linux-kernel - Re: [git pull] d

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Message-ID: <Z5gWQnUDMyE5sniC@lappy>
Date: Mon, 27 Jan 2025 18:26:58 -0500
From: Sasha Levin <sashal@...nel.org>
To: Al Viro <viro@...iv.linux.org.uk>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [git pull] d_revalidate pile

On Mon, Jan 27, 2025 at 10:40:59PM +0000, Al Viro wrote:
>On Mon, Jan 27, 2025 at 09:34:56PM +0000, Al Viro wrote:
>
>> If so, then
>> 	a) it's a false positive (and IIRC, it's not the first time
>> kfence gets confused by that)
>> 	b) your bisection will probably converge to bdd9951f60f9
>> "dissolve external_name.u into separate members" which is where we'd
>> ended up with offsetof(struct external_name, name) being 4 modulo 8.
>>
>> As a quick test, try to flip the order of head and count in
>> struct external_name and see if that makes the warning go away.
>> If it does, I'm pretty certain that theory above is correct.
>
>Not quite...   dentry_string_cmp() assumes that ->d_name.name is
>word-aligned, so load_unaligned_zeropad() is done only to the
>second string (the one we compare against).

Sorry for the silence on my end: this issue doesn't reproduce
consistently, so I need to do more runs for these tests.

-- 
Thanks,
Sasha