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* mm: fix cache mode tracking in vm_insert_mixed()Dan Williams2016-10-081-2/+6
| | | | | | | | | | | | | | | | vm_insert_mixed() unlike vm_insert_pfn_prot() and vmf_insert_pfn_pmd(), fails to check the pgprot_t it uses for the mapping against the one recorded in the memtype tracking tree. Add the missing call to track_pfn_insert() to preclude cases where incompatible aliased mappings are established for a given physical address range. Link: http://lkml.kernel.org/r/147328717909.35069.14256589123570653697.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Dan Williams <dan.j.williams@intel.com> Cc: David Airlie <airlied@linux.ie> Cc: Matthew Wilcox <mawilcox@microsoft.com> Cc: Ross Zwisler <ross.zwisler@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: make sure that kthreads will not refault oom reaped memoryMichal Hocko2016-10-081-0/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There are only few use_mm() users in the kernel right now. Most of them write to the target memory but vhost driver relies on copy_from_user/get_user from a kernel thread context. This makes it impossible to reap the memory of an oom victim which shares the mm with the vhost kernel thread because it could see a zero page unexpectedly and theoretically make an incorrect decision visible outside of the killed task context. To quote Michael S. Tsirkin: : Getting an error from __get_user and friends is handled gracefully. : Getting zero instead of a real value will cause userspace : memory corruption. The vhost kernel thread is bound to an open fd of the vhost device which is not tight to the mm owner life cycle in general. The device fd can be inherited or passed over to another process which means that we really have to be careful about unexpected memory corruption because unlike for normal oom victims the result will be visible outside of the oom victim context. Make sure that no kthread context (users of use_mm) can ever see corrupted data because of the oom reaper and hook into the page fault path by checking MMF_UNSTABLE mm flag. __oom_reap_task_mm will set the flag before it starts unmapping the address space while the flag is checked after the page fault has been handled. If the flag is set then SIGBUS is triggered so any g-u-p user will get a error code. Regular tasks do not need this protection because all which share the mm are killed when the mm is reaped and so the corruption will not outlive them. This patch shouldn't have any visible effect at this moment because the OOM killer doesn't invoke oom reaper for tasks with mm shared with kthreads yet. Link: http://lkml.kernel.org/r/1472119394-11342-9-git-send-email-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: "Michael S. Tsirkin" <mst@redhat.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Oleg Nesterov <oleg@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Vladimir Davydov <vdavydov@parallels.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Merge branch 'linus' into sched/core, to pick up fixesIngo Molnar2016-09-301-5/+7
|\ | | | | | | Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * mm: check VMA flags to avoid invalid PROT_NONE NUMA balancingLorenzo Stoakes2016-09-261-5/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The NUMA balancing logic uses an arch-specific PROT_NONE page table flag defined by pte_protnone() or pmd_protnone() to mark PTEs or huge page PMDs respectively as requiring balancing upon a subsequent page fault. User-defined PROT_NONE memory regions which also have this flag set will not normally invoke the NUMA balancing code as do_page_fault() will send a segfault to the process before handle_mm_fault() is even called. However if access_remote_vm() is invoked to access a PROT_NONE region of memory, handle_mm_fault() is called via faultin_page() and __get_user_pages() without any access checks being performed, meaning the NUMA balancing logic is incorrectly invoked on a non-NUMA memory region. A simple means of triggering this problem is to access PROT_NONE mmap'd memory using /proc/self/mem which reliably results in the NUMA handling functions being invoked when CONFIG_NUMA_BALANCING is set. This issue was reported in bugzilla (issue 99101) which includes some simple repro code. There are BUG_ON() checks in do_numa_page() and do_huge_pmd_numa_page() added at commit c0e7cad to avoid accidentally provoking strange behaviour by attempting to apply NUMA balancing to pages that are in fact PROT_NONE. The BUG_ON()'s are consistently triggered by the repro. This patch moves the PROT_NONE check into mm/memory.c rather than invoking BUG_ON() as faulting in these pages via faultin_page() is a valid reason for reaching the NUMA check with the PROT_NONE page table flag set and is therefore not always a bug. Link: https://bugzilla.kernel.org/show_bug.cgi?id=99101 Reported-by: Trevor Saunders <tbsaunde@tbsaunde.org> Signed-off-by: Lorenzo Stoakes <lstoakes@gmail.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | sched/numa, mm: Revert to checking pmd/pte_write instead of VMA flagsRik van Riel2016-09-131-1/+1
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit: 4d9424669946 ("mm: convert p[te|md]_mknonnuma and remaining page table manipulations") changed NUMA balancing from _PAGE_NUMA to using PROT_NONE, and was quickly found to introduce a regression with NUMA grouping. It was followed up by these commits: 53da3bc2ba9e ("mm: fix up numa read-only thread grouping logic") bea66fbd11af ("mm: numa: group related processes based on VMA flags instead of page table flags") b191f9b106ea ("mm: numa: preserve PTE write permissions across a NUMA hinting fault") The first of those two commits try alternate approaches to NUMA grouping, which apparently do not work as well as looking at the PTE write permissions. The latter patch preserves the PTE write permissions across a NUMA protection fault. However, it forgets to revert the condition for whether or not to group tasks together back to what it was before v3.19, even though the information is now preserved in the page tables once again. This patch brings the NUMA grouping heuristic back to what it was before commit 4d9424669946, which the changelogs of subsequent commits suggest worked best. We have all the information again. We should probably use it. Signed-off-by: Rik van Riel <riel@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: aarcange@redhat.com Cc: linux-mm@kvack.org Cc: mgorman@suse.de Link: http://lkml.kernel.org/r/20160908213053.07c992a9@annuminas.surriel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* mm: move swap-in anonymous page into active listMinchan Kim2016-08-021-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Every swap-in anonymous page starts from inactive lru list's head. It should be activated unconditionally when VM decide to reclaim because page table entry for the page always usually has marked accessed bit. Thus, their window size for getting a new referece is 2 * NR_inactive + NR_active while others is NR_inactive + NR_active. It's not fair that it has more chance to be referenced compared to other newly allocated page which starts from active lru list's head. Johannes: : The page can still have a valid copy on the swap device, so prefering to : reclaim that page over a fresh one could make sense. But as you point : out, having it start inactive instead of active actually ends up giving it : *more* LRU time, and that seems to be without justification. Rik: : The reason newly read in swap cache pages start on the inactive list is : that we do some amount of read-around, and do not know which pages will : get used. : : However, immediately activating the ones that DO get used, like your patch : does, is the right thing to do. Link: http://lkml.kernel.org/r/1469762740-17860-1-git-send-email-minchan@kernel.org Signed-off-by: Minchan Kim <minchan@kernel.