From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AIpwx49q5NuTu/pkar/9px7UWepYB2/CIZqgOOO6MdC/z3vciM+37ZI5Zb2wulls3/zKCSup4F+h ARC-Seal: i=1; a=rsa-sha256; t=1522168766; cv=none; d=google.com; s=arc-20160816; b=XIEkSeE0avzw8NwqT0HgA5wRUmm+u66rl6Uc7zyU1I2Yf7k65Uw4XXCKxiq210gzwV mL0xsxsdw1i1pAASSXGqnLaMso7vqp2+MVocwQDMM75yJWx4dYsRf9mtsv7Vz2v2ZL5W gO6Nllm4jHzBaIBoFAkl4WzFLcDZfbUetIVztrV61oA6kWUMfzkgPMFodCbdIrZUVlTx p3qvSr73+60Z2/O7J9GrU66BFCARCiS9Wa4zRiGfHFu9gRDxObRvkinIOaUgxamDRoek B/rcboEqEfRXzhG41ozdycdYveblVC1n3a2CuKgbt/X+ELLm3ihRktbQiCBhgMWU1X1H WAmw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=mime-version:user-agent:references:in-reply-to:message-id:date :subject:cc:to:from:arc-authentication-results; bh=rM7oGzG/5HM9VNO7W2V59bz+LLAmK0UmRy1kNypLVIw=; b=szIrL0CgMR84BgRWLfkYfX98u5BjUZig06YRs3PXUByXERtfeaYiBMF8aiSb0xw+9e WhDIBf4VZsp8BDyebbhqFNV8JcxYKEQG0eSWQV7+D77B4wqqAs28cnep4utprqHaiw0J cDGVeHVJZgLQ3ndmuLm0M0R+vMoVeNtecYJOevwZouU7+S5YonbONGbLIR+H6OJgHJx+ Bx/ZjY/ksw9noGnDZv49Xf7IOP3FBvLaVyAbstCGph7aO2ax0IrwEhpezd5KjJRQwXjR g0gfG6wOFVcg2GLOMmNPxUY8FMyKrgqmXKZ02BgoKfQS4Dawud3+I5jLv3O2d52vGdIF YIOA== ARC-Authentication-Results: i=1; mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.61.202 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.61.202 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Tetsuo Handa , Dave Jones , Peter Zijlstra , Nick Piggin , Ingo Molnar , Nikolay Borisov , Michal Hocko , Andrew Morton , Linus Torvalds Subject: [PATCH 4.15 024/105] lockdep: fix fs_reclaim warning Date: Tue, 27 Mar 2018 18:27:04 +0200 Message-Id: <20180327162758.890519461@linuxfoundation.org> X-Mailer: git-send-email 2.16.3 In-Reply-To: <20180327162757.813009222@linuxfoundation.org> References: <20180327162757.813009222@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-LABELS: =?utf-8?b?IlxcU2VudCI=?= X-GMAIL-THRID: =?utf-8?q?1596109440855505175?= X-GMAIL-MSGID: =?utf-8?q?1596109636988068897?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Tetsuo Handa commit 2e517d681632326ed98399cb4dd99519efe3e32c upstream. 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 Reported-by: Dave Jones Tested-by: Dave Jones Cc: Peter Zijlstra Cc: Nick Piggin Cc: Ingo Molnar Cc: Nikolay Borisov Cc: Michal Hocko Cc: [4.14+] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/page_alloc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -3588,7 +3588,7 @@ static bool __need_fs_reclaim(gfp_t gfp_ 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 */