Commit a7fe942e authored by KAMEZAWA Hiroyuki's avatar KAMEZAWA Hiroyuki Committed by Linus Torvalds

memcg: swapout refcnt fix

css's refcnt is dropped before end of following access.
Hold it until end of access.
Reported-by: default avatarLi Zefan <lizf@cn.fujitsu.com>
Signed-off-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent b85a96c0
......@@ -1171,6 +1171,8 @@ __mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype)
mz = page_cgroup_zoneinfo(pc);
unlock_page_cgroup(pc);
/* at swapout, this memcg will be accessed to record to swap */
if (ctype != MEM_CGROUP_CHARGE_TYPE_SWAPOUT)
css_put(&mem->css);
return mem;
......@@ -1212,6 +1214,8 @@ void mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent)
swap_cgroup_record(ent, memcg);
mem_cgroup_get(memcg);
}
if (memcg)
css_put(&memcg->css);
}
#ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP
......
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