2020-04-071-8/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | Some comments for MADV_FREE is revised and added to help people understand the MADV_FREE code, especially the page flag, PG_swapbacked. This makes page_is_file_cache() isn't consistent with its comments. So the function is renamed to page_is_file_lru() to make them consistent again. All these are put in one patch as one logical change. Suggested-by: David Hildenbrand <david@redhat.com> Suggested-by: Johannes Weiner <hannes@cmpxchg.org> Suggested-by: David Rientjes <rientjes@google.com> Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: David Rientjes <rientjes@google.com> Acked-by: Michal Hocko <mhocko@kernel.org> Acked-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Minchan Kim <minchan@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@surriel.com> Link: http://lkml.kernel.org/r/20200317100342.2730705-1-ying.huang@intel.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: swap: use smp_mb__after_atomic() to order LRU bit setYang Shi2020-04-021-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | Memory barrier is needed after setting LRU bit, but smp_mb() is too strong. Some architectures, i.e. x86, imply memory barrier with atomic operations, so replacing it with smp_mb__after_atomic() sounds better, which is nop on strong ordered machines, and full memory barriers on others. With this change the vm-scalability cases would perform better on x86, I saw total 6% improvement with this patch and previous inline fix. The test data (lru-file-readtwice throughput) against v5.6-rc4: mainline w/ inline fix w/ both (adding this) 150MB 154MB 159MB Fixes: 9c4e6b1a7027 ("mm, mlock, vmscan: no more skipping pagevecs") Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Shakeel Butt <shakeelb@google.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Link: http://lkml.kernel.org/r/1584500541-46817-2-git-send-email-yang.shi@linux.alibaba.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/swap.c: not necessary to export __pagevec_lru_add()Wei Yang2020-04-021-1/+0
| | | | | | | | | | | | __pagevec_lru_add() is only used in mm directory now. Remove the export symbol. Signed-off-by: Wei Yang <richardw.yang@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/20200126011436.22979-1-richardw.yang@linux.intel.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: devmap: refactor 1-based refcounting for ZONE_DEVICE pagesJohn Hubbard2020-01-311-1/+26
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | An upcoming patch changes and complicates the refcounting and especially the "put page" aspects of it. In order to keep everything clean, refactor the devmap page release routines: * Rename put_devmap_managed_page() to page_is_devmap_managed(), and limit the functionality to "read only": return a bool, with no side effects. * Add a new routine, put_devmap_managed_page(), to handle decrementing the refcount for ZONE_DEVICE pages. * Change callers (just release_pages() and put_page()) to check page_is_devmap_managed() before calling the new put_devmap_managed_page() routine. This is a performance point: put_page() is a hot path, so we need to avoid non- inline function calls where possible. * Rename __put_devmap_managed_page() to free_devmap_managed_page(), and limit the functionality to unconditionally freeing a devmap page. This is originally based on a separate patch by Ira Weiny, which applied to an early version of the put_user_page() experiments. Since then, Jérôme Glisse suggested the refactoring described above. Link: http://lkml.kernel.org/r/20200107224558.2362728-5-jhubbard@nvidia.com Signed-off-by: Ira Weiny <ira.weiny@intel.com> Signed-off-by: John Hubbard <jhubbard@nvidia.com> Suggested-by: Jérôme Glisse <jglisse@redhat.com> Reviewed-by: Dan Williams <dan.j.williams@intel.com> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Christoph Hellwig <hch@lst.de> Cc: Kirill A. Shutemov <kirill@shutemov.name> Cc: Alex Williamson <alex.williamson@redhat.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Björn Töpel <bjorn.topel@intel.com> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Hans Verkuil <hverkuil-cisco@xs4all.nl> Cc: Jason Gunthorpe <jgg@mellanox.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Leon Romanovsky <leonro@mellanox.com> Cc: Mauro Carvalho Chehab <mchehab@kernel.org> Cc: Mike Rapoport <rppt@linux.