linux-kernel - [RFC 0/1] fsnotify: clear PARENT

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Message-ID: <20250903093413.3434-1-lidiangang@bytedance.com>
Date: Wed,  3 Sep 2025 17:34:12 +0800
From: Diangang Li <lidiangang@...edance.com>
To: jack@...e.cz,
	amir73il@...il.com,
	stephen.s.brennan@...cle.com,
	changfengnan@...edance.com
Cc: linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Diangang Li <lidiangang@...edance.com>
Subject: [RFC 0/1] fsnotify: clear PARENT_WATCHED flags lazily for v5.4

Hi Amir, Jan, et al,

Commit `41f49be2e51a71` ("fsnotify: clear PARENT_WATCHED flags lazily")
has resolved the softlockup in `__fsnotify_parent` when there are millions
of negative dentries. The Linux kernel CVE team has assigned CVE-2024-47660
to this issue[1]. I noticed that the CVE patch was only backported to the
5.10 stable tree, and not to 5.4. Is there any specific reason or analysis
regarding the 5.4 branch? We have encountered this issue in our production
environments running kernel 5.4. After manually applying and deconflicting
this patch, the problem was resolved.

Any comments or suggestions regarding this backport would be appreciated.

Thanks,
Diangang

[1]: https://lore.kernel.org/all/2024100959-CVE-2024-47660-2d61@gregkh/

Amir Goldstein (1):
  fsnotify: clear PARENT_WATCHED flags lazily

 fs/notify/fsnotify.c             | 31 +++++++++++++++++++++----------
 fs/notify/fsnotify.h             |  2 +-
 fs/notify/mark.c                 | 32 +++++++++++++++++++++++++++++---
 include/linux/fsnotify_backend.h |  8 +++++---
 4 files changed, 56 insertions(+), 17 deletions(-)

-- 
2.39.5