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* blkcg: delay blkg destruction until after writeback has finishedDennis Zhou (Facebook)2018-08-311-0/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, blkcg destruction relies on a sequence of events: 1. Destruction starts. blkcg_css_offline() is called and blkgs release their reference to the blkcg. This immediately destroys the cgwbs (writeback). 2. With blkgs giving up their reference, the blkcg ref count should become zero and eventually call blkcg_css_free() which finally frees the blkcg. Jiufei Xue reported that there is a race between blkcg_bio_issue_check() and cgroup_rmdir(). To remedy this, blkg destruction becomes contingent on the completion of all writeback associated with the blkcg. A count of the number of cgwbs is maintained and once that goes to zero, blkg destruction can follow. This should prevent premature blkg destruction related to writeback. The new process for blkcg cleanup is as follows: 1. Destruction starts. blkcg_css_offline() is called which offlines writeback. Blkg destruction is delayed on the cgwb_refcnt count to avoid punting potentially large amounts of outstanding writeback to root while maintaining any ongoing policies. Here, the base cgwb_refcnt is put back. 2. When the cgwb_refcnt becomes zero, blkcg_destroy_blkgs() is called and handles destruction of blkgs. This is where the css reference held by each blkg is released. 3. Once the blkcg ref count goes to zero, blkcg_css_free() is called. This finally frees the blkg. It seems in the past blk-throttle didn't do the most understandable things with taking data from a blkg while associating with current. So, the simplification and unification of what blk-throttle is doing caused this. Fixes: 08e18eab0c579 ("block: add bi_blkg to the bio for cgroups") Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Dennis Zhou <dennisszhou@gmail.com> Cc: Jiufei Xue <jiufei.xue@linux.alibaba.com> Cc: Joseph Qi <joseph.qi@linux.alibaba.com> Cc: Tejun Heo <tj@kernel.org> Cc: Josef Bacik <josef@toxicpanda.com> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* bdi: use irqsave variant of refcount_dec_and_lock()Anna-Maria Gleixner2018-08-221-4/+1
| | | | | | | | | | | | | | | | | The irqsave variant of refcount_dec_and_lock handles irqsave/restore when taking/releasing the spin lock. With this variant the call of local_irq_save/restore is no longer required. [bigeasy@linutronix.de: s@atomic_dec_and_lock@refcount_dec_and_lock@g] Link: http://lkml.kernel.org/r/20180703200141.28415-5-bigeasy@linutronix.de Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* bdi: use refcount_t for reference counting instead atomic_tSebastian Andrzej Siewior2018-08-221-6/+6
| | | | | | | | | | | | | | | | | | refcount_t type and corresponding API should be used instead of atomic_t when the variable is used as a reference counter. This permits avoiding accidental refcounter overflows that might lead to use-after-free situations. Link: http://lkml.kernel.org/r/20180703200141.28415-4-bigeasy@linutronix.de Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Suggested-by: Peter Zijlstra <peterz@infradead.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* bdi: Fix another oops in wb_workfn()Jan Kara2018-06-221-13/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | syzbot is reporting NULL pointer dereference at wb_workfn() [1] due to wb->bdi->dev being NULL. And Dmitry confirmed that wb->state was WB_shutting_down after wb->bdi->dev became NULL. This indicates that unregister_bdi() failed to call wb_shutdown() on one of wb objects. The problem is in cgwb_bdi_unregister() which does cgwb_kill() and thus drops bdi's reference to wb structures before going through the list of wbs again and calling wb_shutdown() on each of them. This way the loop iterating through all wbs can easily miss a wb if that wb has already passed through cgwb_remove_from_bdi_list() called from wb_shutdown() from cgwb_release_workfn() and as a result fully shutdown bdi although wb_workfn() for this wb structure is still running. In fact there are also other ways cgwb_bdi_unregister() can race with cgwb_release_workfn() leading e.g. to use-after-free issues: CPU1 CPU2 cgwb_bdi_unregister() cgwb_kill(*slot); cgwb_release() queue_work(cgwb_release_wq, &wb->release_work); cgwb_release_workfn() wb = list_first_entry(&bdi->wb_list, ...) spin_unlock_irq(&cgwb_lock); wb_shutdown(wb); ... kfree_rcu(wb, rcu); wb_shutdown(wb); -> oops use-after-free We solve these issues by synchronizing writeback structure shutdown from cgwb_bdi_unregister() with cgwb_release_workfn() using a new mutex. That way we also no longer need synchronization using WB_shutting_down as the mutex provides it for CONFIG_CGROUP_WRITEBACK case and without CONFIG_CGROUP_WRITEBACK wb_shutdown() can be called only once from bdi_unregister(). Reported-by: syzbot <syzbot+4a7438e774b21ddd8eca@syzkaller.appspotmail.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* memcg: writeback: use memcg->cgwb_list directlyWang Long2018-06-081-2/+2
| | | | | | | | | | | | | | | | mem_cgroup_cgwb_list is a very simple wrapper and it will never be used outside of code under CONFIG_CGROUP_WRITEBACK. so use memcg->cgwb_list directly. Link: http://lkml.kernel.org/r/1524406173-212182-1-git-send-email-wanglong19@meituan.com Signed-off-by: Wang Long <wanglong19@meituan.com> Reviewed-by: Jan Kara <jack@suse.cz> Acked-by: Tejun Heo <tj@kernel.org> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* bdi: Move cgroup bdi_writeback to a dedicated low concurrency workqueueTejun Heo2018-05-231-1/+17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | From 0aa2e9b921d6db71150633ff290199554f0842a8 Mon Sep 17 00:00:00 2001 From: Tejun Heo <tj@kernel.org> Date: Wed, 23 May 2018 10:29:00 -0700 cgwb_release() punts the actual release to cgwb_release_workfn() on system_wq. Depending on the number of cgroups or block devices, there can be a lot of cgwb_release_workfn() in flight at the same time. We're periodically seeing close to 256 kworkers getting stuck with the following stack trace and overtime the entire system gets stuck. [<ffffffff810ee40c>] _synchronize_rcu_expedited.constprop.72+0x2fc/0x330 [<ffffffff810ee634>] synchronize_rcu_expedited+0x24/0x30 [<ffffffff811ccf23>] bdi_unregister+0x53/0x290 [<ffffffff811cd1e9>] release_bdi+0x89/0xc0 [<ffffffff811cd645>] wb_exit+0x85/0xa0 [<ffffffff811cdc84>] cgwb_release_workfn+0x54/0xb0 [<ffffffff810a68d0>] process_one_work+0x150/0x410 [<ffffffff810a71fd>] worker_thread+0x6d/0x520 [<ffffffff810ad3dc>] kthread+0x12c/0x160 [<ffffffff81969019>] ret_from_fork+0x29/0x40 [<ffffffffffffffff>] 0xffffffffffffffff The events leading to the lockup are... 1. A lot of cgwb_release_workfn() is queued at the same time and all system_wq kworkers are assigned to execute them. 2. They all end up calling synchronize_rcu_expedited(). One of them wins and tries to perform the expedited synchronization. 