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/swap.c: piggyback lru_add_drain_all() callsKonstantin Khlebnikov2019-12-011-1/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This is a very slow operation. Right now POSIX_FADV_DONTNEED is the top user because it has to freeze page references when removing it from the cache. invalidate_bdev() calls it for the same reason. Both are triggered from userspace, so it's easy to generate a storm. mlock/mlockall no longer calls lru_add_drain_all - I've seen here serious slowdown on older kernels. There are some less obvious paths in memory migration/CMA/offlining which shouldn't call frequently. The worst case requires a non-trivial workload because lru_add_drain_all() skips cpus where vectors are empty. Something must constantly generate a flow of pages for each cpu. Also cpus must be busy to make scheduling per-cpu works slower. And the machine must be big enough (64+ cpus in our case). In our case that was a massive series of mlock calls in map-reduce while other tasks write logs (and generates flows of new pages in per-cpu vectors). Mlock calls were serialized by mutex and accumulated latency up to 10 seconds or more. The kernel does not call lru_add_drain_all on mlock paths since 4.15, but the same scenario could be triggered by fadvise(POSIX_FADV_DONTNEED) or any other remaining user. There is no reason to do the drain again if somebody else already drained all the per-cpu vectors while we waited for the lock. Piggyback on a drain starting and finishing while we wait for the lock: all pages pending at the time of our entry were drained from the vectors. Callers like POSIX_FADV_DONTNEED retry their operations once after draining per-cpu vectors when pages have unexpected references. Link: http://lkml.kernel.org/r/157019456205.3142.3369423180908482020.stgit@buzz Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Matthew Wilcox <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/swap.c: trivial mark_page_accessed() cleanupFengguang Wu2019-12-011-4/+9
| | | | | | | | | | | | | This avoids duplicated PageReferenced() calls. No behavior change. Link: http://lkml.kernel.org/r/20191016225326.GB12497@wfg-t540p.sh.intel.com Signed-off-by: Fengguang Wu <fengguang.wu@intel.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Liu Jingqi <jingqi.liu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: introduce MADV_COLDMinchan Kim2019-09-261-0/+42
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Patch series "Introduce MADV_COLD and MADV_PAGEOUT", v7. - Background The Android terminology used for forking a new process and starting an app from scratch is a cold start, while resuming an existing app is a hot start. While we continually try to improve the performance of cold starts, hot starts will always be significantly less power hungry as well as faster so we are trying to make hot start more likely than cold start. To increase hot start, Android userspace manages the order that apps should be killed in a process called ActivityManagerService. ActivityManagerService tracks every Android app or service that the user could be interacting with at any time and translates that into a ranked list for lmkd(low memory killer daemon). They are likely to be killed by lmkd if the system has to reclaim memory. In that sense they are similar to entries in any other cache. Those apps are kept alive for opportunistic performance improvements but those performance improvements will vary based on the memory requirements of individual workloads. - Problem Naturally, cached apps were dominant consumers of memory on the system. However, they were not significant consumers of swap even though they are good candidate for swap. Under investigation, swapping out only begins once the low zone watermark is hit and kswapd wakes up, but the overall allocation rate in the system might trip lmkd thresholds and cause a cached process to be killed(we measured performance swapping out vs. zapping the memory by killing a process. Unsurprisingly, zapping is 10x times faster even though we use zram which is much faster than real storage) so kill from lmkd will often satisfy the high zone watermark, resulting in very few pages actually being moved to swap. - Approach The approach we chose was to use a new interface to allow userspace to proactively reclaim entire processes by leveraging platform information. This allowed us to bypass the inaccuracy of the kernel’s LRUs for pages that are known to be cold from userspace and to avoid races with lmkd by reclaiming apps as soon as they entered the cached state. Additionally, it could provide many chances for platform to use much information to optimize memory efficiency. To achieve the goal, the patchset introduce two new options for madvise. One is MADV_COLD which will deactivate activated pages