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From: Kent Overstreet <kent.overstreet@gmail.com>
To: Eric Wheeler <bcachefs@lists.ewheeler.net>
Cc: linux-bcachefs@vger.kernel.org
Subject: Re: bcachefs: Kernel panic - not syncing: trans path oveflow
Date: Wed, 9 Mar 2022 20:49:03 -0500	[thread overview]
Message-ID: <YilZD2oxhUtFVCfu@moria.home.lan> (raw)
In-Reply-To: <6bc8aca6-2f93-4a81-376-13155fcc5d7@ewheeler.net>

On Wed, Mar 09, 2022 at 01:14:58PM -0800, Eric Wheeler wrote:
> Hi Kent,
> 
> We just started testing bcachefs snapshots this week: we have a bunch of 
> mysql replicas, each in its own subvolume.  Every 4 hours we stop mysql, 
> run a subvolume snapshot and restart mysql, so it gets lots of snapshot 
> and sync IO from the many database instances.

Cool! Would love to hear any comments you've got so far.

> We hit the following bcachefs panic while testing commit# 
> 5490c9c529770aa18b2571bd98f5416ed9ae24c6 from March 3rd. Can you tell what 
> the issue might be?
> 
> It is easily reproducable, the same problem hits shortly after we reboot 
> and remount so happy to test patches or git-pull's to rebuild with:
> 
> Here is the stack trace (more logs below):

So it looks like there's some code that iterates over btree keys and goes
further than it's supposed to - we have paths that point to different inode
numbers and that's not supposed to happen in the write path, we're only updating
a single inode.

I've had a report of a similar bug in the data move path, which may or may not
be the same as this bug - but I haven't worked up a repro for it yet so I
haven't figured out yet which code path is allocating these btree paths. Could
you enable CONFIG_BCACHEFS_DEBUG, then run your log through
scripts/decode_stacktrace.sh from the kernel source tree?

  reply	other threads:[~2022-03-10  1:49 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-03-09 21:14 bcachefs: Kernel panic - not syncing: trans path oveflow Eric Wheeler
2022-03-10  1:49 ` Kent Overstreet [this message]
2022-03-10 22:25   ` Eric Wheeler
2022-03-11  0:43     ` Kent Overstreet
2022-03-11 18:56     ` Kent Overstreet
2022-03-11 20:22       ` Eric Wheeler

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