3. However, that invovles queueing rcu_exp_work to system_wq and waiting for it. Because #1 is holding all available kworkers on system_wq, rcu_exp_work can't be executed. cgwb_release_workfn() is waiting for synchronize_rcu_expedited() which in turn is waiting for cgwb_release_workfn() to free up some of the kworkers. We shouldn't be scheduling hundreds of cgwb_release_workfn() at the same time. There's nothing to be gained from that. This patch updates cgwb release path to use a dedicated percpu workqueue with @max_active of 1. While this resolves the problem at hand, it might be a good idea to isolate rcu_exp_work to its own workqueue too as it can be used from various paths and is prone to this sort of indirect A-A deadlocks. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Cc: stable@vger.kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
* bdi: Fix use after free bug in debugfs_remove()Tetsuo Handa2018-05-031-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | syzbot is reporting use after free bug in debugfs_remove() [1]. This is because fault injection made memory allocation for debugfs_create_file() from bdi_debug_register() from bdi_register_va() fail and continued with setting WB_registered. But when debugfs_remove() is called from debugfs_remove(bdi->debug_dir) from bdi_debug_unregister() from bdi_unregister() from release_bdi() because WB_registered was set by bdi_register_va(), IS_ERR_OR_NULL(bdi->debug_dir) == false despite debugfs_remove(bdi->debug_dir) was already called from bdi_register_va(). Fix this by making IS_ERR_OR_NULL(bdi->debug_dir) == true. [1] https://syzkaller.appspot.com/bug?id=5ab4efd91a96dcea9b68104f159adf4af2a6dfc1 Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Reported-by: syzbot <syzbot+049cb4ae097049dac137@syzkaller.appspotmail.com> Fixes: 97f07697932e6faf ("bdi: convert bdi_debug_register to int") Cc: weiping zhang <zhangweiping@didichuxing.com> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* bdi: wake up concurrent wb_shutdown() callers.Tetsuo Handa2018-05-031-1/+1
| | | | | | | | | | | | | | | | | | | | syzbot is reporting hung tasks at wait_on_bit(WB_shutting_down) in wb_shutdown() [1]. This seems to be because commit 5318ce7d46866e1d ("bdi: Shutdown writeback on all cgwbs in cgwb_bdi_destroy()") forgot to call wake_up_bit(WB_shutting_down) after clear_bit(WB_shutting_down). Introduce a helper function clear_and_wake_up_bit() and use it, in order to avoid similar errors in future. [1] https://syzkaller.appspot.com/bug?id=b297474817af98d5796bc544e1bb806fc3da0e5e Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Reported-by: syzbot <syzbot+c0cf869505e03bdf1a24@syzkaller.appspotmail.com> Fixes: 5318ce7d46866e1d ("bdi: Shutdown writeback on all cgwbs in cgwb_bdi_destroy()") Cc: Tejun Heo <tj@kernel.org> Reviewed-by: Jan Kara <jack@suse.cz> Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* mm/vmscan: don't mess with pgdat->flags in memcg reclaimAndrey Ryabinin2018-04-111-13/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | memcg reclaim may alter pgdat->flags based on the state of LRU lists in cgroup and its children. PGDAT_WRITEBACK may force kswapd to sleep congested_wait(), PGDAT_DIRTY may force kswapd to writeback filesystem pages. But the worst here is PGDAT_CONGESTED, since it may force all direct reclaims to stall in wait_iff_congested(). Note that only kswapd have powers to clear any of these bits. This might just never happen if cgroup limits configured that way. So all direct reclaims will stall as long as we have some congested bdi in the system. Leave all pgdat->flags manipulations to kswapd. kswapd scans the whole pgdat, only kswapd can clear pgdat->flags once node is balanced, thus it's reasonable to leave all decisions about node state to kswapd. Why only kswapd? Why not allow to global direct reclaim change these flags? It is because currently only kswapd can clear these flags. I'm less worried about the case when PGDAT_CONGESTED falsely not set, and more worried about the case when it falsely set. If direct reclaimer sets PGDAT_CONGESTED, do we have guarantee that after the congestion problem is sorted out, kswapd will be woken up and clear the flag? It seems like there is no such guarantee. E.g. direct reclaimers may eventually balance pgdat and kswapd simply won't wake up (see wakeup_kswapd()). Moving pgdat->flags manipulation to kswapd, means that cgroup2 recalim now loses its congestion throttling mechanism. Add per-cgroup congestion state and throttle cgroup2 reclaimers if memcg is in congestion state. Currently there is no need in per-cgroup PGDAT_WRITEBACK and PGDAT_DIRTY bits since they alter only kswapd behavior. The problem could be easily demonstrated by creating heavy congestion in one cgroup: echo "+memory" > /sys/fs/cgroup/cgroup.subtree_control mkdir -p /sys/fs/cgroup/congester echo 512M > /sys/fs/cgroup/congester/memory.max echo $$ > /sys/fs/cgroup/congester/cgroup.procs /* generate a lot of diry data on slow HDD */ while true; do dd if=/dev/zero of=/mnt/sdb/zeroes bs=1M count=1024; done & .... while true; do dd if=/dev/zero of=/mnt/sdb/zeroes bs=1M count=1024; done & and some job in another cgroup: mkdir /sys/fs/cgroup/victim echo 128M > /sys/fs/cgroup/victim/memory.max # time cat /dev/sda > /dev/null real 10m15.054s user 0m0.487s sys 1m8.505s According to the tracepoint in wait_iff_congested(), the 'cat' spent 50% of the time sleeping there. With the patch, cat don't waste time anymore: # time cat /dev/sda > /dev/null real 5m32.911s user 0m0.411s sys 0m56.664s [aryabinin@virtuozzo.com: congestion state should be per-node] Link: http://lkml.kernel.org/r/20180406135215.10057-1-aryabinin@virtuozzo.com [ayabinin@virtuozzo.com: make congestion state per-cgroup-per-node instead of just per-cgroup[ Link: http://lkml.kernel.org/r/20180406180254.8970-2-aryabinin@virtuozzo.com Link: http://lkml.kernel.org/r/20180323152029.11084-5-aryabinin@virtuozzo.com Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Tejun Heo <tj@kernel.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Steven Rostedt <rostedt@goodmis.org> 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 Torvalds2018-04-061-12/+1
