From a54d53bfda519722bd3b4990422865e5bc5fe8cd Mon Sep 17 00:00:00 2001 From: Johannes Weiner Date: Fri, 30 Jun 2017 11:01:06 +1000 Subject: [PATCH] mm-memcontrol-per-lruvec-stats-infrastructure-fix Fix the following crash in the new cgroup stat keeping code: Freeing unused kernel memory: 856K Write protecting the kernel read-only data: 8192k Freeing unused kernel memory: 1104K Freeing unused kernel memory: 588K page:ffffea000005d8c0 count:2 mapcount:1 mapping: (null) index:0x0 flags: 0x800000000000801(locked|reserved) raw: 0800000000000801 0000000000000000 0000000000000000 0000000200000000 raw: ffffea000005d8e0 ffffea000005d8e0 0000000000000000 0000000000000000 page dumped because: not cgrouped, will crash BUG: unable to handle kernel NULL pointer dereference at 00000000000004d8 IP: page_add_file_rmap+0x56/0xf0 PGD 0 P4D 0 Oops: 0000 [#1] SMP CPU: 0 PID: 1 Comm: init Not tainted 4.12.0-rc2-00065-g390160f076be-dirty #326 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-20170228_101828-anatol 04/01/2014 task: ffff88007d380000 task.stack: ffffc9000031c000 RIP: 0010:page_add_file_rmap+0x56/0xf0 RSP: 0000:ffffc9000031fd88 EFLAGS: 00010202 RAX: 0000000000000000 RBX: ffffea000005d8c0 RCX: 0000000000000006 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88007ffde000 RBP: ffffc9000031fd98 R08: 0000000000000003 R09: 0000000000000000 R10: ffffc9000031fd18 R11: 0000000000000000 R12: ffff88007ffdfab8 R13: ffffea000005d8c0 R14: ffff88007c76d508 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff88007fc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000000004d8 CR3: 000000007c76c000 CR4: 00000000000006b0 Call Trace: alloc_set_pte+0xb5/0x2f0 finish_fault+0x2b/0x50 __handle_mm_fault+0x3e5/0xb90 handle_mm_fault+0x284/0x340 __do_page_fault+0x1fb/0x410 do_page_fault+0xc/0x10 page_fault+0x22/0x30 This is a special page being faulted, and these will never be charged to a cgroup. Assume the root cgroup for uncharged pages to fix this. Link: http://lkml.kernel.org/r/20170531171450.GA10481@cmpxchg.org Signed-off-by: Johannes Weiner Cc: Josef Bacik Cc: Michal Hocko Cc: Vladimir Davydov Cc: Rik van Riel Cc: Tony Lindgren Cc: Russell King Cc: Yury Norov Cc: Stephen Rothwell Signed-off-by: Andrew Morton --- include/linux/memcontrol.h | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 6901a61c499e99..c77ce0ff211c16 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -596,18 +596,26 @@ static inline void mod_lruvec_state(struct lruvec *lruvec, static inline void __mod_lruvec_page_state(struct page *page, enum node_stat_item idx, int val) { + struct mem_cgroup *memcg; struct lruvec *lruvec; - lruvec = mem_cgroup_lruvec(page_pgdat(page), page->mem_cgroup); + /* Special pages in the VM aren't charged, use root */ + memcg = page->mem_cgroup ? : root_mem_cgroup; + + lruvec = mem_cgroup_lruvec(page_pgdat(page), memcg); __mod_lruvec_state(lruvec, idx, val); } static inline void mod_lruvec_page_state(struct page *page, enum node_stat_item idx, int val) { + struct mem_cgroup *memcg; struct lruvec *lruvec; - lruvec = mem_cgroup_lruvec(page_pgdat(page), page->mem_cgroup); + /* Special pages in the VM aren't charged, use root */ + memcg = page->mem_cgroup ? : root_mem_cgroup; + + lruvec = mem_cgroup_lruvec(page_pgdat(page), memcg); mod_lruvec_state(lruvec, idx, val); }