On Wed, Aug 08, 2012 at 05:48:28PM -0400, Rik van Riel wrote: > Instead of doing a round robin reclaim over all the cgroups in a > zone, we pick the lruvec with the top score and reclaim from that. > > We keep reclaiming from that lruvec until we have reclaimed enough > pages (common for direct reclaim), or that lruvec's score drops in > half. We keep reclaiming from the zone until we have reclaimed enough > pages, or have scanned more than the number of reclaimable pages shifted > by the reclaim priority. > > As an additional change, targeted cgroup reclaim now reclaims from > the highest priority lruvec. This is because when a cgroup hierarchy > hits its limit, the best lruvec to reclaim from may be different than > whatever lruvec is the first we run into iterating from the hierarchy's > "root". > > Signed-off-by: Rik van Riel <riel@xxxxxxxxxx> > --- After fixing the spinlock lockup at patch 03, I started to see kswapd going on an infinite loop around shrink_zone() that dumps the following softlockup report ---8<--- BUG: soft lockup - CPU#0 stuck for 22s! [kswapd0:29] Modules linked in: lockd ip6t_REJECT nf_conntrack_ipv6 nf_conntrack_ipv4 nf_defrag_ipv6 nf_defrag_ipv4 xt_stac irq event stamp: 16668492 hardirqs last enabled at (16668491): [<ffffffff8169d230>] _raw_spin_unlock_irq+0x30/0x50 hardirqs last disabled at (16668492): [<ffffffff816a6e2a>] apic_timer_interrupt+0x6a/0x80 softirqs last enabled at (16668258): [<ffffffff8106db4c>] __do_softirq+0x18c/0x3f0 softirqs last disabled at (16668253): [<ffffffff816a75bc>] call_softirq+0x1c/0x30 CPU 0 Pid: 29, comm: kswapd0 Not tainted 3.6.0-rc1+ #198 Bochs Bochs RIP: 0010:[<ffffffff8111168d>] [<ffffffff8111168d>] rcu_is_cpu_idle+0x2d/0x40 RSP: 0018:ffff880002b99af0 EFLAGS: 00000286 RAX: ffff88003fc0efa0 RBX: 0000000000000001 RCX: 0000000000000000 RDX: ffff880002b98000 RSI: ffffffff81c32420 RDI: 0000000000000246 RBP: ffff880002b99af0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000013 R11: 0000000000000001 R12: 0000000000000013 R13: 0000000000000001 R14: ffffffff8169d630 R15: ffffffff811130ef FS: 0000000000000000(0000) GS:ffff88003fc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 00007fde6b5c2d10 CR3: 0000000001c0b000 CR4: 00000000000006f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process kswapd0 (pid: 29, threadinfo ffff880002b98000, task ffff880002a6a040) Stack: ffff880002b99b80 ffffffff81323fa4 ffff880002a6a6f8 ffff880000000000 ffff880002b99bac 0000000000000000 ffff88003d9d0938 ffff880002a6a040 ffff880002b99b60 0000000000000246 0000000000000000 ffff880002a6a040 Call Trace: [<ffffffff81323fa4>] idr_get_next+0xd4/0x1a0 [<ffffffff810eb727>] css_get_next+0x87/0x1b0 [<ffffffff811b1c56>] mem_cgroup_iter+0x146/0x330 [<ffffffff811b1bfc>] ? mem_cgroup_iter+0xec/0x330 [<ffffffff8116865f>] shrink_zone+0x11f/0x2a0 [<ffffffff8116991b>] kswapd+0x85b/0xf60 [<ffffffff8108e4f0>] ? wake_up_bit+0x40/0x40 [<ffffffff811690c0>] ? zone_reclaim+0x420/0x420 [<ffffffff8108dd8e>] kthread+0xbe/0xd0 [<ffffffff816a74c4>] kernel_thread_helper+0x4/0x10 [<ffffffff8169d630>] ? retint_restore_args+0x13/0x13 [<ffffffff8108dcd0>] ? __init_kthread_worker+0x70/0x70 [<ffffffff816a74c0>] ? gs_change+0x13/0x13 ---8<--- I've applied your suggestion fix (below) on top of this patch and, till now, things are going fine. Will keep you tuned on new developments, though :) ---8<--- diff --git a/mm/vmscan.c b/mm/vmscan.c index 4f6e124..8cb1bbf 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2029,12 +2029,14 @@ restart: score = reclaim_score(memcg, victim, sc); } while (sc->nr_to_reclaim > 0 && score > max_score / 2); + if (!(sc->nr_scanned - nr_scanned)) + return; /* * Do we need to reclaim more pages? * Did we scan fewer pages than the current priority allows? */ if (sc->nr_to_reclaim > 0 && - sc->nr_scanned + nr_scanned < + sc->nr_scanned - nr_scanned < zone_reclaimable_pages(zone) >> sc->priority) goto restart; } -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>