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Merge updates from Andrew Morton: - a few misc things - ocfs2 updates - the v9fs maintainers have been missing for a long time. I've taken over v9fs patch slinging. - most of MM * emailed patches from Andrew Morton <akpm@linux-foundation.org>: (116 commits) mm,oom_reaper: check for MMF_OOM_SKIP before complaining mm/ksm: fix interaction with THP mm/memblock.c: cast constant ULLONG_MAX to phys_addr_t headers: untangle kmemleak.h from mm.h include/linux/mmdebug.h: make VM_WARN* non-rvals mm/page_isolation.c: make start_isolate_page_range() fail if already isolated mm: change return type to vm_fault_t mm, oom: remove 3% bonus for CAP_SYS_ADMIN processes mm, page_alloc: wakeup kcompactd even if kswapd cannot free more memory kernel/fork.c: detect early free of a live mm mm: make counting of list_lru_one::nr_items lockless mm/swap_state.c: make bool enable_vma_readahead and swap_vma_readahead() static block_invalidatepage(): only release page if the full page was invalidated mm: kernel-doc: add missing parameter descriptions mm/swap.c: remove @cold parameter description for release_pages() mm/nommu: remove description of alloc_vm_area zram: drop max_zpage_size and use zs_huge_class_size() zsmalloc: introduce zs_huge_class_size() mm: fix races between swapoff and flush dcache fs/direct-io.c: minor cleanups in do_blockdev_direct_IO ...
| * mm: reuse DEFINE_SHOW_ATTRIBUTE() macroAndy Shevchenko2018-04-061-12/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | ...instead of open coding file operations followed by custom ->open() callbacks per each attribute. [andriy.shevchenko@linux.intel.com: add tags, fix compilation issue] Link: http://lkml.kernel.org/r/20180217144253.58604-1-andriy.shevchenko@linux.intel.com Link: http://lkml.kernel.org/r/20180214154644.54505-1-andriy.shevchenko@linux.intel.com Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Reviewed-by: Matthew Wilcox <mawilcox@microsoft.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Acked-by: Christoph Lameter <cl@linux.com> Cc: Tejun Heo <tj@kernel.org> Cc: Dennis Zhou <dennisszhou@gmail.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | writeback: remove dead code in wb_blkcg/memcg_offlineJiufei Xue2018-02-281-2/+0
|/ | | | | | Signed-off-by: Jiufei Xue <jiufei.xue@linux.alibaba.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* Revert "bdi: add error handle for bdi_debug_register"Jens Axboe2017-12-211-4/+1
| | | | | | | | | | | | This reverts commit a0747a859ef6d3cc5b6cd50eb694499b78dd0025. It breaks some booting for some users, and more than a week into this, there's still no good fix. Revert this commit for now until a solution has been found. Reported-by: Laura Abbott <labbott@redhat.com> Reported-by: Bruno Wolff III <bruno@wolff.to> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* bdi: add error handle for bdi_debug_registerweiping zhang2017-11-191-1/+4
| | | | | | | | | | In order to make error handle more cleaner we call bdi_debug_register before set state to WB_registered, that we can avoid call bdi_unregister in release_bdi(). Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: weiping zhang <zhangweiping@didichuxing.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* bdi: convert bdi_debug_register to intweiping zhang2017-11-191-2/+15
| | | | | | | | Convert bdi_debug_register to int and then do error handle for it. Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: weiping zhang <zhangweiping@didichuxing.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* backing-dev: kill unused pdflush_proc_obsolete()Jens Axboe2017-10-061-20/+0
| | | | | | | | After commit b35bd0d9f8a8, pdflush_proc_obsolete() is no longer used. Kill the function and declaration. Reported-by: Rakesh Pandit <rakesh@tuxera.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* mm/backing-dev.c: fix an error handling path in 'cgwb_create()'Christophe JAILLET2017-09-111-2/+4
| | | | | | | | | | If the 'kmalloc' fails, we must go through the existing error handling path. Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr> Fixes: 52ebea749aae ("writeback: make backing_dev_info host cgroup-specific bdi_writebacks") Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* bdi: Drop 'parent' argument from bdi_register[_va]()Jan Kara2017-04-201-8/+5
| | | | | | | | | Drop 'parent' argument of bdi_register() and bdi_register_va(). It is always NULL. Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com>
* block: Remove unused functionsJan Kara2017-04-201-50/+6
| | | | | | | | | Now that all backing_dev_info structure are allocated separately, we can drop some unused functions. Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com>
* bdi: Export bdi_alloc_node() and bdi_put()Jan Kara2017-04-201-0/+2
| | | | | | | | | MTD will want to call bdi_alloc_node() and bdi_put() directly. Export these functions. Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com>
* block: Unregister bdi on last reference dropJan Kara2017-04-201-0/+2
| | | | | | | | | | | | Most users will want to unregister bdi when dropping last reference to a bdi. Only a few users (like block devices) want to play more complex tricks with bdi registration and unregistration. So unregister bdi when the last reference to bdi is dropped and just make sure we don't unregister the bdi the second time if it is already unregistered. Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com>
* bdi: Provide bdi_register_va() and bdi_alloc()Jan Kara2017-04-201-5/+15
| | | | | | | | | | | Add function that registers bdi and takes va_list instead of variable number of arguments. Add bdi_alloc() as simple wrapper for NUMA-unaware users allocating BDI. Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com>
* bdi: Rename cgwb_bdi_destroy() to cgwb_bdi_unregister()Jan Kara2017-03-231-3/+3
| | | | | | | | | | Rename cgwb_bdi_destroy() to cgwb_bdi_unregister() as it gets called from bdi_unregister() which is not necessarily called from bdi_destroy() and thus the name is somewhat misleading. Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com>
* bdi: Do not wait for cgwbs release in bdi_unregister()Jan Kara2017-03-231-21/+1
| | | | | | | | | | | | Currently we wait for all cgwbs to get released in cgwb_bdi_destroy() (called from bdi_unregister()). That is however unnecessary now when cgwb->bdi is a proper refcounted reference (thus bdi cannot get released before all cgwbs are released) and when cgwb_bdi_destroy() shuts down writeback directly. Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com>