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Rik van Riel <riel@redhat.com> Cc: Nadav Amit <nadav.amit@gmail.com> Cc: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: fail prefaulting if page table allocation failsVegard Nossum2016-08-021-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | I ran into this: BUG: sleeping function called from invalid context at mm/page_alloc.c:3784 in_atomic(): 0, irqs_disabled(): 0, pid: 1434, name: trinity-c1 2 locks held by trinity-c1/1434: #0: (&mm->mmap_sem){......}, at: [<ffffffff810ce31e>] __do_page_fault+0x1ce/0x8f0 #1: (rcu_read_lock){......}, at: [<ffffffff81378f86>] filemap_map_pages+0xd6/0xdd0 CPU: 0 PID: 1434 Comm: trinity-c1 Not tainted 4.7.0+ #58 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014 Call Trace: dump_stack+0x65/0x84 panic+0x185/0x2dd ___might_sleep+0x51c/0x600 __might_sleep+0x90/0x1a0 __alloc_pages_nodemask+0x5b1/0x2160 alloc_pages_current+0xcc/0x370 pte_alloc_one+0x12/0x90 __pte_alloc+0x1d/0x200 alloc_set_pte+0xe3e/0x14a0 filemap_map_pages+0x42b/0xdd0 handle_mm_fault+0x17d5/0x28b0 __do_page_fault+0x310/0x8f0 trace_do_page_fault+0x18d/0x310 do_async_page_fault+0x27/0xa0 async_page_fault+0x28/0x30 The important bits from the above is that filemap_map_pages() is calling into the page allocator while holding rcu_read_lock (sleeping is not allowed inside RCU read-side critical sections). According to Kirill Shutemov, the prefaulting code in do_fault_around() is supposed to take care of this, but missing error handling means that the allocation failure can go unnoticed. We don't need to return VM_FAULT_OOM (or any other error) here, since we can just let the normal fault path try again. Fixes: 7267ec008b5c ("mm: postpone page table allocation until we have page to map") Link: http://lkml.kernel.org/r/1469708107-11868-1-git-send-email-vegard.nossum@oracle.com Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: "Hillf Danton" <hillf.zj@alibaba-inc.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* thp: introduce CONFIG_TRANSPARENT_HUGE_PAGECACHEKirill A. Shutemov2016-07-271-2/+3
| | | | | | | | | | | | | | | | | | | | For file mappings, we don't deposit page tables on THP allocation because it's not strictly required to implement split_huge_pmd(): we can just clear pmd and let following page faults to reconstruct the page table. But Power makes use of deposited page table to address MMU quirk. Let's hide THP page cache, including huge tmpfs, under separate config option, so it can be forbidden on Power. We can revert the patch later once solution for Power found. Link: http://lkml.kernel.org/r/1466021202-61880-36-git-send-email-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* shmem: add huge pages supportKirill A. Shutemov2016-07-271-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Here's basic implementation of huge pages support for shmem/tmpfs. It's all pretty streight-forward: - shmem_getpage() allcoates huge page if it can and try to inserd into radix tree with shmem_add_to_page_cache(); - shmem_add_to_page_cache() puts the page onto radix-tree if there's space for it; - shmem_undo_range() removes huge pages, if it fully within range. Partial truncate of huge pages zero out this part of THP. This have visible effect on fallocate(FALLOC_FL_PUNCH_HOLE) behaviour. As we don't really create hole in this case, lseek(SEEK_HOLE) may have inconsistent results depending what pages happened to be allocated. - no need to change shmem_fault: core-mm will map an compound page as huge if VMA is suitable; Link: http://lkml.kernel.org/r/1466021202-61880-30-git-send-email-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* thp: handle file COW faultsKirill A. Shutemov2016-07-271-0/+5
| | | | | | | | | | | | | | | | File COW for THP is handled on pte level: just split the pmd. It's not clear how benefitial would be allocation of huge pages on COW faults. And it would require some code to make them work. I think at some point we can consider teaching khugepaged to collapse pages in COW mappings, but allocating huge on fault is probably overkill. Link: http://lkml.kernel.org/r/1466021202-61880-16-git-send-email-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* thp, vmstats: add counters for huge file pagesKirill A. Shutemov2016-07-271-0/+1
| | | | | | | | | | | | THP_FILE_ALLOC: how many times huge page was allocated and put page cache. THP_FILE_MAPPED: how many times file huge page was mapped. Link: http://lkml.kernel.org/r/1466021202-61880-13-git-send-email-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: introduce do_set_pmd()Kirill A. Shutemov2016-07-271-1/+71
| | | | | | | | | | | | | | With postponed page table allocation we have chance to setup huge pages. do_set_pte() calls do_set_pmd() if following criteria met: - page is compound; - pmd entry in pmd_none(); - vma has suitable size and alignment; Link: http://lkml.kernel.org/r/1466021202-61880-12-git-send-email-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* rmap: support file thpKirill A. Shutemov2016-07-271-2/+2
| | | | | | | | | | | | | | | Naive approach: on mapping/unmapping the page as compound we update ->_mapcount on each 4k page. That's not efficient, but it's not obvious how we can optimize this. We can look into optimization later. PG_double_map optimization doesn't work for file pages since lifecycle of file pages is different comparing to anon pages: file page can be mapped again at any time. Link: http://lkml.kernel.org/r/1466021202-61880-11-git-send-email-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: postpone page table allocation until we have page to mapKirill A. Shutemov2016-07-271-120/+178
| | | | | | | | | | | | | | | | | | | | | | | The idea (and most of code) is borrowed again: from Hugh's patchset on huge tmpfs[1]. Instead of allocation pte page table upfront, we postpone this until we have page to map in hands. This approach opens possibility to map the page as huge if filesystem supports this. Comparing to Hugh's patch I've pushed page table allocation a bit further: into do_set_pte(). This way we can postpone allocation even in faultaround case without moving do_fault_around() after __do_fault(). do_set_pte() got renamed to alloc_set_pte() as it can allocate page table if required. [1] http://lkml.kernel.org/r/alpine.LSU.2.11.1502202015090.14414@eggly.anvils Link: http://lkml.kernel.org/r/1466021202-61880-10-git-send-email-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: introduce fault_envKirill A. Shutemov2016-07-271-304/+278
