linux-kernel - Re: [PATCH] fs/dcache.c: re-add cond_resched() in shrink_dcache

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Message-ID: <alpine.DEB.2.21.1804131415190.214710@chino.kir.corp.google.com>
Date:   Fri, 13 Apr 2018 14:15:30 -0700 (PDT)
From:   David Rientjes <rientjes@...gle.com>
To:     Khazhismel Kumykov <khazhy@...gle.com>
cc:     nborisov@...e.com, akpm@...ux-foundation.org,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Goldwyn Rodrigues <rgoldwyn@...e.de>,
        Jeff Mahoney <jeffm@...e.com>,
        Davidlohr Bueso <dave@...olabs.net>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH] fs/dcache.c: re-add cond_resched() in
 shrink_dcache_parent()

On Fri, 13 Apr 2018, Khazhismel Kumykov wrote:

> shrink_dcache_parent may spin waiting for a parallel shrink_dentry_list.
> In this case we may have 0 dentries to dispose, so we will never
> schedule out while waiting for the parallel shrink_dentry_list to
> complete.
> 
> Tested that this fixes syzbot reports of stalls in shrink_dcache_parent()
> 
> Fixes: 32785c0539b7 ("fs/dcache.c: add cond_resched() in shrink_dentry_list()")
> Reported-by: syzbot+ae80b790eb412884ca77@...kaller.appspotmail.com
> 
> Cc: Nikolay Borisov <nborisov@...e.com>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: David Rientjes <rientjes@...gle.com>
> Cc: Alexander Viro <viro@...iv.linux.org.uk>
> Cc: Goldwyn Rodrigues <rgoldwyn@...e.de>
> Cc: Jeff Mahoney <jeffm@...e.com>
> Cc: Davidlohr Bueso <dave@...olabs.net>
> Cc: Linus Torvalds <torvalds@...ux-foundation.org>
> Signed-off-by: Khazhismel Kumykov <khazhy@...gle.com>

Acked-by: David Rientjes <rientjes@...gle.com>