linux-kernel - Re: Regression in next with ext4 oops

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Message-ID: <87fuobq4v1.fsf@kamboji.qca.qualcomm.com>
Date:   Tue, 04 Oct 2016 22:41:22 +0300
From:   Kalle Valo <kvalo@...eaurora.org>
To:     Tony Lindgren <tony@...mide.com>
Cc:     Al Viro <viro@...IV.linux.org.uk>, Theodore Ts'o <tytso@....edu>,
        Jan Kara <jack@...e.cz>, Eric Biggers <ebiggers@...gle.com>,
        Andreas Dilger <adilger@...ger.ca>,
        Jaegeuk Kim <jaegeuk@...nel.org>, linux-ext4@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-omap@...r.kernel.org
Subject: Re: Regression in next with ext4 oops

Tony Lindgren <tony@...mide.com> writes:

> * Tony Lindgren <tony@...mide.com> [161004 12:17]:
>> Hi,
>> 
>> * Al Viro <viro@...IV.linux.org.uk> [161004 08:00]:
>> > On Tue, Oct 04, 2016 at 10:02:31AM -0400, Theodore Ts'o wrote:
>> > > On Tue, Oct 04, 2016 at 11:00:41AM +0200, Jan Kara wrote:
>> > > > Never seen this but I suspect it is a fallout from Al's directory locking
>> > > > changes. In particular ext4_htree_fill_tree() builds rb-tree of found
>> > > > directory entries in file->private_data (and generally modifies the
>> > > > structure stored there) but after Al's changes we don't have exclusive
>> > > > access to struct file if I'm right so if two processes end up calling
>> > > > getdents() for the same 'struct file' we are doomed.
>> > > 
>> > > I haven't seen it either, and I've been doing a lot of testing on the
>> > > ext4 test branch.  So I'm guessing Tony has the only reliable repro
>> > > for the problem at the moment.  That being said, it shouldn't be that
>> > > hard to create a test case for this and add it to xfstests.
>> > > 
>> > > I'm pretty sure Jan is right about this, though, but it would be great
>> > > to a get a quick confirmation from Tony if at all possible.
>> > 
>> > Jan is wrong - we do have per-struct-file serialization for getdents()
>> > et.al.  It might be a race between getdents() on *different* struct
>> > file for the same directory, but ->private_data is not a problem.
>> 
>> OK found the guilty person after git bisect and that's me.
>> 
>> Git bisect points to commit d776fc86b82f ("wlcore: sdio: Populate config
>> firmware data"), so adding Kalle to Cc.
>> 
>> Looks like update-initramfs does rmmod of wlcore_sdio and that triggers
>> some issue with the wlcore driver or with SDIO/MMC. Or maybe it's a memory
>> corruption issue. I don't know yet exactly what's going on here yet but
>> I plan to find out after some lunch.
>
> And the patch below seems to fix the issue as the driver is now
> using devm_kzalloc. Will do some more testing and then will post
> a proper patch. The same issue might be there for SPI glue also.

This was already posted and you even acked it :)

wlcore: sdio: drop kfree for memory allocated with devm_kzalloc

https://patchwork.kernel.org/patch/9353985/

-- 
Kalle Valo