The patch titled Subject: memcg: mem_cgroup_migrate() may be called with irq disabled has been added to the -mm tree. Its filename is memcg-mem_cgroup_migrate-may-be-called-with-irq-disabled.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/memcg-mem_cgroup_migrate-may-be-called-with-irq-disabled.patch and later at http://ozlabs.org/~akpm/mmotm/broken-out/memcg-mem_cgroup_migrate-may-be-called-with-irq-disabled.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Tejun Heo <tj@xxxxxxxxxx> Subject: memcg: mem_cgroup_migrate() may be called with irq disabled mem_cgroup_migrate() uses local_irq_disable/enable() but can be called with irq disabled from migrate_page_copy(). This ends up enabling irq while holding a irq context lock triggering the following lockdep warning. Fix it by using irq_save/restore instead. ================================= [ INFO: inconsistent lock state ] 4.7.0-rc1+ #52 Tainted: G W --------------------------------- inconsistent {IN-SOFTIRQ-W} -> {SOFTIRQ-ON-W} usage. kcompactd0/151 [HC0[0]:SC0[0]:HE1:SE1] takes: (&(&ctx->completion_lock)->rlock){+.?.-.}, at: [<000000000038fd96>] aio_migratepage+0x156/0x1e8 {IN-SOFTIRQ-W} state was registered at: [<00000000001a8366>] __lock_acquire+0x5b6/0x1930 [<00000000001a9b9e>] lock_acquire+0xee/0x270 [<0000000000951fee>] _raw_spin_lock_irqsave+0x66/0xb0 [<0000000000390108>] aio_complete+0x98/0x328 [<000000000037c7d4>] dio_complete+0xe4/0x1e0 [<0000000000650e64>] blk_update_request+0xd4/0x450 [<000000000072a1a8>] scsi_end_request+0x48/0x1c8 [<000000000072d7e2>] scsi_io_completion+0x272/0x698 [<000000000065adb2>] blk_done_softirq+0xca/0xe8 [<0000000000953f80>] __do_softirq+0xc8/0x518 [<00000000001495de>] irq_exit+0xee/0x110 [<000000000010ceba>] do_IRQ+0x6a/0x88 [<000000000095342e>] io_int_handler+0x11a/0x25c [<000000000094fb5c>] __mutex_unlock_slowpath+0x144/0x1d8 [<000000000094fb58>] __mutex_unlock_slowpath+0x140/0x1d8 [<00000000003c6114>] kernfs_iop_permission+0x64/0x80 [<000000000033ba86>] __inode_permission+0x9e/0xf0 [<000000000033ea96>] link_path_walk+0x6e/0x510 [<000000000033f09c>] path_lookupat+0xc4/0x1a8 [<000000000034195c>] filename_lookup+0x9c/0x160 [<0000000000341b44>] user_path_at_empty+0x5c/0x70 [<0000000000335250>] SyS_readlinkat+0x68/0x140 [<0000000000952f8e>] system_call+0xd6/0x270 irq event stamp: 971410 hardirqs last enabled at (971409): [<000000000030f982>] migrate_page_move_mapping+0x3ea/0x588 hardirqs last disabled at (971410): [<0000000000951fc4>] _raw_spin_lock_irqsave+0x3c/0xb0 softirqs last enabled at (970526): [<0000000000954318>] __do_softirq+0x460/0x518 softirqs last disabled at (970519): [<00000000001495de>] irq_exit+0xee/0x110 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&(&ctx->completion_lock)->rlock); <Interrupt> lock(&(&ctx->completion_lock)->rlock); *** DEADLOCK *** 3 locks held by kcompactd0/151: #0: (&(&mapping->private_lock)->rlock){+.+.-.}, at: [<000000000038fc82>] aio_migratepage+0x42/0x1e8 #1: (&ctx->ring_lock){+.+.+.