On Tue, May 28, 2019 at 05:14:07PM +0200, Michal Hocko wrote: > [Cc Pankaj Suryawanshi who has reported a similar problem > http://lkml.kernel.org/r/SG2PR02MB309806967AE91179CAFEC34BE84B0@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx] > > On Fri 24-05-19 16:11:14, Minchan Kim wrote: > > There was below bugreport from Wu Fangsuo. > > > > 7200 [ 680.491097] c4 7125 (syz-executor) page:ffffffbf02f33b40 count:86 mapcount:84 mapping:ffffffc08fa7a810 index:0x24 > > 7201 [ 680.531186] c4 7125 (syz-executor) flags: 0x19040c(referenced|uptodate|arch_1|mappedtodisk|unevictable|mlocked) > > 7202 [ 680.544987] c0 7125 (syz-executor) raw: 000000000019040c ffffffc08fa7a810 0000000000000024 0000005600000053 > > 7203 [ 680.556162] c0 7125 (syz-executor) raw: ffffffc009b05b20 ffffffc009b05b20 0000000000000000 ffffffc09bf3ee80 > > 7204 [ 680.566860] c0 7125 (syz-executor) page dumped because: VM_BUG_ON_PAGE(PageLRU(page) || PageUnevictable(page)) > > 7205 [ 680.578038] c0 7125 (syz-executor) page->mem_cgroup:ffffffc09bf3ee80 > > 7206 [ 680.585467] c0 7125 (syz-executor) ------------[ cut here ]------------ > > 7207 [ 680.592466] c0 7125 (syz-executor) kernel BUG at /home/build/farmland/adroid9.0/kernel/linux/mm/vmscan.c:1350! > > 7223 [ 680.603663] c0 7125 (syz-executor) Internal error: Oops - BUG: 0 [#1] PREEMPT SMP > > 7224 [ 680.611436] c0 7125 (syz-executor) Modules linked in: > > 7225 [ 680.616769] c0 7125 (syz-executor) CPU: 0 PID: 7125 Comm: syz-executor Tainted: G S 4.14.81 #3 > > 7226 [ 680.626826] c0 7125 (syz-executor) Hardware name: ASR AQUILAC EVB (DT) > > 7227 [ 680.633623] c0 7125 (syz-executor) task: ffffffc00a54cd00 task.stack: ffffffc009b00000 > > 7228 [ 680.641917] c0 7125 (syz-executor) PC is at shrink_page_list+0x1998/0x3240 > > 7229 [ 680.649144] c0 7125 (syz-executor) LR is at shrink_page_list+0x1998/0x3240 > > 7230 [ 680.656303] c0 7125 (syz-executor) pc : [<ffffff90083a2158>] lr : [<ffffff90083a2158>] pstate: 60400045 > > 7231 [ 680.666086] c0 7125 (syz-executor) sp : ffffffc009b05940 > > .. > > 7342 [ 681.671308] c0 7125 (syz-executor) [<ffffff90083a2158>] shrink_page_list+0x1998/0x3240 > > 7343 [ 681.679567] c0 7125 (syz-executor) [<ffffff90083a3dc0>] reclaim_clean_pages_from_list+0x3c0/0x4f0 > > 7344 [ 681.688793] c0 7125 (syz-executor) [<ffffff900837ed64>] alloc_contig_range+0x3bc/0x650 > > 7347 [ 681.717421] c0 7125 (syz-executor) [<ffffff90084925cc>] cma_alloc+0x214/0x668 > > 7348 [ 681.724892] c0 7125 (syz-executor) [<ffffff90091e4d78>] ion_cma_allocate+0x98/0x1d8 > > 7349 [ 681.732872] c0 7125 (syz-executor) [<ffffff90091e0b20>] ion_alloc+0x200/0x7e0 > > 7350 [ 681.740302] c0 7125 (syz-executor) [<ffffff90091e154c>] ion_ioctl+0x18c/0x378 > > 7351 [ 681.747738] c0 7125 (syz-executor) [<ffffff90084c6824>] do_vfs_ioctl+0x17c/0x1780 > > 7352 [ 681.755514] c0 7125 (syz-executor) [<ffffff90084c7ed4>] SyS_ioctl+0xac/0xc0 > > > > Wu found it's due to [1]. Before that, unevictable page goes to cull_mlocked > > routine so that it couldn't reach the VM_BUG_ON_PAGE line. > > > > To fix the issue, this patch filter out unevictable LRU pages > > from the reclaim_clean_pages_from_list in CMA. > > The changelog is rather modest on details and I have to confess I have > little bit hard time to understand it. E.g. why do not we need to handle > the regular reclaim path? No need to pass unevictable pages into regular reclaim patch if we are able to know in advance. > > > [1] ad6b67041a45, mm: remove SWAP_MLOCK in ttu > > > > Cc: <stable@xxxxxxxxxx> [4.12+] > > Reported-debugged-by: Wu Fangsuo <fangsuowu@xxxxxxxxxxxx> > > Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx> > > --- > > mm/vmscan.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/mm/vmscan.c b/mm/vmscan.c > > index d9c3e873eca6..7350afae5c3c 100644 > > --- a/mm/vmscan.c > > +++ b/mm/vmscan.c > > @@ -1505,7 +1505,7 @@ unsigned long reclaim_clean_pages_from_list(struct zone *zone, > > > > list_for_each_entry_safe(page, next, page_list, lru) { > > if (page_is_file_cache(page) && !PageDirty(page) && > > - !__PageMovable(page)) { > > + !__PageMovable(page) && !PageUnevictable(page)) { > > ClearPageActive(page); > > list_move(&page->lru, &clean_pages); > > } > > -- > > 2.22.0.rc1.257.g3120a18244-goog > > > > -- > Michal Hocko > SUSE Labs