| | | | | | | | | | | | | | | | | | | | | | The idea borrowed from Peter's patch from patchset on speculative page faults[1]: Instead of passing around the endless list of function arguments, replace the lot with a single structure so we can change context without endless function signature changes. The changes are mostly mechanical with exception of faultaround code: filemap_map_pages() got reworked a bit. This patch is preparation for the next one. [1] http://lkml.kernel.org/r/20141020222841.302891540@infradead.org Link: http://lkml.kernel.org/r/1466021202-61880-9-git-send-email-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: do not pass mm_struct into handle_mm_faultKirill A. Shutemov2016-07-271-6/+7
| | | | | | | | | We always have vma->vm_mm around. Link: http://lkml.kernel.org/r/1466021202-61880-8-git-send-email-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: make swapin readahead to improve thp collapse rateEbru Akagunduz2016-07-271-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch makes swapin readahead to improve thp collapse rate. When khugepaged scanned pages, there can be a few of the pages in swap area. With the patch THP can collapse 4kB pages into a THP when there are up to max_ptes_swap swap ptes in a 2MB range. The patch was tested with a test program that allocates 400B of memory, writes to it, and then sleeps. I force the system to swap out all. Afterwards, the test program touches the area by writing, it skips a page in each 20 pages of the area. Without the patch, system did not swap in readahead. THP rate was %65 of the program of the memory, it did not change over time. With this patch, after 10 minutes of waiting khugepaged had collapsed %99 of the program's memory. [kirill.shutemov@linux.intel.com: trivial cleanup of exit path of the function] [kirill.shutemov@linux.intel.com: __collapse_huge_page_swapin(): drop unused 'pte' parameter] [kirill.shutemov@linux.intel.com: do not hold anon_vma lock during swap in] Signed-off-by: Ebru Akagunduz <ebru.akagunduz@gmail.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Xie XiuQi <xiexiuqi@huawei.com> Cc: Cyrill Gorcunov <gorcunov@openvz.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: David Rientjes <rientjes@google.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/mmu_gather: track page size with mmu gather and force flush if page size ↵Aneesh Kumar K.V2016-07-271-1/+9
| | | | | | | | | | | | | | | | | | | | | | | change This allows an arch which needs to do special handing with respect to different page size when flushing tlb to implement the same in mmu gather. Link: http://lkml.kernel.org/r/1465049193-22197-3-git-send-email-aneesh.kumar@linux.vnet.ibm.com Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Hugh Dickins <hughd@google.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@suse.de> Cc: David Rientjes <rientjes@google.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Minchan Kim <minchan.kim@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: change the interface for __tlb_remove_page()Aneesh Kumar K.V2016-07-271-6/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This updates the generic and arch specific implementation to return true if we need to do a tlb flush. That means if a __tlb_remove_page indicate a flush is needed, the page we try to remove need to be tracked and added again after the flush. We need to track it because we have already update the pte to none and we can't just loop back. This change is done to enable us to do a tlb_flush when we try to flush a range that consists of different page sizes. For architectures like ppc64, we can do a range based tlb flush and we need to track page size for that. When we try to remove a huge page, we will force a tlb flush and starts a new mmu gather. [aneesh.kumar@linux.vnet.ibm.com: mm-change-the-interface-for-__tlb_remove_page-v3] Link: http://lkml.kernel.org/r/1465049193-22197-2-git-send-email-aneesh.kumar@linux.vnet.ibm.com Link: http://lkml.kernel.org/r/1464860389-29019-2-git-send-email-aneesh.kumar@linux.vnet.ibm.com Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Hugh Dickins <hughd@google.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@suse.de> Cc: David Rientjes <rientjes@google.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Minchan Kim <minchan.kim@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: thp: refix false positive BUG in page_move_anon_rmap()Hugh Dickins2016-07-151-2/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The VM_BUG_ON_PAGE in page_move_anon_rmap() is more trouble than it's worth: the syzkaller fuzzer hit it again. It's still wrong for some THP cases, because linear_page_index() was never intended to apply to addresses before the start of a vma. That's easily fixed with a signed long cast inside linear_page_index(); and Dmitry has tested such a patch, to verify the false positive. But why extend linear_page_index() just for this case? when the avoidance in page_move_anon_rmap() has already grown ugly, and there's no reason for the check at all (nothing else there is using address or index). Remove address arg from page_move_anon_rmap(), remove VM_BUG_ON_PAGE, remove CONFIG_DEBUG_VM PageTransHuge adjustment. And one more thing: should the compound_head(page) be done inside or outside page_move_anon_rmap()? It's usually pushed down to the lowest level nowadays (and mm/memory.c shows no other explicit use of it), so I think it's better done in page_move_anon_rmap() than by caller. Fixes: 0798d3c022dc ("mm: thp: avoid false positive VM_BUG_ON_PAGE in page_move_anon_rmap()") Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1607120444540.12528@eggly.anvils Signed-off-by: Hugh Dickins <hughd@google.com> Reported-by: Dmitry Vyukov <dvyukov@google.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Mika Westerberg <mika.westerberg@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Rik van Riel <riel@redhat.com> Cc: <stable@vger.kernel.org> [4.5+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Revert "mm: disable fault around on emulated access bit architecture"Kirill A. Shutemov2016-06-251-8/+0
| | | | | | | | | | | | | | | | | | | | | This reverts commit d0834a6c2c5b0c76cfb806bd7dba6556d8b4edbb. After revert of 5c0a85fad949 ("mm: make faultaround produce old ptes") faultaround doesn't have dependencies on hardware accessed bit, so let's revert this one too. Link: http://lkml.kernel.org/r/1465893750-44080-3-git-send-email-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reported-by: "Huang, Ying" <ying.huang@intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@suse.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Vinayak Menon <vinmenon@codeaurora.org> Cc: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Revert "mm: make faultaround produce old ptes"Kirill A. Shutemov2016-06-251-18/+5
| | | | | | | | | | | | | | | | | | | | | | This reverts commit 5c0a85fad949212b3e059692deecdeed74ae7ec7. The commit causes ~6% regression in unixbench. Let's revert it for now and consider other solution for reclaim problem later. Link: http://lkml.kernel.org/r/1465893750-44080-2-git-send-email-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reported-by: "Huang, Ying" <ying.huang@intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@suse.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Vinayak Menon <vinmenon@codeaurora.org> Cc: Dave Hansen <dave.hansen@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Merge tag 'dax-locking-for-4.7' of ↵Linus Torvalds2016-05-271-22/+18
