On Thu, Oct 29, 2020 at 06:44:47PM +0800, Alex Shi wrote: > If we disabled memcg by cgroup_disable=memory, page->memcg will be NULL > and so the charge is skipped and that will trigger a warning like below. > Let's return from the funcs earlier. > > anon flags:0x5005b48008000d(locked|uptodate|dirty|swapbacked) > raw: 005005b48008000d dead000000000100 dead000000000122 ffff8897c7c76ad1 > raw: 0000000000000022 0000000000000000 0000000200000000 0000000000000000 > page dumped because: VM_WARN_ON_ONCE_PAGE(!memcg) > ... > RIP: 0010:vprintk_emit+0x1f7/0x260 > Code: 00 84 d2 74 72 0f b6 15 27 58 64 01 48 c7 c0 00 d4 72 82 84 d2 74 09 f3 90 0f b6 10 84 d2 75 f7 e8 de 0d 00 00 4c 89 e7 57 9d <0f> 1f 44 00 00 e9 62 ff ff ff 80 3d 88 c9 3a 01 00 0f 85 54 fe ff > RSP: 0018:ffffc9000faab358 EFLAGS: 00000202 > RAX: ffffffff8272d400 RBX: 000000000000005e RCX: ffff88afd80d0040 > RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000000000202 > RBP: ffffc9000faab3a8 R08: ffffffff8272d440 R09: 0000000000022480 > R10: 00120c77be68bfac R11: 0000000000cd7568 R12: 0000000000000202 > R13: 0057ffffc0080005 R14: ffffffff820a0130 R15: ffffc9000faab3e8 > ? vprintk_emit+0x140/0x260 > vprintk_default+0x1a/0x20 > vprintk_func+0x4f/0xc4 > ? vprintk_func+0x4f/0xc4 > printk+0x53/0x6a > ? xas_load+0xc/0x80 > __dump_page.cold.6+0xff/0x4ee > ? xas_init_marks+0x23/0x50 > ? xas_store+0x30/0x40 > ? free_swap_slot+0x43/0xd0 > ? put_swap_page+0x119/0x320 > ? update_load_avg+0x82/0x580 > dump_page+0x9/0xb > mem_cgroup_try_charge_swap+0x16e/0x1d0 > get_swap_page+0x130/0x210 > add_to_swap+0x41/0xc0 > shrink_page_list+0x99e/0xdf0 > shrink_inactive_list+0x199/0x360 > shrink_lruvec+0x40d/0x650 > ? _cond_resched+0x14/0x30 > ? _cond_resched+0x14/0x30 > shrink_node+0x226/0x6e0 > do_try_to_free_pages+0xd0/0x400 > try_to_free_pages+0xef/0x130 > __alloc_pages_slowpath.constprop.127+0x38d/0xbd0 > ? ___slab_alloc+0x31d/0x6f0 > __alloc_pages_nodemask+0x27f/0x2c0 > alloc_pages_vma+0x75/0x220 > shmem_alloc_page+0x46/0x90 > ? release_pages+0x1ae/0x410 > shmem_alloc_and_acct_page+0x77/0x1c0 > shmem_getpage_gfp+0x162/0x910 > shmem_fault+0x74/0x210 > ? filemap_map_pages+0x29c/0x410 > __do_fault+0x37/0x190 > handle_mm_fault+0x120a/0x1770 > exc_page_fault+0x251/0x450 > ? asm_exc_page_fault+0x8/0x30 > asm_exc_page_fault+0x1e/0x30 > > Signed-off-by: Alex Shi <alex.shi@xxxxxxxxxxxxxxxxx> > Reviewed-by: Roman Gushchin <guro@xxxxxx> > Acked-by: Michal Hocko <mhocko@xxxxxxxx> > Acked-by: Hugh Dickins <hughd@xxxxxxxxxx> > Cc: Johannes Weiner <hannes@xxxxxxxxxxx> > Cc: Michal Hocko <mhocko@xxxxxxxxxx> > Cc: Vladimir Davydov <vdavydov.dev@xxxxxxxxx> > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > Cc: cgroups@xxxxxxxxxxxxxxx > Cc: linux-mm@xxxxxxxxx > Cc: linux-kernel@xxxxxxxxxxxxxxx Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx> This should go in before the previous patch that adds the WARN for it.
