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@xxxxxxxxxx> 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@xxxxxxxxxx> > > 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@xxxxxxxxx/ > > Reported-by: 韩天硕 <hantianshuo@xxxxxxxxx> > > Suggested-by: Yang Shi <shy828301@xxxxxxxxx> > > Fixes: 1a4e58cce84e ("mm: introduce MADV_PAGEOUT") > > Cc: stable@xxxxxxxxxxxxxxx > > Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx> > > 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!