* bdi: Shutdown writeback on all cgwbs in cgwb_bdi_destroy()Jan Kara2017-03-231-0/+22
| | | | | | | | | | | | | | | Currently we waited for all cgwbs to get freed in cgwb_bdi_destroy() which also means that writeback has been shutdown on them. Since this wait is going away, directly shutdown writeback on cgwbs from cgwb_bdi_destroy() to avoid live writeback structures after bdi_unregister() has finished. To make that safe with concurrent shutdown from cgwb_release_workfn(), we also have to make sure wb_shutdown() returns only after the bdi_writeback structure is really shutdown. Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com>
* bdi: Unify bdi->wb_list handling for root wb_writebackJan Kara2017-03-231-6/+28
| | | | | | | | | | | | | | | | | Currently root wb_writeback structure is added to bdi->wb_list in bdi_init() and never removed. That is different from all other wb_writeback structures which get added to the list when created and removed from it before wb_shutdown(). So move list addition of root bdi_writeback to bdi_register() and list removal of all wb_writeback structures to wb_shutdown(). That way a wb_writeback structure is on bdi->wb_list if and only if it can handle writeback and it will make it easier for us to handle shutdown of all wb_writeback structures in bdi_unregister(). Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com>
* bdi: Make wb->bdi a proper referenceJan Kara2017-03-231-2/+11
| | | | | | | | | | Make wb->bdi a proper refcounted reference to bdi for all bdi_writeback structures except for the one embedded inside struct backing_dev_info. That will allow us to simplify bdi unregistration. Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com>
* bdi: Mark congested->bdi as internalJan Kara2017-03-231-5/+5
| | | | | | | | | | | | | | | | | | | congested->bdi pointer is used only to be able to remove congested structure from bdi->cgwb_congested_tree on structure release. Moreover the pointer can become NULL when we unregister the bdi. Rename the field to __bdi and add a comment to make it more explicit this is internal stuff of memcg writeback code and people should not use the field as such use will be likely race prone. We do not bother with converting congested->bdi to a proper refcounted reference. It will be slightly ugly to special-case bdi->wb.congested to avoid effectively a cyclic reference of bdi to itself and the reference gets cleared from bdi_unregister() making it impossible to reference a freed bdi. Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com>
* bdi: Fix use-after-free in wb_congested_put()Jan Kara2017-03-081-15/+21
| | | | | | | | | | | | | | | | | | | | | | | | | | | bdi_writeback_congested structures get created for each blkcg and bdi regardless whether bdi is registered or not. When they are created in unregistered bdi and the request queue (and thus bdi) is then destroyed while blkg still holds reference to bdi_writeback_congested structure, this structure will be referencing freed bdi and last wb_congested_put() will try to remove the structure from already freed bdi. With commit 165a5e22fafb "block: Move bdi_unregister() to del_gendisk()", SCSI started to destroy bdis without calling bdi_unregister() first (previously it was calling bdi_unregister() even for unregistered bdis) and thus the code detaching bdi_writeback_congested in cgwb_bdi_destroy() was not triggered and we started hitting this use-after-free bug. It is enough to boot a KVM instance with virtio-scsi device to trigger this behavior. Fix the problem by detaching bdi_writeback_congested structures in bdi_exit() instead of bdi_unregister(). This is also more logical as they can get attached to bdi regardless whether it ever got registered or not. Fixes: 165a5e22fafb127ecb5914e12e8c32a1f0d3f820 Signed-off-by: Jan Kara <jack@suse.cz> Tested-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* block: Allow bdi re-registrationJan Kara2017-03-081-0/+7
| | | | | | | | | | | | | | | | | | | | | | | | SCSI can call device_add_disk() several times for one request queue when a device in unbound and bound, creating new gendisk each time. This will lead to bdi being repeatedly registered and unregistered. This was not a big problem until commit 165a5e22fafb "block: Move bdi_unregister() to del_gendisk()" since bdi was only registered repeatedly (bdi_register() handles repeated calls fine, only we ended up leaking reference to gendisk due to overwriting bdi->owner) but unregistered only in blk_cleanup_queue() which didn't get called repeatedly. After 165a5e22fafb we were doing correct bdi_register() - bdi_unregister() cycles however bdi_unregister() is not prepared for it. So make sure bdi_unregister() cleans up bdi in such a way that it is prepared for a possible following bdi_register() call. An easy way to provoke this behavior is to enable CONFIG_DEBUG_TEST_DRIVER_REMOVE and use scsi_debug driver to create a scsi disk which immediately hangs without this fix. Fixes: 165a5e22fafb127ecb5914e12e8c32a1f0d3f820 Signed-off-by: Jan Kara <jack@suse.cz> Tested-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* mm/backing-dev.c: use rb_entry()Geliang Tang2017-02-231-2/+2
| | | | | | | | | | | | To make the code clearer, use rb_entry() instead of container_of() to deal with rbtree. Link: http://lkml.kernel.org/r/671275de093d93ddc7c6f77ddc0d357149691a39.1484306840.git.geliangtang@gmail.com Signed-off-by: Geliang Tang <geliangtang@gmail.com> Cc: Jens Axboe <axboe@fb.com> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* block: fix double-free in the failure path of cgwb_bdi_init()Tejun Heo2017-02-081-2/+7
| | | | | | | | | | | | | | | | | | | | | | When !CONFIG_CGROUP_WRITEBACK, bdi has single bdi_writeback_congested at bdi->wb_congested. cgwb_bdi_init() allocates it with kzalloc() and doesn't do further initialization. This usually works fine as the reference count gets bumped to 1 by wb_init() and the put from wb_exit() releases it. However, when wb_init() fails, it puts the wb base ref automatically freeing the wb and the explicit kfree() in cgwb_bdi_init() error path ends up trying to free the same pointer the second time causing a double-free. Fix it by explicitly initilizing the refcnt to 1 and putting the base ref from cgwb_bdi_destroy(). Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Dmitry Vyukov <dvyukov@google.com> Fixes: a13f35e87140 ("writeback: don't embed root bdi_writeback_congested in bdi_writeback") Cc: stable@vger.kernel.org # v4.2+ Signed-off-by: Jens Axboe <axboe@fb.com>