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm Pull DAX locking updates from Ross Zwisler: "Filesystem DAX locking for 4.7 - We use a bit in an exceptional radix tree entry as a lock bit and use it similarly to how page lock is used for normal faults. This fixes races between hole instantiation and read faults of the same index. - Filesystem DAX PMD faults are disabled, and will be re-enabled when PMD locking is implemented" * tag 'dax-locking-for-4.7' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm: dax: Remove i_mmap_lock protection dax: Use radix tree entry lock to protect cow faults dax: New fault locking dax: Allow DAX code to replace exceptional entries dax: Define DAX lock bit for radix tree exceptional entry dax: Make huge page handling depend of CONFIG_BROKEN dax: Fix condition for filling of PMD holes
| * dax: Remove i_mmap_lock protectionJan Kara2016-05-191-2/+0
| | | | | | | | | | | | | | | | | | | | | | Currently faults are protected against truncate by filesystem specific i_mmap_sem and page lock in case of hole page. Cow faults are protected DAX radix tree entry locking. So there's no need for i_mmap_lock in DAX code. Remove it. Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
| * dax: Use radix tree entry lock to protect cow faultsJan Kara2016-05-191-20/+18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When doing cow faults, we cannot directly fill in PTE as we do for other faults as we rely on generic code to do proper accounting of the cowed page. We also have no page to lock to protect against races with truncate as other faults have and we need the protection to extend until the moment generic code inserts cowed page into PTE thus at that point we have no protection of fs-specific i_mmap_sem. So far we relied on using i_mmap_lock for the protection however that is completely special to cow faults. To make fault locking more uniform use DAX entry lock instead. Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
* | mm: disable fault around on emulated access bit architectureMinchan Kim2016-05-211-0/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | fault_around aims to reduce minor faults of file-backed pages via speculative ahead pte mapping and relying on readahead logic. However, on non-HW access bit architecture the benefit is highly limited because they should emulate the young bit with minor faults for reclaim's page aging algorithm. IOW, we cannot reduce minor faults on those architectures. I did quick a test on my ARM machine. 512M file mmap sequential every word read on eSATA drive 4 times. stddev is stable. = fault_around 4096 = elapsed time(usec): 6747645 = fault_around 65536 = elapsed time(usec): 6709263 0.5% gain. Even when I tested it with eMMC there is no gain because I guess with slow storage the major fault is the dominant factor. Also, fault_around has the side effect of shrinking slab more aggressively and causes higher vmpressure, so if such speculation fails, it can evict slab more which can result in page I/O (e.g., inode cache). In the end, it would make void any benefit of fault_around. So let's make the default "disabled" on those architectures. Link: http://lkml.kernel.org/r/20160518014229.GB21538@bbox Signed-off-by: Minchan Kim <minchan@kernel.org> Cc: Kirill A. Shutemov <kirill@shutemov.name> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | mm: make faultaround produce old ptesKirill A. Shutemov2016-05-211-5/+18
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, faultaround code produces young pte. This can screw up vmscan behaviour[1], as it makes vmscan think that these pages are hot and not push them out on first round. During sparse file access faultaround gets more pages mapped and all of them are young. Under memory pressure, this makes vmscan swap out anon pages instead, or to drop other page cache pages which otherwise stay resident. Modify faultaround to produce old ptes, so they can easily be reclaimed under memory pressure. This can to some extend defeat the purpose of faultaround on machines without hardware accessed bit as it will not help us with reducing the number of minor page faults. We may want to disable faultaround on such machines altogether, but that's subject for separate patchset. Minchan: "I tested 512M mmap sequential word read test on non-HW access bit system (i.e., ARM) and confirmed it doesn't increase minor fault any more. old: 4096 fault_around minor fault: 131291 elapsed time: 6747645 usec new: 65536 fault_around minor fault: 131291 elapsed time: 6709263 usec 0.56% benefit" [1] https://lkml.kernel.org/r/1460992636-711-1-git-send-email-vinmenon@codeaurora.org Link: http://lkml.kernel.org/r/1463488366-47723-1-git-send-email-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Minchan Kim <minchan@kernel.org> Tested-by: Minchan Kim <minchan@kernel.org> Acked-by: Rik van Riel <riel@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Michal Hocko <mhocko@kernel.org> Cc: Vinayak Menon <vinmenon@codeaurora.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | mm: fix incorrect pfn passed to untrack_pfn() in remap_pfn_range()Yongji Xie2016-05-211-2/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We use generic hooks in remap_pfn_range() to help archs to track pfnmap regions. The code is something like: int remap_pfn_range() { ... track_pfn_remap(vma, &prot, pfn, addr, PAGE_ALIGN(size)); ... pfn -= addr >> PAGE_SHIFT; ... untrack_pfn(vma, pfn, PAGE_ALIGN(size)); ... } Here we can easily find the pfn is changed but not recovered before untrack_pfn() is called. That's incorrect. There are no known runtime effects - this is from inspection. Signed-off-by: Yongji Xie <xyjxie@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Jerome Marchand <jmarchan@redhat.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Matthew Wilcox <matthew.r.wilcox@intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: David Hildenbrand <dahi@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | mm: thp: calculate the mapcount correctly for THP pages during WP faultsAndrea Arcangeli2016-05-131-8/+14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This will provide fully accuracy to the mapcount calculation in the write protect faults, so page pinning will not get broken by false positive copy-on-writes. total_mapcount() isn't the right calculation needed in reuse_swap_page(), so this introduces a page_trans_huge_mapcount() that is effectively the full accurate return value for page_mapcount() if dealing with Transparent Hugepages, however we only use the page_trans_huge_mapcount() during COW faults where it strictly needed, due to its higher runtime cost. This also provide at practical zero cost the total_mapcount information which is needed to know if we can still relocate the page anon_vma to the local vma. If page_trans_huge_mapcount() returns 1 we can reuse the page no matter if it's a pte or a pmd_trans_huge triggering the fault, but we can only relocate the page anon_vma to the local vma->anon_vma if we're sure it's only this "vma" mapping the whole THP physical range. Kirill A. Shutemov discovered the problem with moving the page anon_vma to the local vma->anon_vma in a previous version of this patch and another problem in the way page_move_anon_rmap() was called. Andrew Morton discovered that CONFIG_SWAP=n wouldn't build in a previous version, because reuse_swap_page must be a macro to call page_trans_huge_mapcount from swap.h, so