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
| ||
|
Date: Mon, 30 Jul 2012 10:31:26 -0700 From: Greg Kroah-Hartman <gregkh@...uxfoundation.org> To: linux-kernel@...r.kernel.org, stable@...r.kernel.org Cc: Greg KH <gregkh@...uxfoundation.org>, torvalds@...ux-foundation.org, akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk, Alex Shi <alex.shi@...el.com>, Mel Gorman <mgorman@...e.de>, Minchan Kim <minchan.kim@...il.com>, Pádraig Brady <P@...igBrady.com> Subject: [ 27/41] kswapd: assign new_order and new_classzone_idx after wakeup in sleeping From: Greg KH <gregkh@...uxfoundation.org> 3.0-stable review patch. If anyone has any objections, please let me know. ------------------ From: Alex Shi <alex.shi@...el.com> commit f0dfcde099453aa4c0dc42473828d15a6d492936 upstream. Stable note: Fixes https://bugzilla.redhat.com/show_bug.cgi?id=712019. This patch reduces kswapd CPU usage. There 2 places to read pgdat in kswapd. One is return from a successful balance, another is waked up from kswapd sleeping. The new_order and new_classzone_idx represent the balance input order and classzone_idx. But current new_order and new_classzone_idx are not assigned after kswapd_try_to_sleep(), that will cause a bug in the following scenario. 1: after a successful balance, kswapd goes to sleep, and new_order = 0; new_classzone_idx = __MAX_NR_ZONES - 1; 2: kswapd waked up with order = 3 and classzone_idx = ZONE_NORMAL 3: in the balance_pgdat() running, a new balance wakeup happened with order = 5, and classzone_idx = ZONE_NORMAL 4: the first wakeup(order = 3) finished successufly, return order = 3 but, the new_order is still 0, so, this balancing will be treated as a failed balance. And then the second tighter balancing will be missed. So, to avoid the above problem, the new_order and new_classzone_idx need to be assigned for later successful comparison. Signed-off-by: Alex Shi <alex.shi@...el.com> Acked-by: Mel Gorman <mgorman@...e.de> Reviewed-by: Minchan Kim <minchan.kim@...il.com> Tested-by: Pádraig Brady <P@...igBrady.com> Signed-off-by: Andrew Morton <akpm@...ux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org> Signed-off-by: Mel Gorman <mgorman@...e.de> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org> --- mm/vmscan.c | 2 ++ 1 file changed, 2 insertions(+) --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2908,6 +2908,8 @@ static int kswapd(void *p) balanced_classzone_idx); order = pgdat->kswapd_max_order; classzone_idx = pgdat->classzone_idx; + new_order = order; + new_classzone_idx = classzone_idx; pgdat->kswapd_max_order = 0; pgdat->classzone_idx = pgdat->nr_zones - 1; } -- 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/
Powered by blists - more mailing lists