}, at: [<000000000038fc9a>] aio_migratepage+0x5a/0x1e8 #2: (&(&ctx->completion_lock)->rlock){+.?.-.}, at: [<000000000038fd96>] aio_migratepage+0x156/0x1e8 stack backtrace: CPU: 20 PID: 151 Comm: kcompactd0 Tainted: G W 4.7.0-rc1+ #52 00000001c6cbb730 00000001c6cbb7c0 0000000000000002 0000000000000000 00000001c6cbb860 00000001c6cbb7d8 00000001c6cbb7d8 0000000000114496 0000000000000000 0000000000b517ec 0000000000b680b6 000000000000000b 00000001c6cbb820 00000001c6cbb7c0 0000000000000000 0000000000000000 040000000184ad18 0000000000114496 00000001c6cbb7c0 00000001c6cbb820 Call Trace: ([<00000000001143d2>] show_trace+0xea/0xf0) ([<000000000011444a>] show_stack+0x72/0xf0) ([<0000000000684522>] dump_stack+0x9a/0xd8) ([<000000000028679c>] print_usage_bug.part.27+0x2d4/0x2e8) ([<00000000001a71ce>] mark_lock+0x17e/0x758) ([<00000000001a784a>] mark_held_locks+0xa2/0xd0) ([<00000000001a79b8>] trace_hardirqs_on_caller+0x140/0x1c0) ([<0000000000326026>] mem_cgroup_migrate+0x266/0x370) ([<000000000038fdaa>] aio_migratepage+0x16a/0x1e8) ([<0000000000310568>] move_to_new_page+0xb0/0x260) ([<00000000003111b4>] migrate_pages+0x8f4/0x9f0) ([<00000000002c507c>] compact_zone+0x4dc/0xdc8) ([<00000000002c5e22>] kcompactd_do_work+0x1aa/0x358) ([<00000000002c608a>] kcompactd+0xba/0x2c8) ([<000000000016b09a>] kthread+0x10a/0x110) ([<000000000095315a>] kernel_thread_starter+0x6/0xc) ([<0000000000953154>] kernel_thread_starter+0x0/0xc) INFO: lockdep is turned off. Link: http://lkml.kernel.org/r/20160620184158.GO3262@xxxxxxxxxxxxxxx Link: http://lkml.kernel.org/g/5767CFE5.7080904@xxxxxxxxxx Fixes: 74485cf2bc85 ("mm: migrate: consolidate mem_cgroup_migrate() calls") Signed-off-by: Tejun Heo <tj@xxxxxxxxxx> Reported-by: Christian Borntraeger <borntraeger@xxxxxxxxxx> Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxxxx> Cc: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> [4.5+] Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/memcontrol.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff -puN mm/memcontrol.c~memcg-mem_cgroup_migrate-may-be-called-with-irq-disabled mm/memcontrol.c --- a/mm/memcontrol.c~memcg-mem_cgroup_migrate-may-be-called-with-irq-disabled +++ a/mm/memcontrol.c @@ -5544,6 +5544,7 @@ void mem_cgroup_migrate(struct page *old struct mem_cgroup *memcg; unsigned int nr_pages; bool compound; + unsigned long flags; VM_BUG_ON_PAGE(!PageLocked(oldpage), oldpage); VM_BUG_ON_PAGE(!PageLocked(newpage), newpage); @@ -5574,10 +5575,10 @@ void mem_cgroup_migrate(struct page *old commit_charge(newpage, memcg, false); - local_irq_disable(); + local_irq_save(flags); mem_cgroup_charge_statistics(memcg, newpage, compound, nr_pages); memcg_check_events(memcg, newpage); - local_irq_enable(); + local_irq_restore(flags); } DEFINE_STATIC_KEY_FALSE(memcg_sockets_enabled_key); _ Patches currently in -mm which might be from tj@xxxxxxxxxx are memcg-mem_cgroup_migrate-may-be-called-with-irq-disabled.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html