this uses a macro again instead of an inline function. With this change at least it's a less dangerous usage than it was before, because "page" is used only once now, while with the previous code reuse_swap_page(page++) would have called page_mapcount on page+1 and it would have increased page twice instead of just once. Dean Luick noticed an uninitialized variable that could result in a rmap inefficiency for the non-THP case in a previous version. Mike Marciniszyn said: : Our RDMA tests are seeing an issue with memory locking that bisects to : commit 61f5d698cc97 ("mm: re-enable THP") : : The test program registers two rather large MRs (512M) and RDMA : writes data to a passive peer using the first and RDMA reads it back : into the second MR and compares that data. The sizes are chosen randomly : between 0 and 1024 bytes. : : The test will get through a few (<= 4 iterations) and then gets a : compare error. : : Tracing indicates the kernel logical addresses associated with the individual : pages at registration ARE correct , the data in the "RDMA read response only" : packets ARE correct. : : The "corruption" occurs when the packet crosse two pages that are not physically : contiguous. The second page reads back as zero in the program. : : It looks like the user VA at the point of the compare error no longer points to : the same physical address as was registered. : : This patch totally resolves the issue! Link: http://lkml.kernel.org/r/1462547040-1737-2-git-send-email-aarcange@redhat.com Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Reviewed-by: "Kirill A. Shutemov" <kirill@shutemov.name> Reviewed-by: Dean Luick <dean.luick@intel.com> Tested-by: Alex Williamson <alex.williamson@redhat.com> Tested-by: Mike Marciniszyn <mike.marciniszyn@intel.com> Tested-by: Josh Collier <josh.d.collier@intel.com> Cc: Marc Haber <mh+linux-kernel@zugschlus.de> Cc: <stable@vger.kernel.org> [4.5] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | huge pagecache: mmap_sem is unlocked when truncation splits pmdHugh Dickins2016-05-061-9/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | zap_pmd_range()'s CONFIG_DEBUG_VM !rwsem_is_locked(&mmap_sem) BUG() will be invalid with huge pagecache, in whatever way it is implemented: truncation of a hugely-mapped file to an unhugely-aligned size would easily hit it. (Although anon THP could in principle apply khugepaged to private file mappings, which are not excluded by the MADV_HUGEPAGE restrictions, in practice there's a vm_ops check which excludes them, so it never hits this BUG() - there's no interface to "truncate" an anonymous mapping.) We could complicate the test, to check i_mmap_rwsem also when there's a vm_file; but my inclination was to make zap_pmd_range() more readable by simply deleting this check. A search has shown no report of the issue in the years since commit e0897d75f0b2 ("mm, thp: print useful information when mmap_sem is unlocked in zap_pmd_range") expanded it from VM_BUG_ON() - though I cannot point to what commit I would say then fixed the issue. But there are a couple of other patches now floating around, neither yet in the tree: let's agree to retain the check as a VM_BUG_ON_VMA(), as Matthew Wilcox has done; but subject to a vma_is_anonymous() check, as Kirill Shutemov has done. And let's get this in, without waiting for any particular huge pagecache implementation to reach the tree. Matthew said "We can reproduce this BUG() in the current Linus tree with DAX PMDs". Signed-off-by: Hugh Dickins <hughd@google.com> Tested-by: Matthew Wilcox <willy@linux.intel.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Andres Lagar-Cavilla <andreslc@google.com> Cc: Yang Shi <yang.shi@linaro.org> Cc: Ning Qu <quning@gmail.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Andres Lagar-Cavilla <andreslc@google.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | numa: fix /proc/<pid>/numa_maps for THPGerald Schaefer2016-04-291-0/+40
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In gather_pte_stats() a THP pmd is cast into a pte, which is wrong because the layouts may differ depending on the architecture. On s390 this will lead to inaccurate numa_maps accounting in /proc because of misguided pte_present() and pte_dirty() checks on the fake pte. On other architectures pte_present() and pte_dirty() may work by chance, but there may be an issue with direct-access (dax) mappings w/o underlying struct pages when HAVE_PTE_SPECIAL is set and THP is available. In vm_normal_page() the fake pte will be checked with pte_special() and because there is no "special" bit in a pmd, this will always return false and the VM_PFNMAP | VM_MIXEDMAP checking will be skipped. On dax mappings w/o struct pages, an invalid struct page pointer would then be returned that can crash the kernel. This patch fixes the numa_maps THP handling by introducing new "_pmd" variants of the can_gather_numa_stats() and vm_normal_page() functions. Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Jerome Marchand <jmarchan@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Michael Holzheu <holzheu@linux.vnet.ibm.com> Cc: <stable@vger.kernel.org> [4.3+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, fs: remove remaining PAGE_CACHE_* and page_cache_{get,release} usageKirill A. Shutemov2016-04-041-1/+0
| | | | | | | | | Mostly direct substitution with occasional adjustment or removing outdated comments. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macrosKirill A. Shutemov2016-04-041-27/+27
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} macros were introduced *long* time ago with promise that one day it will be possible to implement page cache with bigger chunks than PAGE_SIZE. This promise never materialized. And unlikely will. We have many places where PAGE_CACHE_SIZE assumed to be equal to PAGE_SIZE. And it's constant source of confusion on whether PAGE_CACHE_* or PAGE_* constant should be used in a particular case, especially on the border between fs and mm. Global switching to PAGE_CACHE_SIZE != PAGE_SIZE would cause to much breakage to be doable. Let's stop pretending that pages in page cache are special. They are not. The changes are pretty straight-forward: - <foo> << (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>; - <foo> >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) -> <foo>; - PAGE_CACHE_{SIZE,SHIFT,MASK,ALIGN} -> PAGE_{SIZE,SHIFT,MASK,ALIGN}; - page_cache_get() -> get_page(); - page_cache_release() -> put_page(); This patch contains automated changes generated with coccinelle using script below. For some reason, coccinelle doesn't patch header files. I've called spatch for them manually. The only adjustment after coccinelle is revert of changes to PAGE_CAHCE_ALIGN definition: we are going to drop it later. There are few places in the code where coccinelle didn't reach. I'll fix them manually in a separate patch. Comments and documentation also will be addressed with the separate patch. virtual patch @@ expression E; @@ - E << (PAGE_CACHE_SHIFT - PAGE_SHIFT) + E @@ expression E; @@ - E >> (PAGE_CACHE_SHIFT - PAGE_SHIFT) + E @@ @@ - PAGE_CACHE_SHIFT + PAGE_SHIFT @@ @@ - PAGE_CACHE_SIZE + PAGE_SIZE @@ @@ - PAGE_CACHE_MASK + PAGE_MASK @@ expression E; @@ - PAGE_CACHE_ALIGN(E) + PAGE_ALIGN(E) @@ expression E; @@ - page_cache_get(E) + get_page(E) @@ expression E; @@ - page_cache_release(E) + put_page(E) Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, oom: introduce oom reaperMichal Hocko2016-03-261-7/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch (of 5): This is based on the idea from Mel Gorman discussed during LSFMM 2015 and independently brought up by Oleg Nesterov. The OOM killer currently allows to kill only a single task in a good hope that the task will terminate in a reasonable time and frees up its memory. Such a task (oom victim) will get an access to memory reserves via mark_oom_victim to allow a forward progress should there be a need for additional memory during exit path. It has been shown (e.g. by Tetsuo Handa) that it is not that hard to construct workloads which break the core assumption mentioned above and the OOM victim might take unbounded amount of time to exit because it might be blocked in the uninterruptible state waiting for an event (e.g. lock) which is blocked by another task looping in the page allocator. This patch reduces the probability of such a lockup by introducing a specialized kernel thread (oom_reaper) which tries to reclaim additional memory by preemptively reaping the anonymous or swapped out memory owned by the oom victim under an assumption that such a memory won't be needed when its owner is killed and kicked from the userspace anyway. There is one notable exception to this, though, if the OOM victim was in the process of coredumping the result would be incomplete. This is considered a reasonable constrain because the overall system health is more important than debugability of a particular application. A kernel thread has been chosen because we need a reliable way of invocation so workqueue context is not appropriate because all the workers might be busy (e.g. allocating memory). Kswapd which sounds like another good fit is not appropriate as well because it might get blocked on locks during reclaim as well. oom_reaper has to take mmap_sem on the target task for reading so the solution is not 100% because the semaphore might be held or blocked for write but the probability is reduced considerably wrt. basically any lock blocking forward progress as described above. In order to prevent from blocking on the lock without any forward progress we are using only a trylock and retry 10 times with a short sleep in between. Users of mmap_sem which need it for write should be carefully reviewed to use _killable waiting as much as possible and reduce allocations requests done with the lock held to absolute minimum to reduce the risk even further. The API between oom killer and oom reaper is quite trivial. wake_oom_reaper updates mm_to_reap with cmpxchg to guarantee only NULL->mm transition and oom_reaper clear this atomically once it is done with the work. This means that only a single mm_struct can be reaped at the time. As the operation is potentially disruptive we are trying to limit it to the ncessary minimum and the reaper blocks any updates while it operates on an mm. mm_struct is pinned by mm_count to allow parallel exit_mmap and a race is detected by atomic_inc_not_zero(mm_users). Signed-off-by: Michal Hocko <mhocko@suse.com> Suggested-by: Oleg Nesterov <oleg@redhat.com> Suggested-by: Mel Gorman <mgorman@suse.de> Acked-by: Mel Gorman <mgorman@suse.de> Acked-by: David Rientjes <rientjes@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Andrea Argangeli <andrea@kernel.org> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Merge branch 'mm-pkeys-for-linus' of ↵Linus Torvalds2016-03-211-1/+7
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull x86 protection key support from Ingo Molnar: "This tree adds support for a new memory protection hardware feature that is available in upcoming Intel CPUs: 'protection keys' (pkeys). There's a background article at LWN.net: https://lwn.net/Articles/643797/ The gist is that protection keys allow the encoding of user-controllable permission masks in the pte. So instead of having a fixed protection mask in the pte (which needs a system call to change and works on a per page basis), the user can map a (handful of) protection mask variants and can change the masks runtime relatively cheaply, without having to change every single page in the affected virtual memory range. This allows the dynamic switching of the protection bits of large amounts of virtual memory, via user-space instructions. It also allows more precise control of MMU permission bits: for example the executable bit is separate from the read bit (see more about that below). This tree adds the MM infrastructure and low level x86 glue needed for that, plus it adds a high level API to make use of protection keys - if a user-space application calls: mmap(..., PROT_EXEC); or mprotect(ptr, sz, PROT_EXEC); (note PROT_EXEC-only, without PROT_READ/WRITE), the kernel will notice this special case, and will set a special protection key on this memory range. It also sets the appropriate bits in the Protection Keys User Rights (PKRU) register so that the memory becomes unreadable and unwritable. So using protection keys the kernel is able to implement 'true' PROT_EXEC on x86 CPUs: without protection keys PROT_EXEC implies PROT_READ as well. Unreadable executable mappings have security advantages: they cannot be read via information leaks to figure out ASLR details, nor can they be scanned for ROP gadgets - and they cannot be used by exploits for data purposes either. We know about no user-space code that relies on pure PROT_EXEC mappings today, but binary loaders could start making use of this new feature to map binaries and libraries in a more secure fashion. There is other pending pkeys work that offers more high level system call APIs to manage protection keys - but those are not part of this pull request. Right now there's a Kconfig that controls this feature (CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS) that is default enabled (like most x86 CPU feature enablement code that has no runtime overhead), but it's not user-configurable at the moment. If there's any serious problem with this then we can make it configurable and/or flip the default" * 'mm-pkeys-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (38 commits) x86/mm/pkeys: Fix mismerge of protection keys CPUID bits mm/pkeys: Fix siginfo ABI breakage caused by new u64 field x86/mm/pkeys: Fix access_error() denial of writes to write-only VMA mm/core, x86/mm/pkeys: Add execute-only protection keys support x86/mm/pkeys: Create an x86 arch_calc_vm_prot_bits() for VMA flags x86/mm/pkeys: Allow kernel to modify user pkey rights register x86/fpu: Allow setting of XSAVE state x86/mm: Factor out LDT init from context init mm/core, x86/mm/pkeys: Add arch_validate_pkey() mm/core, arch, powerpc: Pass a protection key in to calc_vm_flag_bits() x86/mm/pkeys: Actually enable Memory Protection Keys in the CPU x86/mm/pkeys: Add Kconfig prompt to existing config option x86/mm/pkeys: Dump pkey from VMA in /proc/pid/smaps x86/mm/pkeys: Dump PKRU with other kernel registers mm/core, x86/mm/pkeys: Differentiate instruction fetches x86/mm/pkeys: Optimize fault handling in access_error() mm/core: Do not enforce PKEY permissions on remote mm access um, pkeys: Add UML arch_*_access_permitted() methods mm/gup, x86/mm/pkeys: Check VMAs and PTEs for protection keys x86/mm/gup: Simplify get_user_pages() PTE bit handling ...
