From: Andrew Morton <akpm@linux-foundation.org>
To: Arjan van de Ven <arjan@linux.intel.com>
Cc: linux-mm@kvack.org,
syzbot+9722a25de70a85ff48a1@syzkaller.appspotmail.com,
baolin.wang@linux.alibaba.com, hughd@google.com,
linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com
Subject: Re: [syzbot] [mm?] BUG: sleeping function called from invalid context in shmem_undo_range
Date: Fri, 24 Apr 2026 03:42:42 -0700 [thread overview]
Message-ID: <20260424034242.b3e888872e8af6bedb882c1c@linux-foundation.org> (raw)
In-Reply-To: <20260424023524.322251-1-arjan@linux.intel.com>
On Thu, 23 Apr 2026 19:34:54 -0700 Arjan van de Ven <arjan@linux.intel.com> wrote:
> This email is created by automation to help kernel developers
> deal with a large volume of AI generated bug reports by decoding
> oopses into more actionable information.
Thanks ;)
>
> ...
>
> Potential Solution
>
> Find the rcu_read_lock() call that is missing its matching
> rcu_read_unlock() in the vfs_unlink() / fsnotify_unlink() /
> d_delete_notify() code path. Adding a WARN_ON(rcu_read_lock_held())
> to iput() (alongside the existing might_sleep() check) should produce
> a backtrace pointing at the exact acquisition site on the next
> reproduction.
yup, if we had a reproducer!
What's missing from the lockdep report is the one thing we want to know
- where did that rcu_read_lock() occur? All we have is
> #1: ffffffff8e7e5260 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire.constprop.0+0x7/0x30 include/linux/rcupdate.h:300
which isn't very useful! lockdep records the stack trace for the
acquisition site, so why didn't we get to see that?
prev parent reply other threads:[~2026-04-24 10:42 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-24 0:23 [syzbot] [mm?] BUG: sleeping function called from invalid context in shmem_undo_range syzbot
2026-04-24 2:34 ` Arjan van de Ven
2026-04-24 10:42 ` Andrew Morton [this message]
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