On Wed 12-08-20 11:25:53, Alex Shi wrote: > >From 999b0fe5fc65865c3b59ff28500d45572a4a9570 Mon Sep 17 00:00:00 2001 > From: Alex Shi <alex.shi@xxxxxxxxxxxxxxxxx> > Date: Wed, 5 Aug 2020 21:02:30 +0800 > Subject: [PATCH 2/6] mm/memcg: bail out early from swap accounting when memcg > is disabled > > 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. > > ---[ end trace f1f34bfc3b32ed2f ]--- > 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) Yes this is better. It would be even more informative if you added the backtrace. > Signed-off-by: Alex Shi <alex.shi@xxxxxxxxxxxxxxxxx> > Reviewed-by: Roman Gushchin <guro@xxxxxx> > Acked-by: Michal Hocko <mhocko@xxxxxxxx> > 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 > --- > mm/memcontrol.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 299382fc55a9..419cf565f40b 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -7098,6 +7098,9 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t entry) > VM_BUG_ON_PAGE(PageLRU(page), page); > VM_BUG_ON_PAGE(page_count(page), page); > > + if (mem_cgroup_disabled()) > + return; > + > if (cgroup_subsys_on_dfl(memory_cgrp_subsys)) > return; > > @@ -7163,6 +7166,9 @@ int mem_cgroup_try_charge_swap(struct page *page, swp_entry_t entry) > struct mem_cgroup *memcg; > unsigned short oldid; > > + if (mem_cgroup_disabled()) > + return 0; > + > if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) > return 0; > > -- > 1.8.3.1 -- Michal Hocko SUSE Labs