| * mm/core, x86/mm/pkeys: Differentiate instruction fetchesDave Hansen2016-02-181-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | As discussed earlier, we attempt to enforce protection keys in software. However, the code checks all faults to ensure that they are not violating protection key permissions. It was assumed that all faults are either write faults where we check PKRU[key].WD (write disable) or read faults where we check the AD (access disable) bit. But, there is a third category of faults for protection keys: instruction faults. Instruction faults never run afoul of protection keys because they do not affect instruction fetches. So, plumb the PF_INSTR bit down in to the arch_vma_access_permitted() function where we do the protection key checks. We also add a new FAULT_FLAG_INSTRUCTION. This is because handle_mm_fault() is not passed the architecture-specific error_code where we keep PF_INSTR, so we need to encode the instruction fetch information in to the arch-generic fault flags. Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dave Hansen <dave@sr71.net> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/20160212210224.96928009@viggo.jf.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * mm/core: Do not enforce PKEY permissions on remote mm accessDave Hansen2016-02-181-1/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We try to enforce protection keys in software the same way that we do in hardware. (See long example below). But, we only want to do this when accessing our *own* process's memory. If GDB set PKRU[6].AD=1 (disable access to PKEY 6), then tried to PTRACE_POKE a target process which just happened to have some mprotect_pkey(pkey=6) memory, we do *not* want to deny the debugger access to that memory. PKRU is fundamentally a thread-local structure and we do not want to enforce it on access to _another_ thread's data. This gets especially tricky when we have workqueues or other delayed-work mechanisms that might run in a random process's context. We can check that we only enforce pkeys when operating on our *own* mm, but delayed work gets performed when a random user context is active. We might end up with a situation where a delayed-work gup fails when running randomly under its "own" task but succeeds when running under another process. We want to avoid that. To avoid that, we use the new GUP flag: FOLL_REMOTE and add a fault flag: FAULT_FLAG_REMOTE. They indicate that we are walking an mm which is not guranteed to be the same as current->mm and should not be subject to protection key enforcement. Thanks to Jerome Glisse for pointing out this scenario. Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Cc: Alexey Kardashevskiy <aik@ozlabs.ru> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Boaz Harrosh <boaz@plexistor.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Dave Chinner <dchinner@redhat.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Dominik Dingel <dingel@linux.vnet.ibm.com> Cc: Dominik Vogt <vogt@linux.vnet.ibm.com> Cc: Eric B Munson <emunson@akamai.com> Cc: Geliang Tang <geliangtang@163.com> Cc: Guan Xuetao <gxt@mprc.pku.edu.cn> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Jason Low <jason.low2@hp.com> Cc: Jerome Marchand <jmarchan@redhat.com> Cc: Joerg Roedel <joro@8bytes.org> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Konstantin Khlebnikov <koct9i@gmail.com> Cc: Laurent Dufour <ldufour@linux.vnet.ibm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Matthew Wilcox <willy@linux.intel.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Michal Hocko <mhocko@suse.com> Cc: Mikulas Patocka <mpatocka@redhat.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Shachar Raindel <raindel@mellanox.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Xie XiuQi <xiexiuqi@huawei.com> Cc: iommu@lists.linux-foundation.org Cc: linux-arch@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org Cc: linux-s390@vger.kernel.org Cc: linuxppc-dev@lists.ozlabs.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * mm/gup, x86/mm/pkeys: Check VMAs and PTEs for protection keysDave Hansen2016-02-181-0/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Today, for normal faults and page table walks, we check the VMA and/or PTE to ensure that it is compatible with the action. For instance, if we get a write fault on a non-writeable VMA, we SIGSEGV. We try to do the same thing for protection keys. Basically, we try to make sure that if a user does this: mprotect(ptr, size, PROT_NONE); *ptr = foo; they see the same effects with protection keys when they do this: mprotect(ptr, size, PROT_READ|PROT_WRITE); set_pkey(ptr, size, 4); wrpkru(0xffffff3f); // access disable pkey 4 *ptr = foo; The state to do that checking is in the VMA, but we also sometimes have to do it on the page tables only, like when doing a get_user_pages_fast() where we have no VMA. We add two functions and expose them to generic code: arch_pte_access_permitted(pte_flags, write) arch_vma_access_permitted(vma, write) These are, of course, backed up in x86 arch code with checks against the PTE or VMA's protection key. But, there are also cases where we do not want to respect protection keys. When we ptrace(), for instance, we do not want to apply the tracer's PKRU permissions to the PTEs from the process being traced. Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Cc: Alexey Kardashevskiy <aik@ozlabs.ru> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Andy Lutomirski <luto@kernel.org> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Boaz Harrosh <boaz@plexistor.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Dave Hansen <dave@sr71.net> Cc: David Gibson <david@gibson.dropbear.id.au> Cc: David Hildenbrand <dahi@linux.vnet.ibm.com> Cc: David Vrabel <david.vrabel@citrix.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Dominik Dingel <dingel@linux.vnet.ibm.com> Cc: Dominik Vogt <vogt@linux.vnet.ibm.com> Cc: Guan Xuetao <gxt@mprc.pku.edu.cn> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jason Low <jason.low2@hp.com> Cc: Jerome Marchand <jmarchan@redhat.com> Cc: Juergen Gross <jgross@suse.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Laurent Dufour <ldufour@linux.vnet.ibm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Matthew Wilcox <willy@linux.intel.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Michal Hocko <mhocko@suse.com> Cc: Mikulas Patocka <mpatocka@redhat.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Shachar Raindel <raindel@mellanox.com> Cc: Stephen Smalley <sds@tycho.nsa.gov> Cc: Toshi Kani <toshi.kani@hpe.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: linux-arch@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org Cc: linux-s390@vger.kernel.org Cc: linuxppc-dev@lists.ozlabs.org Link: http://lkml.kernel.org/r/20160212210219.14D5D715@viggo.jf.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * mm/gup: Introduce get_user_pages_remote()Dave Hansen2016-02-161-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | For protection keys, we need to understand whether protections should be enforced in software or not. In general, we enforce protections when working on our own task, but not when on others. We call these "current" and "remote" operations. This patch introduces a new get_user_pages() variant: get_user_pages_remote() Which is a replacement for when get_user_pages() is called on non-current tsk/mm. We also introduce a new gup flag: FOLL_REMOTE which can be used for the "__" gup variants to get this new behavior. The uprobes is_trap_at_addr() location holds mmap_sem and calls get_user_pages(current->mm) on an instruction address. This makes it a pretty unique gup caller. Being an instruction access and also really originating from the kernel (vs. the app), I opted to consider this a 'remote' access where protection keys will not be enforced. Without protection keys, this patch should not change any behavior. Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dave Hansen <dave@sr71.net> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: jack@suse.cz Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/20160212210154.3F0E51EA@viggo.jf.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * Merge branches 'x86/fpu', 'x86/mm' and 'x86/asm' into x86/pkeysIngo Molnar2016-02-161-2/+23