* block: Dynamically allocate and refcount backing_dev_infoJan Kara2017-02-021-1/+33
| | | | | | | | | | | Instead of storing backing_dev_info inside struct request_queue, allocate it dynamically, reference count it, and free it when the last reference is dropped. Currently only request_queue holds the reference but in the following patch we add other users referencing backing_dev_info. Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com>
* writeback: track if we're sleeping on progress in balance_dirty_pages()Jens Axboe2016-11-081-0/+1
| | | | | | | | | Note in the bdi_writeback structure whenever a task ends up sleeping waiting for progress. We can use that information in the lower layers to increase the priority of writes. Signed-off-by: Jens Axboe <axboe@fb.com> Reviewed-by: Jan Kara <jack@suse.cz>
* block: fix bdi vs gendisk lifetime mismatchDan Williams2016-08-041-0/+19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The name for a bdi of a gendisk is derived from the gendisk's devt. However, since the gendisk is destroyed before the bdi it leaves a window where a new gendisk could dynamically reuse the same devt while a bdi with the same name is still live. Arrange for the bdi to hold a reference against its "owner" disk device while it is registered. Otherwise we can hit sysfs duplicate name collisions like the following: WARNING: CPU: 10 PID: 2078 at fs/sysfs/dir.c:31 sysfs_warn_dup+0x64/0x80 sysfs: cannot create duplicate filename '/devices/virtual/bdi/259:1' Hardware name: HP ProLiant DL580 Gen8, BIOS P79 05/06/2015 0000000000000286 0000000002c04ad5 ffff88006f24f970 ffffffff8134caec ffff88006f24f9c0 0000000000000000 ffff88006f24f9b0 ffffffff8108c351 0000001f0000000c ffff88105d236000 ffff88105d1031e0 ffff8800357427f8 Call Trace: [<ffffffff8134caec>] dump_stack+0x63/0x87 [<ffffffff8108c351>] __warn+0xd1/0xf0 [<ffffffff8108c3cf>] warn_slowpath_fmt+0x5f/0x80 [<ffffffff812a0d34>] sysfs_warn_dup+0x64/0x80 [<ffffffff812a0e1e>] sysfs_create_dir_ns+0x7e/0x90 [<ffffffff8134faaa>] kobject_add_internal+0xaa/0x320 [<ffffffff81358d4e>] ? vsnprintf+0x34e/0x4d0 [<ffffffff8134ff55>] kobject_add+0x75/0xd0 [<ffffffff816e66b2>] ? mutex_lock+0x12/0x2f [<ffffffff8148b0a5>] device_add+0x125/0x610 [<ffffffff8148b788>] device_create_groups_vargs+0xd8/0x100 [<ffffffff8148b7cc>] device_create_vargs+0x1c/0x20 [<ffffffff811b775c>] bdi_register+0x8c/0x180 [<ffffffff811b7877>] bdi_register_dev+0x27/0x30 [<ffffffff813317f5>] add_disk+0x175/0x4a0 Cc: <stable@vger.kernel.org> Reported-by: Yi Zhang <yizhan@redhat.com> Tested-by: Yi Zhang <yizhan@redhat.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Fixed up missing 0 return in bdi_register_owner(). Signed-off-by: Jens Axboe <axboe@fb.com>
* mm, vmscan: move LRU lists to nodeMel Gorman2016-07-291-7/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This moves the LRU lists from the zone to the node and related data such as counters, tracing, congestion tracking and writeback tracking. Unfortunately, due to reclaim and compaction retry logic, it is necessary to account for the number of LRU pages on both zone and node logic. Most reclaim logic is based on the node counters but the retry logic uses the zone counters which do not distinguish inactive and active sizes. It would be possible to leave the LRU counters on a per-zone basis but it's a heavier calculation across multiple cache lines that is much more frequent than the retry checks. Other than the LRU counters, this is mostly a mechanical patch but note that it introduces a number of anomalies. For example, the scans are per-zone but using per-node counters. We also mark a node as congested when a zone is congested. This causes weird problems that are fixed later but is easier to review. In the event that there is excessive overhead on 32-bit systems due to the nodes being on LRU then there are two potential solutions 1. Long-term isolation of highmem pages when reclaim is lowmem When pages are skipped, they are immediately added back onto the LRU list. If lowmem reclaim persisted for long periods of time, the same highmem pages get continually scanned. The idea would be that lowmem keeps those pages on a separate list until a reclaim for highmem pages arrives that splices the highmem pages back onto the LRU. It potentially could be implemented similar to the UNEVICTABLE list. That would reduce the skip rate with the potential corner case is that highmem pages have to be scanned and reclaimed to free lowmem slab pages. 2. Linear scan lowmem pages if the initial LRU shrink fails This will break LRU ordering but may be preferable and faster during memory pressure than skipping LRU pages. Link: http://lkml.kernel.org/r/1467970510-21195-4-git-send-email-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Minchan Kim <minchan@kernel.org> 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: throttle on IO only when there are too many dirty and writeback pagesMichal Hocko2016-05-211-17/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | wait_iff_congested has been used to throttle allocator before it retried another round of direct reclaim to allow the writeback to make some progress and prevent reclaim from looping over dirty/writeback pages without making any progress. We used to do congestion_wait before commit 0e093d99763e ("writeback: do not sleep on the congestion queue if there are no congested BDIs or if significant congestion is not being encountered in the current zone") but that led to undesirable stalls and sleeping for the full timeout even when the BDI wasn't congested. Hence wait_iff_congested was used instead. But it seems that even wait_iff_congested doesn't work as expected. We might have a small file LRU list with all pages dirty/writeback and yet the bdi is not congested so this is just a cond_resched in the end and can end up triggering pre mature OOM. This patch replaces the unconditional wait_iff_congested by congestion_wait which is executed only if we _know_ that the last round of direct reclaim didn't make any progress and dirty+writeback pages are more than a half of the reclaimable pages on the zone which might be usable for our target allocation. This shouldn't reintroduce stalls fixed by 0e093d99763e because congestion_wait is called only when we are getting hopeless when sleeping is a better choice than OOM with many pages under IO. We have to preserve logic introduced by commit 373ccbe59270 ("mm, vmstat: allow WQ concurrency to discover memory reclaim doesn't make any progress") into the __alloc_pages_slowpath now that wait_iff_congested is not used anymore. As the only remaining user of wait_iff_congested is shrink_inactive_list we can remove the WQ specific short sleep from wait_iff_congested because the sleep is needed to be done only once in the allocation retry cycle. [mhocko@suse.com: high_zoneidx->ac_classzone_idx to evaluate memory reserves properly] Link: http://lkml.kernel.org/r/1463051677-29418-2-git-send-email-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Joonsoo Kim <js1304@gmail.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Vladimir Davydov <vdavydov@virtuozzo.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* writeback: fix the wrong congested state variable definitionKaixu Xia2016-03-311-2/+2
