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authorTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>2018-03-22 16:17:10 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-03-22 17:07:01 -0700
commit2e517d681632326ed98399cb4dd99519efe3e32c (patch)
tree76b6e6018b741a415a1469afc430b1381296be17
parent296cefee07a20c89c8008c32ea0421ca64caf358 (diff)
downloadlinux-stericsson-2e517d681632326ed98399cb4dd99519efe3e32c.tar.gz
lockdep: fix fs_reclaim warning
Dave Jones reported fs_reclaim lockdep warnings. ============================================ WARNING: possible recursive locking detected 4.15.0-rc9-backup-debug+ #1 Not tainted -------------------------------------------- sshd/24800 is trying to acquire lock: (fs_reclaim){+.+.}, at: [<0000000084f438c2>] fs_reclaim_acquire.part.102+0x5/0x30 but task is already holding lock: (fs_reclaim){+.+.}, at: [<0000000084f438c2>] fs_reclaim_acquire.part.102+0x5/0x30 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(fs_reclaim); lock(fs_reclaim); *** DEADLOCK *** May be due to missing lock nesting notation 2 locks held by sshd/24800: #0: (sk_lock-AF_INET6){+.+.}, at: [<000000001a069652>] tcp_sendmsg+0x19/0x40 #1: (fs_reclaim){+.+.}, at: [<0000000084f438c2>] fs_reclaim_acquire.part.102+0x5/0x30 stack backtrace: CPU: 3 PID: 24800 Comm: sshd Not tainted 4.15.0-rc9-backup-debug+ #1 Call Trace: dump_stack+0xbc/0x13f __lock_acquire+0xa09/0x2040 lock_acquire+0x12e/0x350 fs_reclaim_acquire.part.102+0x29/0x30 kmem_cache_alloc+0x3d/0x2c0 alloc_extent_state+0xa7/0x410 __clear_extent_bit+0x3ea/0x570 try_release_extent_mapping+0x21a/0x260 __btrfs_releasepage+0xb0/0x1c0 btrfs_releasepage+0x161/0x170 try_to_release_page+0x162/0x1c0 shrink_page_list+0x1d5a/0x2fb0 shrink_inactive_list+0x451/0x940 shrink_node_memcg.constprop.88+0x4c9/0x5e0 shrink_node+0x12d/0x260 try_to_free_pages+0x418/0xaf0 __alloc_pages_slowpath+0x976/0x1790 __alloc_pages_nodemask+0x52c/0x5c0 new_slab+0x374/0x3f0 ___slab_alloc.constprop.81+0x47e/0x5a0 __slab_alloc.constprop.80+0x32/0x60 __kmalloc_track_caller+0x267/0x310 __kmalloc_reserve.isra.40+0x29/0x80 __alloc_skb+0xee/0x390 sk_stream_alloc_skb+0xb8/0x340 tcp_sendmsg_locked+0x8e6/0x1d30 tcp_sendmsg+0x27/0x40 inet_sendmsg+0xd0/0x310 sock_write_iter+0x17a/0x240 __vfs_write+0x2ab/0x380 vfs_write+0xfb/0x260 SyS_write+0xb6/0x140 do_syscall_64+0x1e5/0xc05 entry_SYSCALL64_slow_path+0x25/0x25 This warning is caused by commit d92a8cfcb37e ("locking/lockdep: Rework FS_RECLAIM annotation") which replaced the use of lockdep_{set,clear}_current_reclaim_state() in __perform_reclaim() and lockdep_trace_alloc() in slab_pre_alloc_hook() with fs_reclaim_acquire()/ fs_reclaim_release(). Since __kmalloc_reserve() from __alloc_skb() adds __GFP_NOMEMALLOC | __GFP_NOWARN to gfp_mask, and all reclaim path simply propagates __GFP_NOMEMALLOC, fs_reclaim_acquire() in slab_pre_alloc_hook() is trying to grab the 'fake' lock again when __perform_reclaim() already grabbed the 'fake' lock. The /* this guy won't enter reclaim */ if ((current->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC)) return false; test which causes slab_pre_alloc_hook() to try to grab the 'fake' lock was added by commit cf40bd16fdad ("lockdep: annotate reclaim context (__GFP_NOFS)"). But that test is outdated because PF_MEMALLOC thread won't enter reclaim regardless of __GFP_NOMEMALLOC after commit 341ce06f69ab ("page allocator: calculate the alloc_flags for allocation only once") added the PF_MEMALLOC safeguard ( /* Avoid recursion of direct reclaim */ if (p->flags & PF_MEMALLOC) goto nopage; in __alloc_pages_slowpath()). Thus, let's fix outdated test by removing __GFP_NOMEMALLOC test and allow __need_fs_reclaim() to return false. Link: http://lkml.kernel.org/r/201802280650.FJC73911.FOSOMLJVFFQtHO@I-love.SAKURA.ne.jp Fixes: d92a8cfcb37ecd13 ("locking/lockdep: Rework FS_RECLAIM annotation") Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Reported-by: Dave Jones <davej@codemonkey.org.uk> Tested-by: Dave Jones <davej@codemonkey.org.uk> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Nick Piggin <npiggin@gmail.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Nikolay Borisov <nborisov@suse.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: <stable@vger.kernel.org> [4.14+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/page_alloc.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 635d7dd29d7f..010dee0f089e 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3596,7 +3596,7 @@ static bool __need_fs_reclaim(gfp_t gfp_mask)
return false;
/* this guy won't enter reclaim */
- if ((current->flags & PF_MEMALLOC) && !(gfp_mask & __GFP_NOMEMALLOC))
+ if (current->flags & PF_MEMALLOC)
return false;
/* We're only interested __GFP_FS allocations for now */