From: Linus Torvalds <torvalds@linux-foundation.org>
To: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-mm <linux-mm@kvack.org>,
the arch/x86 maintainers <x86@kernel.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Michal Hocko <mhocko@kernel.org>
Subject: Re: [mm 4.15-rc8] Random oopses under memory pressure.
Date: Tue, 16 Jan 2018 11:30:54 -0800 [thread overview]
Message-ID: <CA+55aFyThu2FrxUh-4WrGHAd_QX=v1H2L+UNnUkks7n+dSvcfA@mail.gmail.com> (raw)
In-Reply-To: <7f100b0f-3588-be25-41f6-a0e4dde27916@linux.intel.com>
On Tue, Jan 16, 2018 at 12:06 AM, Dave Hansen
<dave.hansen@linux.intel.com> wrote:
> On 01/15/2018 06:14 PM, Linus Torvalds wrote:
>> But I'm adding Dave Hansen explicitly to the cc, in case he has any
>> ideas. Not because I blame him, but he's touched the sparsemem code
>> fairly recently, so maybe he'd have some idea on adding sanity
>> checking to the sparsemem version of pfn_to_page().
>
> I swear I haven't touched it lately!
Heh. I did
git blame -C mm/sparse.c | grep 2017
and your name shows up at the beginning a lot because of commit
c4e1be9ec113 ("mm, sparsemem: break out of loops early").
And Michal Hocko (who shows up even more) was already on the cc.
> I'm not sure I'd go after pfn_to_page(). *Maybe* if we were close to
> the places where we've done a pfn_to_page(), but I'm not seeing those.
Fair enough. I just wanted to add debugging, looked at Tetsuo's
config, and went "no way am I adding debugging to the sparsemem case
because it's so confusing".
That said, I also started looking at "kmap_to_page()". That's
something that is *really* different with HIGHMEM, and while most of
the users are in random drivers that do crazy things, I do note that
one of the users is in mm/swap.c.
That thing goes back to commit 5a178119b0fb ("mm: add support for
direct_IO to highmem pages") and was only used for swap_writepage(),
if I read this right.
That swap_writepage() use of kmap()'ed patches was removed some time
later in commit 62a8067a7f35 ("bio_vec-backed iov_iter"), but the
crazy kmap_to_page() thing remained.
I see nothing actively wrong in there, but it really feels like a
"that is all bogus" thing to me.
> Did anyone else notice the
>
> [ 31.068198] ? vmalloc_sync_all+0x150/0x150
>
> present in a bunch of the stack traces? That should be pretty uncommon.
No, didn't notice that. And yes, vmalloc_sync_all() might be interesting.
> Is it just part of the normal do_page_fault() stack and the stack
> dumper picks up on it?
I don't think so. It should *not* happen normally. The fact that it
shows up in the trace means it happened that time.
It doesn't seem HIGHMEM-related, though. Or maybe the highmem signal
is bogus too, and it's just that Tetsuo's reproducer needs magical
timing.
Linus
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next prev parent reply other threads:[~2018-01-16 19:30 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-05 14:45 [x86? mm? fs? 4.15-rc6] Random oopses by simple write under memory pressure Tetsuo Handa
2018-01-09 10:39 ` [mm? 4.15-rc7] " Tetsuo Handa
2018-01-10 11:49 ` [mm? 4.15-rc7] Random oopses " Tetsuo Handa
2018-01-10 12:45 ` Michal Hocko
2018-01-10 13:37 ` Tetsuo Handa
2018-01-11 13:57 ` Michal Hocko
2018-01-11 14:11 ` Tetsuo Handa
2018-01-11 14:21 ` Michal Hocko
2018-01-11 14:37 ` Tetsuo Handa
2018-01-12 1:31 ` [mm " Tetsuo Handa
2018-01-12 1:42 ` Linus Torvalds
2018-01-12 11:22 ` Tetsuo Handa
2018-01-14 11:54 ` Tetsuo Handa
2018-01-15 23:05 ` Linus Torvalds
2018-01-16 1:15 ` [mm 4.15-rc8] " Tetsuo Handa
2018-01-16 2:14 ` Linus Torvalds
2018-01-16 8:06 ` Dave Hansen
2018-01-16 8:37 ` Ingo Molnar
2018-01-16 19:30 ` Linus Torvalds [this message]
2018-01-16 17:33 ` Tetsuo Handa
2018-01-16 19:34 ` Linus Torvalds
2018-01-17 11:08 ` Tetsuo Handa
2018-01-17 21:39 ` Linus Torvalds
2018-01-17 21:51 ` Linus Torvalds
2018-01-17 22:04 ` Dave Hansen
2018-01-17 22:00 ` Dave Hansen
2018-01-17 22:15 ` Linus Torvalds
2018-01-18 8:12 ` Tetsuo Handa
2018-01-18 12:25 ` Kirill A. Shutemov
2018-01-18 13:12 ` Kirill A. Shutemov
2018-01-18 14:34 ` Kirill A. Shutemov
2018-01-18 14:38 ` Dave Hansen
2018-01-18 14:45 ` Kirill A. Shutemov
2018-01-18 14:51 ` Dave Hansen
2018-01-18 16:58 ` Linus Torvalds
2018-01-18 14:45 ` Dave Hansen
2018-01-18 14:58 ` Andrea Arcangeli
2018-01-18 16:56 ` Kirill A. Shutemov
2018-01-18 17:26 ` Luck, Tony
2018-01-18 17:28 ` Linus Torvalds
2018-01-18 17:26 ` Linus Torvalds
2018-01-18 23:49 ` Kirill A. Shutemov
2018-01-19 12:55 ` Matthew Wilcox
2018-01-19 18:42 ` Linus Torvalds
2018-01-19 22:12 ` Al Viro
2018-01-19 22:53 ` Linus Torvalds
2018-01-20 2:02 ` Al Viro
2018-01-20 5:24 ` Al Viro
2018-01-20 9:38 ` Luc Van Oostenryck
2018-01-18 15:40 ` Kirill A. Shutemov
2018-01-18 17:22 ` Michal Hocko
2018-01-19 10:02 ` Kirill A. Shutemov
2018-01-19 10:33 ` Michal Hocko
2018-01-19 11:49 ` Kirill A. Shutemov
2018-01-19 12:07 ` Michal Hocko
2018-01-19 12:30 ` Kirill A. Shutemov
2018-01-19 2:01 ` Tetsuo Handa
2018-01-11 18:11 ` [mm? 4.15-rc7] " Linus Torvalds
2018-01-11 20:59 ` Tetsuo Handa
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