| | | | | | | | | The right variable definition should be wb_congested_state that include WB_async_congested and WB_sync_congested. So fix it. Signed-off-by: Kaixu Xia <xiakaixu@huawei.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Jens Axboe <axboe@fb.com>
* mm: convert printk(KERN_<LEVEL> to pr_<level>Joe Perches2016-03-171-2/+2
| | | | | | | | | | | | | | | | 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/backing-dev.c: fix error path in wb_init()Rasmus Villemoes2016-02-121-1/+1
| | | | | | | | | | | | | We need to use post-decrement to get percpu_counter_destroy() called on &wb->stat[0]. Moreover, the pre-decremebt would cause infinite out-of-bounds accesses if the setup code failed at i==0. Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Vladimir Davydov <vdavydov@virtuozzo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, vmstat: fix wrong WQ sleep when memory reclaim doesn't make any progressTetsuo Handa2016-02-061-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Jan Stancek has reported that system occasionally hanging after "oom01" testcase from LTP triggers OOM. Guessing from a result that there is a kworker thread doing memory allocation and the values between "Node 0 Normal free:" and "Node 0 Normal:" differs when hanging, vmstat is not up-to-date for some reason. According to commit 373ccbe59270 ("mm, vmstat: allow WQ concurrency to discover memory reclaim doesn't make any progress"), it meant to force the kworker thread to take a short sleep, but it by error used schedule_timeout(1). We missed that schedule_timeout() in state TASK_RUNNING doesn't do anything. Fix it by using schedule_timeout_uninterruptible(1) which forces the kworker thread to take a short sleep in order to make sure that vmstat is up-to-date. Fixes: 373ccbe59270 ("mm, vmstat: allow WQ concurrency to discover memory reclaim doesn't make any progress") Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Reported-by: Jan Stancek <jstancek@redhat.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Tejun Heo <tj@kernel.org> Cc: Cristopher Lameter <clameter@sgi.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Arkadiusz Miskiewicz <arekm@maven.pl> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: memcontrol: export root_mem_cgroupJohannes Weiner2016-01-151-1/+1
| | | | | | | | | | | | A later patch will need this symbol in files other than memcontrol.c, so export it now and replace mem_cgroup_root_css at the same time. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: David S. Miller <davem@davemloft.net> Reviewed-by: Vladimir Davydov <vdavydov@virtuozzo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, vmstat: allow WQ concurrency to discover memory reclaim doesn't make any ↵Michal Hocko2015-12-121-3/+16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | progress Tetsuo Handa has reported that the system might basically livelock in OOM condition without triggering the OOM killer. The issue is caused by internal dependency of the direct reclaim on vmstat counter updates (via zone_reclaimable) which are performed from the workqueue context. If all the current workers get assigned to an allocation request, though, they will be looping inside the allocator trying to reclaim memory but zone_reclaimable can see stalled numbers so it will consider a zone reclaimable even though it has been scanned way too much. WQ concurrency logic will not consider this situation as a congested workqueue because it relies that worker would have to sleep in such a situation. This also means that it doesn't try to spawn new workers or invoke the rescuer thread if the one is assigned to the queue. In order to fix this issue we need to do two things. First we have to let wq concurrency code know that we are in trouble so we have to do a short sleep. In order to prevent from issues handled by 0e093d99763e ("writeback: do not sleep on the congestion queue if there are no congested BDIs or if significant congestion is not being encountered in the current zone") we limit the sleep only to worker threads which are the ones of the interest anyway. The second thing to do is to create a dedicated workqueue for vmstat and mark it WQ_MEM_RECLAIM to note it participates in the reclaim and to have a spare worker thread for it. Signed-off-by: Michal Hocko <mhocko@suse.com> Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Tejun Heo <tj@kernel.org> Cc: Cristopher Lameter <clameter@sgi.com> Cc: Joonsoo Kim <js1304@gmail.com> Cc: Arkadiusz Miskiewicz <arekm@maven.pl> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm, page_alloc: distinguish between being unable to sleep, unwilling to ↵Mel Gorman2015-11-071-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | sleep and avoiding waking kswapd __GFP_WAIT has been used to identify atomic context in callers that hold spinlocks or are in interrupts. They are expected to be high priority and have access one of two watermarks lower than "min" which can be referred to as the "atomic reserve". __GFP_HIGH users get access to the first lower watermark and can be called the "high priority reserve". Over time, callers had a requirement to not block when fallback options were available. Some have abused __GFP_WAIT leading to a situation where an optimisitic allocation with a fallback option can access atomic reserves. This patch uses __GFP_ATOMIC to identify callers that are truely atomic, cannot sleep and have no alternative. High priority users continue to use __GFP_HIGH. __GFP_DIRECT_RECLAIM identifies callers that can sleep and are willing to enter direct reclaim. __GFP_KSWAPD_RECLAIM to identify callers that want to wake kswapd for background reclaim. __GFP_WAIT