linux-ext4 - Re: [GIT PULL] ext2, quota, and udf fixes for 6.6-rc1

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Date:   Thu, 19 Oct 2023 21:10:25 +0300
From:   Andy Shevchenko <andriy.shevchenko@...el.com>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Josh Poimboeuf <jpoimboe@...nel.org>, Jan Kara <jack@...e.cz>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Kees Cook <keescook@...omium.org>,
        Ferry Toth <ftoth@...londelft.nl>,
        linux-fsdevel@...r.kernel.org, linux-ext4@...r.kernel.org
Subject: Re: [GIT PULL] ext2, quota, and udf fixes for 6.6-rc1

On Thu, Oct 19, 2023 at 10:51:18AM -0700, Linus Torvalds wrote:
> On Thu, 19 Oct 2023 at 10:26, Linus Torvalds
> <torvalds@...ux-foundation.org> wrote:
> >
> > That said, the quota dependency is quite odd, since normally I
> > wouldn't expect the quota code to really even trigger much during
> > boot. When it triggers that consistently, and that early during boot,
> > I would expect others to have reported more of this.
> >
> > Strange.
> 
> Hmm. I do think the quota list handling has some odd things going on.
> And it did change with the whole ->dq_free thing.
> 
> Some of it is just bad:
> 
>   #ifdef CONFIG_QUOTA_DEBUG
>           /* sanity check */
>           BUG_ON(!list_empty(&dquot->dq_free));
>   #endif
> 
> is done under a spinlock, and if it ever triggers, the machine is
> dead. Dammit, I *hate* how people use BUG_ON() for assertions. It's a
> disgrace. That should be a WARN_ON_ONCE().

In my configuration

CONFIG_QUOTA=y
CONFIG_QUOTA_NETLINK_INTERFACE=y
# CONFIG_QUOTA_DEBUG is not set
CONFIG_QUOTA_TREE=y
# CONFIG_QFMT_V1 is not set
CONFIG_QFMT_V2=y
CONFIG_QUOTACTL=y

> And it does have quite a bit of list-related changes, with the whole
> series from Baokun Li changing how the ->dq_free list works.
> 
> The fact that it consistently bisects to the merge is still odd.

Exactly! Imre suggested to test the merge point itself, so
far I tested the result of the merge in the upstream, but not
the branch/tag that has been merged.

Let's see if I have time this week for that. This hunting is a bit exhaustive.

-- 
With Best Regards,
Andy Shevchenko