and the other is MADV_PAGEOUT which will reclaim private pages instantly. These new options complement MADV_DONTNEED and MADV_FREE by adding non-destructive ways to gain some free memory space. MADV_PAGEOUT is similar to MADV_DONTNEED in a way that it hints the kernel that memory region is not currently needed and should be reclaimed immediately; MADV_COLD is similar to MADV_FREE in a way that it hints the kernel that memory region is not currently needed and should be reclaimed when memory pressure rises. This patch (of 5): When a process expects no accesses to a certain memory range, it could give a hint to kernel that the pages can be reclaimed when memory pressure happens but data should be preserved for future use. This could reduce workingset eviction so it ends up increasing performance. This patch introduces the new MADV_COLD hint to madvise(2) syscall. MADV_COLD can be used by a process to mark a memory range as not expected to be used in the near future. The hint can help kernel in deciding which pages to evict early during memory pressure. It works for every LRU pages like MADV_[DONTNEED|FREE]. IOW, It moves active file page -> inactive file LRU active anon page -> inacdtive anon LRU Unlike MADV_FREE, it doesn't move active anonymous pages to inactive file LRU's head because MADV_COLD is a little bit different symantic. MADV_FREE means it's okay to discard when the memory pressure because the content of the page is *garbage* so freeing such pages is almost zero overhead since we don't need to swap out and access afterward causes just minor fault. Thus, it would make sense to put those freeable pages in inactive file LRU to compete other used-once pages. It makes sense for implmentaion point of view, too because it's not swapbacked memory any longer until it would be re-dirtied. Even, it could give a bonus to make them be reclaimed on swapless system. However, MADV_COLD doesn't mean garbage so reclaiming them requires swap-out/in in the end so it's bigger cost. Since we have designed VM LRU aging based on cost-model, anonymous cold pages would be better to position inactive anon's LRU list, not file LRU. Furthermore, it would help to avoid unnecessary scanning if system doesn't have a swap device. Let's start simpler way without adding complexity at this moment. However, keep in mind, too that it's a caveat that workloads with a lot of pages cache are likely to ignore MADV_COLD on anonymous memory because we rarely age anonymous LRU lists. * man-page material MADV_COLD (since Linux x.x) Pages in the specified regions will be treated as less-recently-accessed compared to pages in the system with similar access frequencies. In contrast to MADV_FREE, the contents of the region are preserved regardless of subsequent writes to pages. MADV_COLD cannot be applied to locked pages, Huge TLB pages, or VM_PFNMAP pages. [akpm@linux-foundation.org: resolve conflicts with hmm.git] Link: http://lkml.kernel.org/r/20190726023435.214162-2-minchan@kernel.org Signed-off-by: Minchan Kim <minchan@kernel.org> Reported-by: kbuild test robot <lkp@intel.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: James E.J. Bottomley <James.Bottomley@HansenPartnership.com> Cc: Richard Henderson <rth@twiddle.net> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Chris Zankel <chris@zankel.net> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Daniel Colascione <dancol@google.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Hillf Danton <hdanton@sina.com> Cc: Joel Fernandes (Google) <joel@joelfernandes.org> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Oleksandr Natalenko <oleksandr@redhat.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Sonny Rao <sonnyrao@google.com> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Tim Murray <timmurray@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: move mem_cgroup_uncharge out of __page_cache_release()Yang Shi2019-09-251-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | A later patch makes THP deferred split shrinker memcg aware, but it needs page->mem_cgroup information in THP destructor, which is called after mem_cgroup_uncharge() now. So move mem_cgroup_uncharge() from __page_cache_release() to compound page destructor, which is called by both THP and other compound pages except HugeTLB. And call it in __put_single_page() for single order page. Link: http://lkml.kernel.org/r/1565144277-36240-3-git-send-email-yang.shi@linux.alibaba.com Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com> Suggested-by: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Hugh Dickins <hughd@google.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: David Rientjes <rientjes@google.com> Cc: Qian Cai <cai@lca.pw> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: replace list_move_tail() with add_page_to_lru_list_tail()Yu Zhao2019-09-251-8/+6
