linux-kernel - Re: [BUGFIX][PATCH mmotm] memcg fix swap accounting leak (v3)

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <Pine.LNX.4.64.0812151033060.16370@blonde.anvils>
Date:	Mon, 15 Dec 2008 10:34:26 +0000 (GMT)
From:	Hugh Dickins <hugh@...itas.com>
To:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
cc:	Daisuke Nishimura <nishimura@....nes.nec.co.jp>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"balbir@...ux.vnet.ibm.com" <balbir@...ux.vnet.ibm.com>,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>
Subject: Re: [BUGFIX][PATCH mmotm] memcg fix swap accounting leak (v3)

On Mon, 15 Dec 2008, KAMEZAWA Hiroyuki wrote:
> 
> Fix swapin charge operation of memcg.
> 
> @@ -1139,10 +1139,11 @@ void mem_cgroup_commit_charge_swapin(str
>  	/*
>  	 * Now swap is on-memory. This means this page may be
>  	 * counted both as mem and swap....double count.
> -	 * Fix it by uncharging from memsw. This SwapCache is stable
> -	 * because we're still under lock_page().
> +	 * Fix it by uncharging from memsw. Basically, this SwapCache is stable
> +	 * under lock_page(). But in do_swap_page()::memory.c, reuse_swap_page()
> +	 * may call delete_from_swap_cache() before reach here.
>  	 */
> -	if (do_swap_account) {
> +	if (do_swap_account && PageSwapCache(page)) {
>  		swp_entry_t ent = {.val = page_private(page)};
>  		struct mem_cgroup *memcg;
>  		memcg = swap_cgroup_record(ent, NULL);

Yes, that addition looks good to me.

Hugh
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/