Re: (resend)WARNING: trying to isolate tail page in isolate_lru_page

[Minchan Kim <minchan@kernel.org>]

On Fri, Aug 26, 2022 at 11:23:10AM -0700, Yang Shi wrote:
> On Fri, Aug 26, 2022 at 9:56 AM Minchan Kim <minchan@kernel.org> wrote:
> >
> > On Fri, Aug 26, 2022 at 11:20:58AM +0800, Yin, Fengwei wrote:
> > >
> > >
> > > On 8/26/2022 2:46 AM, Matthew Wilcox wrote:
> > > >>> Looks like my analysis from yesterday was dropped:
> > > >>>
> > > >>> : This all seems quite plausible.  The reproducer seems to (correct me
> > > >>> : if I'm wrong) create an AF_PACKET socket and mmap it.  af_packet.c
> > > >>> : seems to create compound pages and mmap them.  This isn't folio-related
> > > >>> : at all; I just moved the code that warns about it from mm/vmscan.c to
> > > >>> : folio-compat.c.
> > > >>> :
> > > >>> : Looks like a long-standing bug in MADV_PAGEOUT to me.
> > > >> Such page should never be on lru, right? We could test lru before
> > > >> calling isolate_lru_page() for this case? I know isolate_lru_page()
> > > >> does the check, but the tail page warning is raised before the check.
> > > >>
> > > >> Could the tail page warning be moved under the lru flag test? Seems
> > > >> possible, but it should need extra handling (re-set lru flag). Seems a
> > > >> little bit overkilling.
> > > > There's a number of ways of solving this.  I'm interested in seeing
> > > > which one Minchan thinks is best.
> > > >
> > >
> > > My understanding is:
> > > PageTransCompound() return false for compound page if THP is disabled
> > > in kernel config. Replacing PageTransCompound() with PageCompound()
> > > could work here. But for the long term, folio should be the answer. :).
> >
> > Thanks for reporting and analysis, folks,
> >
> > I agree with Yang since the MADV_PAGEOUT should work with only
> > LRU pages.
> >
> > From 0a43ac31c903bc23299a868a6d6724ff5b807e3d Mon Sep 17 00:00:00 2001
> > From: Minchan Kim <minchan@kernel.org>
> > Date: Fri, 26 Aug 2022 09:37:34 -0700
> > Subject: [PATCH] mm: fix madivse_pageout mishandling on non-LRU page
> > MIME-Version: 1.0
> > Content-Type: text/plain; charset=UTF-8
> > Content-Transfer-Encoding: 8bit
> >
> > MADV_PAGEOUT tries to isolate non-LRU pages and get the warning
> > from isolate_lru_page below.
> > Fix it with checking PageLRU in advance.
> >
> > ------------[ cut here ]------------
> > trying to isolate tail page
> > WARNING: CPU: 0 PID: 6175 at mm/folio-compat.c:158 isolate_lru_page+0x130/0x140
> > Modules linked in:
> > CPU: 0 PID: 6175 Comm: syz-executor.0 Not tainted 5.18.12 #1
> > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014
> > RIP: 0010:isolate_lru_page+0x130/0x140
> >
> > Link: https://lore.kernel.org/linux-mm/485f8c33.2471b.182d5726afb.Coremail.hantianshuo@iie.ac.cn/
> > Reported-by: 韩天硕 <hantianshuo@iie.ac.cn>
> > Suggested-by: Yang Shi <shy828301@gmail.com>
> > Fixes: 1a4e58cce84e ("mm: introduce MADV_PAGEOUT")
> > Cc: stable@vger.kernel.org
> > Signed-off-by: Minchan Kim <minchan@kernel.org>
> 
> Thanks for the patch, looks good to me. Will you post it to the
> mailing list? Anyway you could have my ack.

IIRC, Andrew usually has picked up the patch in the thread.
If he don't within a few days, let me post the new one 

Thanks!