linux-kernel - Re: INFO: rcu detected stall in shrink_dcache

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Message-ID: <dc939a9c-80ef-ef8f-4e02-a46dbb736e89@I-love.SAKURA.ne.jp>
Date:   Sat, 14 Apr 2018 16:02:24 +0900
From:   Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
To:     syzbot <syzbot+8e4a81166025b5b7fa66@...kaller.appspotmail.com>,
        viro@...iv.linux.org.uk
Cc:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        syzkaller-bugs@...glegroups.com
Subject: Re: INFO: rcu detected stall in shrink_dcache_parent

Infinite loop inside shrink_dcache_parent() due to lack of cond_resched().
I can reproduce this issue by running the reproducer on one CPU (using "taskset -c 0").
Reverting commit 32785c0539b7e96f ("fs/dcache.c: add cond_resched() in shrink_dentry_list()")
solves this issue.

#syz dup: INFO: rcu detected stall in d_walk