is redefined as a caller that is willing to enter direct reclaim and wake kswapd for background reclaim. This patch then converts a number of sites o __GFP_ATOMIC is used by callers that are high priority and have memory pools for those requests. GFP_ATOMIC uses this flag. o Callers that have a limited mempool to guarantee forward progress clear __GFP_DIRECT_RECLAIM but keep __GFP_KSWAPD_RECLAIM. bio allocations fall into this category where kswapd will still be woken but atomic reserves are not used as there is a one-entry mempool to guarantee progress. o Callers that are checking if they are non-blocking should use the helper gfpflags_allow_blocking() where possible. This is because checking for __GFP_WAIT as was done historically now can trigger false positives. Some exceptions like dm-crypt.c exist where the code intent is clearer if __GFP_DIRECT_RECLAIM is used instead of the helper due to flag manipulations. o Callers that built their own GFP flags instead of starting with GFP_KERNEL and friends now also need to specify __GFP_KSWAPD_RECLAIM. The first key hazard to watch out for is callers that removed __GFP_WAIT and was depending on access to atomic reserves for inconspicuous reasons. In some cases it may be appropriate for them to use __GFP_HIGH. The second key hazard is callers that assembled their own combination of GFP flags instead of starting with something like GFP_KERNEL. They may now wish to specify __GFP_KSWAPD_RECLAIM. It's almost certainly harmless if it's missed in most cases as other activity will wake kswapd. Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Vitaly Wool <vitalywool@gmail.com> 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>
* writeback: remove broken rbtree_postorder_for_each_entry_safe() usage in ↵Tejun Heo2015-10-211-4/+6
| | | | | | | | | | | | | | | | cgwb_bdi_destroy() a20135ffbc44 ("writeback: don't drain bdi_writeback_congested on bdi destruction") added rbtree_postorder_for_each_entry_safe() which is used to remove all entries; however, according to Cody, the iterator isn't safe against operations which may rebalance the tree. Fix it by switching to repeatedly removing rb_first() until empty. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Cody P Schafer <dev@codyps.com> Fixes: a20135ffbc44 ("writeback: don't drain bdi_writeback_congested on bdi destruction") Link: http://lkml.kernel.org/g/1443997973-1700-1-git-send-email-dev@codyps.com Signed-off-by: Jens Axboe <axboe@fb.com>
* block: don't release bdi while request_queue has live referencesTejun Heo2015-10-151-1/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | bdi's are initialized in two steps, bdi_init() and bdi_register(), but destroyed in a single step by bdi_destroy() which, for a bdi embedded in a request_queue, is called during blk_cleanup_queue() which makes the queue invisible and starts the draining of remaining usages. A request_queue's user can access the congestion state of the embedded bdi as long as it holds a reference to the queue. As such, it may access the congested state of a queue which finished blk_cleanup_queue() but hasn't reached blk_release_queue() yet. Because the congested state was embedded in backing_dev_info which in turn is embedded in request_queue, accessing the congested state after bdi_destroy() was called was fine. The bdi was destroyed but the memory region for the congested state remained accessible till the queue got released. a13f35e87140 ("writeback: don't embed root bdi_writeback_congested in bdi_writeback") changed the situation. Now, the root congested state which is expected to be pinned while request_queue remains accessible is separately reference counted and the base ref is put during bdi_destroy(). This means that the root congested state may go away prematurely while the queue is between bdi_dstroy() and blk_cleanup_queue(), which was detected by Andrey's KASAN tests. The root cause of this problem is that bdi doesn't distinguish the two steps of destruction, unregistration and release, and now the root congested state actually requires a separate release step. To fix the issue, this patch separates out bdi_unregister() and bdi_exit() from bdi_destroy(). bdi_unregister() is called from blk_cleanup_queue() and bdi_exit() from blk_release_queue(). bdi_destroy() is now just a simple wrapper calling the two steps back-to-back. While at it, the prototype of bdi_destroy() is moved right below bdi_setup_and_register() so that the counterpart operations are located together. Signed-off-by: Tejun Heo <tj@kernel.org> Fixes: a13f35e87140 ("writeback: don't embed root bdi_writeback_congested in bdi_writeback") Cc: stable@vger.kernel.org # v4.2+ Reported-and-tested-by: Andrey Konovalov <andreyknvl@google.com> Link: http://lkml.kernel.org/g/CAAeHK+zUJ74Zn17=rOyxacHU18SgCfC6bsYW=6kCY5GXJBwGfQ@mail.gmail.com Reviewed-by: Jan Kara <jack@suse.com> Reviewed-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* writeback: bdi_writeback iteration must not skip dying onesTejun Heo2015-10-121-1/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | bdi_for_each_wb() is used in several places to wake up or issue writeback work items to all wb's (bdi_writeback's) on a given bdi. The iteration is performed by walking bdi->cgwb_tree; however, the tree only indexes wb's which are currently active. For example, when a memcg gets associated with a different blkcg, the old wb is removed from the tree so that the new one can be indexed. The old wb starts dying from then on but will linger till all its inodes are drained. As these dying wb's may still host dirty inodes, writeback operations which affect all wb's must include them. bdi_for_each_wb() skipping dying wb's led to sync(2) missing and failing to sync the inodes belonging to those wb's. This patch adds a RCU protected @bdi->wb_list which lists all wb's beloinging to that bdi. wb's are added on creation and removed on release rather than on the start of destruction. bdi_for_each_wb() usages are replaced with list_for_each[_continue]_rcu() iterations over @bdi->wb_list and bdi_for_each_wb() and its helpers are removed. v2: Updated as per Jan. last_wb ref leak in bdi_split_work_to_wbs() fixed and unnecessary list head severing in cgwb_bdi_destroy() removed. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-and-tested-by: Artem Bityutskiy <dedekind1@gmail.com> Fixes: ebe41ab0c79d ("writeback: implement bdi_for_each_wb()") Link: http://lkml.kernel.org/g/1443012552.19983.209.camel@gmail.com Cc: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@fb.com>
