Bug#1144613: linux-image-7.1.6+deb14-amd64: ext4 st_mtime and time() inconsistency

From	Salvatore Bonaccorso <carnil@debian.org>
Newsgroups	linux.debian.bugs.dist, linux.debian.kernel
Subject	Bug#1144613: linux-image-7.1.6+deb14-amd64: ext4 st_mtime and time() inconsistency
Date	2026-08-19 16:00 +0200
Message-ID	<NtOZH-bTCD-1@gated-at.bofh.it> (permalink)
References	(1 earlier) <NtN7z-bSDS-1@gated-at.bofh.it> <NsTI5-bnRg-1@gated-at.bofh.it> <NtNAB-bSXq-3@gated-at.bofh.it> <NsTI5-bnRg-1@gated-at.bofh.it> <NtNAB-bSXq-3@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Cross-posted to 2 groups.

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Hi,

On Wed, Aug 19, 2026 at 02:28:51PM +0200, Vincent Lefevre wrote:
> Control: retitle -1 linux-image-7.1.6+deb14-amd64: st_mtime and time() inconsistency
> 
> On 2026-08-19 13:48:48 +0200, Vincent Lefevre wrote:
> > Here's a simple program to reproduce the issue. On my machine,
> > a difference is output many times every second (apparently,
> > when the clock is very close to an integer number of seconds).
> [...]
> 
> This also occurs in /dev/shm (tmpfs).
> 
> And I cannot reproduce this issue under Debian 13 (trixie) with
> the 6.12.96+deb13-amd64 kernel.

I think this is a consequence of 4e40eff0b5737c ("fs: add
infrastructure for multigrain timestamps") and following in 6.13-rc1.

time(2) has only an accurancy in second, so the code might need to
use clock_gettime(2).

Regards,
Salvatore

Thread

Bug#1144613: linux-image-7.1.6+deb14-amd64: ext4 st_mtime and time() inconsistency Vincent Lefevre <vincent@vinc17.net> - 2026-08-19 14:00 +0200
  Bug#1144613: linux-image-7.1.6+deb14-amd64: ext4 st_mtime and time() inconsistency Vincent Lefevre <vincent@vinc17.net> - 2026-08-19 14:30 +0200
    Processed: Re: linux-image-7.1.6+deb14-amd64: ext4 st_mtime and  time() inconsistency "Debian Bug Tracking System" <owner@bugs.debian.org> - 2026-08-19 14:30 +0200
    Bug#1144613: linux-image-7.1.6+deb14-amd64: ext4 st_mtime and time() inconsistency Salvatore Bonaccorso <carnil@debian.org> - 2026-08-19 16:00 +0200
      Bug#1144613: linux-image-7.1.6+deb14-amd64: ext4 st_mtime and time() inconsistency Vincent Lefevre <vincent@vinc17.net> - 2026-08-19 16:30 +0200
        Bug#1144613: linux-image-7.1.6+deb14-amd64: ext4 st_mtime and time() inconsistency Vincent Lefevre <vincent@vinc17.net> - 2026-08-19 17:20 +0200
          Bug#1144613: linux-image-7.1.6+deb14-amd64: ext4 st_mtime and time() inconsistency Vincent Lefevre <vincent@vinc17.net> - 2026-08-19 19:20 +0200

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