| | | | | | | | | | | | | | | | This is a cleanup patch that replaces two historical uses of list_move_tail() with relatively recent add_page_to_lru_list_tail(). Link: http://lkml.kernel.org/r/20190716212436.7137-1-yuzhao@google.com Signed-off-by: Yu Zhao <yuzhao@google.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Michal Hocko <mhocko@suse.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Ira Weiny <ira.weiny@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* docs: admin-guide: move sysctl directory to itMauro Carvalho Chehab2019-07-151-1/+1
| | | | | | | | The stuff under sysctl describes /sys interface from userspace point of view. So, add it to the admin-guide and remove the :orphan: from its index file. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
* docs: sysctl: convert to ReSTMauro Carvalho Chehab2019-07-151-1/+1
| | | | | | | | | | | | | | | | | Rename the /proc/sys/ documentation files to ReST, using the README file as a template for an index.rst, adding the other files there via TOC markup. Despite being written on different times with different styles, try to make them somewhat coherent with a similar look and feel, ensuring that they'll look nice as both raw text file and as via the html output produced by the Sphinx build system. At its new index.rst, let's add a :orphan: while this is not linked to the main index.rst file, in order to avoid build warnings. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
* mm/swap: fix release_pages() when releasing devmap pagesIra Weiny2019-07-021-4/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | release_pages() is an optimized version of a loop around put_page(). Unfortunately for devmap pages the logic is not entirely correct in release_pages(). This is because device pages can be more than type MEMORY_DEVICE_PUBLIC. There are in fact 4 types, private, public, FS DAX, and PCI P2PDMA. Some of these have specific needs to "put" the page while others do not. This logic to handle any special needs is contained in put_devmap_managed_page(). Therefore all devmap pages should be processed by this function where we can contain the correct logic for a page put. Handle all device type pages within release_pages() by calling put_devmap_managed_page() on all devmap pages. If put_devmap_managed_page() returns true the page has been put and we continue with the next page. A false return of put_devmap_managed_page() means the page did not require special processing and should fall to "normal" processing. This was found via code inspection while determining if release_pages() and the new put_user_pages() could be interchangeable.[1] [1] https://lkml.kernel.org/r/20190523172852.GA27175@iweiny-DESK2.sc.intel.com Link: https://lkml.kernel.org/r/20190605214922.17684-1-ira.weiny@intel.com Cc: Jérôme Glisse <jglisse@redhat.com> Cc: Michal Hocko <mhocko@suse.com> Reviewed-by: Dan Williams <dan.j.williams@intel.com> Reviewed-by: John Hubbard <jhubbard@nvidia.com> Signed-off-by: Ira Weiny <ira.weiny@intel.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* treewide: Add SPDX license identifier for missed filesThomas Gleixner2019-05-211-0/+1
| | | | | | | | | | | | | | | | | Add SPDX license identifiers to all files which: - Have no license information of any form - Have EXPORT_.*_SYMBOL_GPL inside which was used in the initial scan/conversion to ignore the file These files fall under the project license, GPL v2 only. The resulting SPDX license identifier is: GPL-2.0-only Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* mm/swap.c: __pagevec_lru_add_fn: typo fixPeng Fan2019-05-141-1/+1
| | | | | | | | | | | | | There is no function named munlock_vma_pages(). Correct it to munlock_vma_page(). Link: http://lkml.kernel.org/r/20190402095609.27181-1-peng.fan@nxp.com Signed-off-by: Peng Fan <peng.fan@nxp.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Mukesh Ojha <mojha@codeaurora.