| |\ | | | | | | | | | | | | | | | | | | Provide a stable basis for the pkeys patches, which touches various x86 details. Signed-off-by: Ingo Molnar <mingo@kernel.org>
* | | mm: convert printk(KERN_<LEVEL> to pr_<level>Joe Perches2016-03-171-10/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Most of the mm subsystem uses pr_<level> so make it consistent. Miscellanea: - Realign arguments - Add missing newline to format - kmemleak-test.c has a "kmemleak: " prefix added to the "Kmemleak testing" logging message via pr_fmt Signed-off-by: Joe Perches <joe@perches.com> Acked-by: Tejun Heo <tj@kernel.org> [percpu] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | | mm: cleanup *pte_alloc* interfacesKirill A. Shutemov2016-03-171-5/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There are few things about *pte_alloc*() helpers worth cleaning up: - 'vma' argument is unused, let's drop it; - most __pte_alloc() callers do speculative check for pmd_none(), before taking ptl: let's introduce pte_alloc() macro which does the check. The only direct user of __pte_alloc left is userfaultfd, which has different expectation about atomicity wrt pmd. - pte_alloc_map() and pte_alloc_map_lock() are redefined using pte_alloc(). [sudeep.holla@arm.com: fix build for arm64 hugetlbpage] [sfr@canb.auug.org.au: fix arch/arm/mm/mmu.c some more] Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Dave Hansen <dave.hansen@intel.com> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | | Merge branch 'akpm' (patches from Andrew)Linus Torvalds2016-03-161-3/+4
|\ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Merge first patch-bomb from Andrew Morton: - some misc things - ofs2 updates - about half of MM - checkpatch updates - autofs4 update * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (120 commits) autofs4: fix string.h include in auto_dev-ioctl.h autofs4: use pr_xxx() macros directly for logging autofs4: change log print macros to not insert newline autofs4: make autofs log prints consistent autofs4: fix some white space errors autofs4: fix invalid ioctl return in autofs4_root_ioctl_unlocked() autofs4: fix coding style line length in autofs4_wait() autofs4: fix coding style problem in autofs4_get_set_timeout() autofs4: coding style fixes autofs: show pipe inode in mount options kallsyms: add support for relative offsets in kallsyms address table kallsyms: don't overload absolute symbol type for percpu symbols x86: kallsyms: disable absolute percpu symbols on !SMP checkpatch: fix another left brace warning checkpatch: improve UNSPECIFIED_INT test for bare signed/unsigned uses checkpatch: warn on bare unsigned or signed declarations without int checkpatch: exclude asm volatile from complex macro check mm: memcontrol: drop unnecessary lru locking from mem_cgroup_migrate() mm: migrate: consolidate mem_cgroup_migrate() calls mm/compaction: speed up pageblock_pfn_to_page() when zone is contiguous ...
| * | | mm: use linear_page_index() in do_fault()Matthew Wilcox2016-03-161-2/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | do_fault() assumes that PAGE_SIZE is the same as PAGE_CACHE_SIZE. Use linear_page_index() to calculate pgoff in the correct units. Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| * | | mm/memory.c: make apply_to_page_range() more robustMika Penttilä2016-03-161-1/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Arm and arm64 used to trigger this BUG_ON() - this has now been fixed. But a WARN_ON() here is sufficient to catch future buggy callers. Signed-off-by: Mika Penttilä <mika.penttila@nextfour.com> Reviewed-by: Pekka Enberg <penberg@kernel.org> Acked-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | | | Merge tag 'v4.5-rc7' into x86/asm, to pick up SMAP fixIngo Molnar2016-03-071-2/+12
|\| | | | | | | | | | | | | | | Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * | | mm: thp: fix SMP race condition between THP page fault and MADV_DONTNEEDAndrea Arcangeli2016-02-271-2/+12
| |/ / | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | pmd_trans_unstable()/pmd_none_or_trans_huge_or_clear_bad() were introduced to locklessy (but atomically) detect when a pmd is a regular (stable) pmd or when the pmd is unstable and can infinitely transition from pmd_none() and pmd_trans_huge() from under us, while only holding the mmap_sem for reading (for writing not). While holding the mmap_sem only for reading, MADV_DONTNEED can run from under us and so before we can assume the pmd to be a regular stable pmd we need to compare it against pmd_none() and pmd_trans_huge() in an atomic way, with pmd_trans_unstable(). The old pmd_trans_huge() left a tiny window for a race. Useful applications are unlikely to notice the difference as doing MADV_DONTNEED concurrently with a page fault would lead to undefined behavior. [akpm@linux-foundation.org: tidy up comment grammar/layout] Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Reported-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | / Merge branch 'x86/urgent' into x86/asm, to pick up fixesIngo Molnar2016-02-181-7/+7
|\| | | |/ |/| | | Signed-off-by: Ingo Molnar <mingo@kernel.org>
| * mm: retire GUP WARN_ON_ONCE that outlived its usefulnessHugh Dickins2016-02-031-5/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Trinity is now hitting the WARN_ON_ONCE we added in v3.15 commit cda540ace6a1 ("mm: get_user_pages(write,force) refuse to COW in shared areas"). The warning has served its purpose, nobody was harmed by that change, so just remove the warning to generate less noise from Trinity. Which reminds me of the comment I wrongly left behind with that commit (but was spotted at the time by Kirill), which has since moved into a separate function, and become even more obscure: delete it. Reported-by: Dave Jones <davej@codemonkey.org.uk> Suggested-by: Kirill A. Shutemov <kirill@shutemov.name> Signed-off-by: Hugh Dickins <hughd@google.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| * mm: fix pfn_t to page conversion in vm_insert_mixedDan Williams2016-01-311-2/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | pfn_t_to_page() honors the flags in the pfn_t value to determine if a pfn is backed by a page. However, vm_insert_mixed() was originally written to use pfn_valid() to make this determination. To restore the old/correct behavior, ignore the pfn_t flags in the !pfn_t_devmap() case and fallback to trusting pfn_valid(). Fixes: 01c8f1c44b83 ("mm, dax, gpu: convert vm_insert_mixed to pfn_t") Cc: Dave Hansen <dave@sr71.net> Cc: David Airlie <airlied@linux.ie> Reported-by: Tomi Valkeinen <tomi.valkeinen@ti.com> Tested-by: Tomi Valkeinen <tomi.valkeinen@ti.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
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