From: Hugh Dickins <hughd@google.com>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: Hugh Dickins <hughd@google.com>,
Christian Brauner <brauner@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Baolin Wang <baolin.wang@linux.alibaba.com>,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org
Subject: Re: 6.19 tmpfs __d_lookup() lockup
Date: Thu, 11 Dec 2025 21:15:37 -0800 (PST) [thread overview]
Message-ID: <7f288332-5514-e2ed-69e2-50c5e0304d92@google.com> (raw)
In-Reply-To: <20251212050225.GD1712166@ZenIV>
On Fri, 12 Dec 2025, Al Viro wrote:
> On Thu, Dec 11, 2025 at 07:56:38PM -0800, Hugh Dickins wrote:
>
> > Of course, 2313598222f9 ("convert ramfs and tmpfs") (of Feb 26 2024!)
> > comes out as the first failing commit, no surprise there.
> >
> > I did try inserting a BUG_ON(node == node->next) on line 2438 of
> > fs/dcache.c, just after __d_lookup's hlist_bl_for_each_entry_rcu(),
> > and that BUG was immediately hit (but, for all I know, perhaps that's
> > an unreliable asserition, perhaps it's acceptable for a race to result
> > in a momentary node == node->next there).
>
> Hmm... Could you check if we are somehow hitting d_in_lookup(dentry)
> in d_make_persistent()?
Am I being stupid and misunderstanding you? I haven't tried
running with any printks, it seems obvious from the source that
d_make_persistent() always calls __d_instantiate(), which has a
WARN_ON(d_in_lookup(dentry)) at the start.
But I didn't see that warning fire on any occasion.
Hugh
next prev parent reply other threads:[~2025-12-12 5:15 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-12-12 3:56 Hugh Dickins
2025-12-12 5:02 ` Al Viro
2025-12-12 5:15 ` Hugh Dickins [this message]
2025-12-12 5:34 ` Al Viro
2025-12-12 5:57 ` Hugh Dickins
2025-12-12 6:30 ` Al Viro
2025-12-12 7:17 ` Hugh Dickins
2025-12-12 10:12 ` Hugh Dickins
2025-12-13 7:22 ` Al Viro
2025-12-14 3:27 ` shmem_rename() bugs (was Re: 6.19 tmpfs __d_lookup() lockup) Al Viro
2025-12-14 3:30 ` [PATCH 1/2] shmem_whiteout(): fix regression from tree-in-dcache series Al Viro
2025-12-14 3:30 ` [RFC][PATCH 2/2] shmem: fix recovery on rename failures Al Viro
2025-12-15 7:38 ` Hugh Dickins
2025-12-15 11:58 ` Christian Brauner
2025-12-15 16:03 ` Chuck Lever
2025-12-15 16:54 ` Al Viro
2025-12-16 6:02 ` [git pull] shmem rename fixes Al Viro
2025-12-16 8:04 ` pr-tracker-bot
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