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: remove zone_lru_lock() function, access ->lru_lock directlyAndrey Ryabinin2019-03-061-8/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | We have common pattern to access lru_lock from a page pointer: zone_lru_lock(page_zone(page)) Which is silly, because it unfolds to this: &NODE_DATA(page_to_nid(page))->node_zones[page_zonenum(page)]->zone_pgdat->lru_lock while we can simply do &NODE_DATA(page_to_nid(page))->lru_lock Remove zone_lru_lock() function, since it's only complicate things. Use 'page_pgdat(page)->lru_lock' pattern instead. [aryabinin@virtuozzo.com: a slightly better version of __split_huge_page()] Link: http://lkml.kernel.org/r/20190301121651.7741-1-aryabinin@virtuozzo.com Link: http://lkml.kernel.org/r/20190228083329.31892-2-aryabinin@virtuozzo.com Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Mel Gorman <mgorman@techsingularity.net> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Rik van Riel <riel@surriel.com> Cc: William Kucharski <william.kucharski@oracle.com> Cc: John Hubbard <jhubbard@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: handle lru_add_drain_all for UP properlyMichal Hocko2019-02-211-7/+10
| | | | | | | | | | | | | | | | | | | | | | | | | Since for_each_cpu(cpu, mask) added by commit 2d3854a37e8b767a ("cpumask: introduce new API, without changing anything") did not evaluate the mask argument if NR_CPUS == 1 due to CONFIG_SMP=n, lru_add_drain_all() is hitting WARN_ON() at __flush_work() added by commit 4d43d395fed12463 ("workqueue: Try to catch flush_work() without INIT_WORK().") by unconditionally calling flush_work() [1]. Workaround this issue by using CONFIG_SMP=n specific lru_add_drain_all implementation. There is no real need to defer the implementation to the workqueue as the draining is going to happen on the local cpu. So alias lru_add_drain_all to lru_add_drain which does all the necessary work. [akpm@linux-foundation.org: fix various build warnings] [1] https://lkml.kernel.org/r/18a30387-6aa5-6123-e67c-57579ecc3f38@roeck-us.net Link: http://lkml.kernel.org/r/20190213124334.GH4525@dhcp22.suse.cz Signed-off-by: Michal Hocko <mhocko@suse.com> Reported-by: Guenter Roeck <linux@roeck-us.net> Debugged-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* fs: don't open code lru_to_page()Nikolay Borisov2019-01-041-1/+1
| | | | | | | | | | | | | | | | | | | Multiple filesystems open code lru_to_page(). Rectify this by moving the macro from mm_inline (which is specific to lru stuff) to the more generic mm.h header and start using the macro where appropriate. No functional changes. Link: http://lkml.kernel.org/r/20181129104810.23361-1-nborisov@suse.com Link: https://lkml.kernel.org/r/20181129075301.29087-1-nborisov@suse.com Signed-off-by: Nikolay Borisov <nborisov@suse.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: David Hildenbrand <david@redhat.com> Reviewed-by: Mike Rapoport <rppt@linux.ibm.com> Acked-by: Pankaj gupta <pagupta@redhat.com> Acked-by: "Yan, Zheng" <zyan@redhat.com> [ceph] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: convert totalram_pages and totalhigh_pages variables to atomicArun KS2018-12-281-1/+1
| | | | | | | | | | | | | | | | | | | | | | | totalram_pages and totalhigh_pages are made static inline function. Main motivation was that managed_page_count_lock handling was complicating things. It was discussed in length here, https://lore.kernel.org/patchwork/patch/995739/#1181785 So it seemes better to remove the lock and convert variables to atomic, with preventing poteintial store-to-read tearing as a bonus. [akpm@linux-foundation.org: coding style fixes] Link: http://lkml.kernel.org/r/1542090790-21750-4-git-send-email-arunks@codeaurora.org Signed-off-by: Arun KS <arunks@codeaurora.org> Suggested-by: Michal Hocko <mhocko@suse.com> Suggested-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: David Hildenbrand <david@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: Replace spin_is_locked() with lockdepLance Roy2018-11-121-2/+1
| | | | | | | | | | | | | | | | | | | lockdep_assert_held() is better suited to checking locking requirements, since it only checks if the current thread holds the lock regardless of whether someone else does. This is also a step towards possibly removing spin_is_locked(). Signed-off-by: Lance Roy <ldr709@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Yang Shi <yang.shi@linux.alibaba.com> Cc: Matthew Wilcox <mawilcox@microsoft.com> Cc: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Jan Kara <jack@suse.cz> Cc: Shakeel Butt <shakeelb@google.com> Cc: <linux-mm@kvack.org> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
* Merge branch 'xarray' of git://git.infradead.org/users/willy/linux-daxLinus Torvalds2018-10-281-3/+3