* Merge branch 'for-4.3/blkcg' of git://git.kernel.dk/linux-blockLinus Torvalds2015-09-111-2/+2
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull blk-cg updates from Jens Axboe: "A bit later in the cycle, but this has been in the block tree for a a while. This is basically four patchsets from Tejun, that improve our buffered cgroup writeback. It was dependent on the other cgroup changes, but they went in earlier in this cycle. Series 1 is set of 5 patches that has cgroup writeback updates: - bdi_writeback iteration fix which could lead to some wb's being skipped or repeated during e.g. sync under memory pressure. - Simplification of wb work wait mechanism. - Writeback tracepoints updated to report cgroup. Series 2 is is a set of updates for the CFQ cgroup writeback handling: cfq has always charged all async IOs to the root cgroup. It didn't have much choice as writeback didn't know about cgroups and there was no way to tell who to blame for a given writeback IO. writeback finally grew support for cgroups and now tags each writeback IO with the appropriate cgroup to charge it against. This patchset updates cfq so that it follows the blkcg each bio is tagged with. Async cfq_queues are now shared across cfq_group, which is per-cgroup, instead of per-request_queue cfq_data. This makes all IOs follow the weight based IO resource distribution implemented by cfq. - Switched from GFP_ATOMIC to GFP_NOWAIT as suggested by Jeff. - Other misc review points addressed, acks added and rebased. Series 3 is the blkcg policy cleanup patches: This patchset contains assorted cleanups for blkcg_policy methods and blk[c]g_policy_data handling. - alloc/free added for blkg_policy_data. exit dropped. - alloc/free added for blkcg_policy_data. - blk-throttle's async percpu allocation is replaced with direct allocation. - all methods now take blk[c]g_policy_data instead of blkcg_gq or blkcg. And finally, series 4 is a set of patches cleaning up the blkcg stats handling: blkcg's stats have always been somwhat of a mess. This patchset tries to improve the situation a bit. - The following patches added to consolidate blkcg entry point and blkg creation. This is in itself is an improvement and helps colllecting common stats on bio issue. - per-blkg stats now accounted on bio issue rather than request completion so that bio based and request based drivers can behave the same way. The issue was spotted by Vivek. - cfq-iosched implements custom recursive stats and blk-throttle implements custom per-cpu stats. This patchset make blkcg core support both by default. - cfq-iosched and blk-throttle keep track of the same stats multiple times. Unify them" * 'for-4.3/blkcg' of git://git.kernel.dk/linux-block: (45 commits) blkcg: use CGROUP_WEIGHT_* scale for io.weight on the unified hierarchy blkcg: s/CFQ_WEIGHT_*/CFQ_WEIGHT_LEGACY_*/ blkcg: implement interface for the unified hierarchy blkcg: misc preparations for unified hierarchy interface blkcg: separate out tg_conf_updated() from tg_set_conf() blkcg: move body parsing from blkg_conf_prep() to its callers blkcg: mark existing cftypes as legacy blkcg: rename subsystem name from blkio to io blkcg: refine error codes returned during blkcg configuration blkcg: remove unnecessary NULL checks from __cfqg_set_weight_device() blkcg: reduce stack usage of blkg_rwstat_recursive_sum() blkcg: remove cfqg_stats->sectors blkcg: move io_service_bytes and io_serviced stats into blkcg_gq blkcg: make blkg_[rw]stat_recursive_sum() to be able to index into blkcg_gq blkcg: make blkcg_[rw]stat per-cpu blkcg: add blkg_[rw]stat->aux_cnt and replace cfq_group->dead_stats with it blkcg: consolidate blkg creation in blkcg_bio_issue_check() blk-throttle: improve queue bypass handling blkcg: move root blkg lookup optimization from throtl_lookup_tg() to __blkg_lookup() blkcg: inline [__]blkg_lookup() ...
| * blkcg: rename subsystem name from blkio to ioTejun Heo2015-08-191-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | blkio interface has become messy over time and is currently the largest. In addition to the inconsistent naming scheme, it has multiple stat files which report more or less the same thing, a number of debug stat files which expose internal details which shouldn't have been part of the public interface in the first place, recursive and non-recursive stats and leaf and non-leaf knobs. Both recursive vs. non-recursive and leaf vs. non-leaf distinctions don't make any sense on the unified hierarchy as only leaf cgroups can contain processes. cgroups is going through a major interface revision with the unified hierarchy involving significant fundamental usage changes and given that a significant portion of the interface doesn't make sense anymore, it's a good time to reorganize the interface. As the first step, this patch renames the external visible subsystem name from "blkio" to "io". This is more concise, matches the other two major subsystem names, "cpu" and "memory", and better suited as blkcg will be involved in anything writeback related too whether an actual block device is involved or not. As the subsystem legacy_name is set to "blkio", the only userland visible change outside the unified hierarchy is that blkcg is reported as "io" instead of "blkio" in the subsystem initialized message during boot. On the unified hierarchy, blkcg now appears as "io". Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Li Zefan <lizefan@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: cgroups@vger.kernel.org Signed-off-by: Jens Axboe <axboe@fb.com>
* | inode: rename i_wb_list to i_io_listDave Chinner2015-08-181-4/+4
|/ | | | | | | | | | | | | | | | | | | There's a small consistency problem between the inode and writeback naming. Writeback calls the "for IO" inode queues b_io and b_more_io, but the inode calls these the "writeback list" or i_wb_list. This makes it hard to an new "under writeback" list to the inode, or call it an "under IO" list on the bdi because either way we'll have writeback on IO and IO on writeback and it'll just be confusing. I'm getting confused just writing this! So, rename the inode "for IO" list variable to i_io_list so we can add a new "writeback list" in a subsequent patch. Signed-off-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Josef Bacik <jbacik@fb.com> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Christoph Hellwig <hch@lst.de> Tested-by: Dave Chinner <dchinner@redhat.com>
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-04 19:47:26 +0100