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From: Peter Zijlstra <>
To: Omar Sandoval <>
	Tetsuo Handa <>,
	Ingo Molnar <>,
	Linus Torvalds <>,
Subject: Re: [PATCH] lockdep: fix fs_reclaim annotation
Date: Fri, 20 Apr 2018 10:17:42 +0200	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On Sun, Apr 15, 2018 at 12:42:25AM -0700, Omar Sandoval wrote:
> From: Omar Sandoval <>
> While revisiting my Btrfs swapfile series [1], I introduced a situation
> in which reclaim would lock i_rwsem, and even though the swapon() path
> clearly made GFP_KERNEL allocations while holding i_rwsem, I got no
> complaints from lockdep. It turns out that the rework of the fs_reclaim
> annotation was broken: if the current task has PF_MEMALLOC set, we don't
> acquire the dummy fs_reclaim lock, but when reclaiming we always check
> this _after_ we've just set the PF_MEMALLOC flag. In most cases, we can
> fix this by moving the fs_reclaim_{acquire,release}() outside of the
> memalloc_noreclaim_{save,restore}(), althought kswapd is slightly
> different. After applying this, I got the expected lockdep splats.
> 1:
> Fixes: d92a8cfcb37e ("locking/lockdep: Rework FS_RECLAIM annotation")
> Signed-off-by: Omar Sandoval <>

Urgh, thanks for fixing that!

  reply	other threads:[~2018-04-20  8:18 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-15  7:42 Omar Sandoval
2018-04-20  8:17 ` Peter Zijlstra [this message]
2018-04-24 22:58   ` Omar Sandoval
2018-04-25  7:09     ` Peter Zijlstra

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