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Date:   Fri, 5 Nov 2021 20:50:04 +0100
To:     Linus Torvalds <torvalds@linux-foundation.org>
Cc:     Qu Wenruo <wqu@suse.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linux-MM <linux-mm@kvack.org>
Subject: Re: Kmap-related crashes and memory leaks on 32bit arch (5.15+)
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crom:   David Sterba <dsterba@suse.cz>
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From:   David Sterba <dsterba@suse.cz>
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On Thu, Nov 04, 2021 at 04:37:25PM -0700, Linus Torvalds wrote:
> On Thu, Nov 4, 2021 at 3:09 PM Linus Torvalds
> <torvalds@linux-foundation.org> wrote:
> > If (a) works, but (b) still fails, then it must be some odd
> > interaction issug withs-----ing else. Which sounds unlikely, since I
> > don't think we really had anything that should affect kmap or anything
> > in this area, but who knows...
> 
> And bisection ends up perhaps somewhat painful, but sounds like the
> way to go if there's no other path forward.

Just to give an update, I tested several merge commits and the btrfs
merge is the first bad (037c50bfbeb33b4c).

Last good is the one right before that,

9c6e8d52a7299  Merge tag 'exfat-for-5.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/linkinjeon/exfat
(plus the fixup to make it compile e66435936756d9bce)

The remaining test to do is the merge conflict resolved by me, as you
suggested.