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull XArray conversion from Matthew Wilcox: "The XArray provides an improved interface to the radix tree data structure, providing locking as part of the API, specifying GFP flags at allocation time, eliminating preloading, less re-walking the tree, more efficient iterations and not exposing RCU-protected pointers to its users. This patch set 1. Introduces the XArray implementation 2. Converts the pagecache to use it 3. Converts memremap to use it The page cache is the most complex and important user of the radix tree, so converting it was most important. Converting the memremap code removes the only other user of the multiorder code, which allows us to remove the radix tree code that supported it. I have 40+ followup patches to convert many other users of the radix tree over to the XArray, but I'd like to get this part in first. The other conversions haven't been in linux-next and aren't suitable for applying yet, but you can see them in the xarray-conv branch if you're interested" * 'xarray' of git://git.infradead.org/users/willy/linux-dax: (90 commits) radix tree: Remove multiorder support radix tree test: Convert multiorder tests to XArray radix tree tests: Convert item_delete_rcu to XArray radix tree tests: Convert item_kill_tree to XArray radix tree tests: Move item_insert_order radix tree test suite: Remove multiorder benchmarking radix tree test suite: Remove __item_insert memremap: Convert to XArray xarray: Add range store functionality xarray: Move multiorder_check to in-kernel tests xarray: Move multiorder_shrink to kernel tests xarray: Move multiorder account test in-kernel radix tree test suite: Convert iteration test to XArray radix tree test suite: Convert tag_tagged_items to XArray radix tree: Remove radix_tree_clear_tags radix tree: Remove radix_tree_maybe_preload_order radix tree: Remove split/join code radix tree: Remove radix_tree_update_node_t page cache: Finish XArray conversion dax: Convert page fault handlers to XArray ...
| * pagevec: Use xa_mark_tMatthew Wilcox2018-10-211-2/+2
| | | | | | | | | | | | Removes sparse warnings. Signed-off-by: Matthew Wilcox <willy@infradead.org>
| * xarray: Replace exceptional entriesMatthew Wilcox2018-09-301-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | Introduce xarray value entries and tagged pointers to replace radix tree exceptional entries. This is a slight change in encoding to allow the use of an extra bit (we can now store BITS_PER_LONG - 1 bits in a value entry). It is also a change in emphasis; exceptional entries are intimidating and different. As the comment explains, you can choose to store values or pointers in the xarray and they are both first-class citizens. Signed-off-by: Matthew Wilcox <willy@infradead.org> Reviewed-by: Josef Bacik <jbacik@fb.com>
* | mm/swap.c: remove duplicated includeYueHaibing2018-10-271-1/+0
|/ | | | | | | | | | Remove duplicated include linux/memremap.h Link: http://lkml.kernel.org/r/20180917131308.16420-1-yuehaibing@huawei.com Signed-off-by: YueHaibing <yuehaibing@huawei.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: introduce MEMORY_DEVICE_FS_DAX and CONFIG_DEV_PAGEMAP_OPSDan Williams2018-05-221-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In preparation for fixing dax-dma-vs-unmap issues, filesystems need to be able to rely on the fact that they will get wakeups on dev_pagemap page-idle events. Introduce MEMORY_DEVICE_FS_DAX and generic_dax_page_free() as common indicator / infrastructure for dax filesytems to require. With this change there are no users of the MEMORY_DEVICE_HOST designation, so remove it. The HMM sub-system extended dev_pagemap to arrange a callback when a dev_pagemap managed page is freed. Since a dev_pagemap page is free / idle when its reference count is 1 it requires an additional branch to check the page-type at put_page() time. Given put_page() is a hot-path we do not want to incur that check if HMM is not in use, so a static branch is used to avoid that overhead when not necessary. Now, the FS_DAX implementation wants to reuse this mechanism for receiving dev_pagemap ->page_free() callbacks. Rework the HMM-specific static-key into a generic mechanism that either HMM or FS_DAX code paths can enable. For ARCH=um builds, and any other arch that lacks ZONE_DEVICE support, care must be taken to compile out the DEV_PAGEMAP_OPS infrastructure. However, we still need to support FS_DAX in the FS_DAX_LIMITED case implemented by the s390/dcssblk driver. Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Michal Hocko <mhocko@suse.com> Reported-by: kbuild test robot <lkp@intel.com> Reported-by: Thomas Meyer <thomas@m3y3r.de> Reported-by: Dave Jiang <dave.jiang@intel.com> Cc: "Jérôme Glisse" <jglisse@redhat.com> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Dan Williams <dan.j.williams@intel.com>