From: Sasha Levin <sasha.levin@oracle.com>
To: Ingo Molnar <mingo@kernel.org>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Paul Turner <pjt@google.com>,
Lee Schermerhorn <Lee.Schermerhorn@hp.com>,
Christoph Lameter <cl@linux.com>, Rik van Riel <riel@redhat.com>,
Mel Gorman <mgorman@suse.de>,
Andrew Morton <akpm@linux-foundation.org>,
Andrea Arcangeli <aarcange@redhat.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
Johannes Weiner <hannes@cmpxchg.org>,
Hugh Dickins <hughd@google.com>, Dave Jones <davej@redhat.com>
Subject: Re: [PATCH 19/33] sched: Add adaptive NUMA affinity support
Date: Mon, 26 Nov 2012 15:32:13 -0500 [thread overview]
Message-ID: <50B3D1CD.10802@oracle.com> (raw)
In-Reply-To: <1353624594-1118-20-git-send-email-mingo@kernel.org>
Hi all,
On 11/22/2012 05:49 PM, Ingo Molnar wrote:
> +static void task_numa_placement(struct task_struct *p)
> +{
> + int seq = ACCESS_ONCE(p->mm->numa_scan_seq);
I was fuzzing with trinity on my fake numa setup, and discovered that this can
be called for task_structs with p->mm == NULL, which would cause things like:
[ 1140.001957] BUG: unable to handle kernel NULL pointer dereference at 00000000000006d0
[ 1140.010037] IP: [<ffffffff81157627>] task_numa_placement+0x27/0x1a0
[ 1140.015020] PGD 9b002067 PUD 9fb3c067 PMD 14a89067 PTE 5a4098bf040
[ 1140.015020] Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
[ 1140.015020] Dumping ftrace buffer:
[ 1140.015020] (ftrace buffer empty)
[ 1140.015020] CPU 1
[ 1140.015020] Pid: 3179, comm: ksmd Tainted: G W 3.7.0-rc6-next-20121126-sasha-00015-gb04382b-dirty #200
[ 1140.015020] RIP: 0010:[<ffffffff81157627>] [<ffffffff81157627>] task_numa_placement+0x27/0x1a0
[ 1140.015020] RSP: 0018:ffff8800bfae5b08 EFLAGS: 00010292
[ 1140.015020] RAX: 0000000000000000 RBX: ffff8800bfaeb000 RCX: 0000000000000001
[ 1140.015020] RDX: ffff880007c00000 RSI: 000000000000000e RDI: ffff8800bfaeb000
[ 1140.015020] RBP: ffff8800bfae5b38 R08: ffff8800bf805e00 R09: ffff880000369000
[ 1140.015020] R10: 0000000000000000 R11: 0000000000000000 R12: 000000000000000e
[ 1140.015020] R13: 0000000000000004 R14: 0000000000000001 R15: 0000000000000064
[ 1140.015020] FS: 0000000000000000(0000) GS:ffff880007c00000(0000) knlGS:0000000000000000
[ 1140.015020] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 1140.015020] CR2: 00000000000006d0 CR3: 0000000097b18000 CR4: 00000000000406e0
[ 1140.015020] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 1140.015020] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
[ 1140.015020] Process ksmd (pid: 3179, threadinfo ffff8800bfae4000, task ffff8800bfaeb000)
[ 1140.015020] Stack:
[ 1140.015020] 0000000000000000 0000000000000000 000000000000000e ffff8800bfaeb000
[ 1140.015020] 000000000000000e 0000000000000004 ffff8800bfae5b88 ffffffff8115a577
[ 1140.015020] ffff8800bfae5b68 ffffffff00000001 ffff88000c1d0068 ffffea0000ec1000
[ 1140.015020] Call Trace:
[ 1140.015020] [<ffffffff8115a577>] task_numa_fault+0xb7/0xd0
[ 1140.015020] [<ffffffff81230d96>] do_numa_page.isra.42+0x1b6/0x270
[ 1140.015020] [<ffffffff8126fe08>] ? mem_cgroup_count_vm_event+0x178/0x1a0
[ 1140.015020] [<ffffffff812333f4>] handle_pte_fault+0x174/0x220
[ 1140.015020] [<ffffffff819e7ad9>] ? __const_udelay+0x29/0x30
[ 1140.015020] [<ffffffff81234780>] handle_mm_fault+0x320/0x350
[ 1140.015020] [<ffffffff81256845>] break_ksm+0x65/0xc0
[ 1140.015020] [<ffffffff81256b4d>] break_cow+0x5d/0x80
[ 1140.015020] [<ffffffff81258442>] cmp_and_merge_page+0x122/0x1e0
[ 1140.015020] [<ffffffff81258565>] ksm_do_scan+0x65/0xa0
[ 1140.015020] [<ffffffff8125860f>] ksm_scan_thread+0x6f/0x2d0
[ 1140.015020] [<ffffffff8113b990>] ? abort_exclusive_wait+0xb0/0xb0
[ 1140.015020] [<ffffffff812585a0>] ? ksm_do_scan+0xa0/0xa0
[ 1140.015020] [<ffffffff8113a723>] kthread+0xe3/0xf0
[ 1140.015020] [<ffffffff8113a640>] ? __kthread_bind+0x40/0x40
[ 1140.015020] [<ffffffff83c8813c>] ret_from_fork+0x7c/0xb0
[ 1140.015020] [<ffffffff8113a640>] ? __kthread_bind+0x40/0x40
[ 1140.015020] Code: 00 00 00 00 55 48 89 e5 41 55 41 54 53 48 89 fb 48 83 ec 18 48 c7 45 d0 00 00 00 00 48 8b 87 a0 04 00 00 48
c7 45 d8 00 00 00 00 <8b> 80 d0 06 00 00 39 87 d4 15 00 00 0f 84 57 01 00 00 89 87 d4
[ 1140.015020] RIP [<ffffffff81157627>] task_numa_placement+0x27/0x1a0
[ 1140.015020] RSP <ffff8800bfae5b08>
[ 1140.015020] CR2: 00000000000006d0
[ 1140.660568] ---[ end trace 9f1fd31243556513 ]---
In exchange to this bug report, I have couple of questions about this NUMA code which I wasn't
able to answer myself :)
- In this case, would it mean that KSM may run on one node, but scan the memory of a different node?
- If yes, we should migrate KSM to each node we scan, right? Or possibly start a dedicated KSM
thread for each NUMA node?
- Is there a class of per-numa threads in the works?
Thanks,
Sasha
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next prev parent reply other threads:[~2012-11-26 20:33 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-22 22:49 [PATCH 00/33] Latest numa/core release, v17 Ingo Molnar
2012-11-22 22:49 ` [PATCH 01/33] mm/generic: Only flush the local TLB in ptep_set_access_flags() Ingo Molnar
2012-11-22 22:49 ` [PATCH 02/33] x86/mm: Only do a local tlb flush " Ingo Molnar
2012-11-22 22:49 ` [PATCH 03/33] x86/mm: Introduce pte_accessible() Ingo Molnar
2012-11-22 22:49 ` [PATCH 04/33] mm: Only flush the TLB when clearing an accessible pte Ingo Molnar
2012-11-22 22:49 ` [PATCH 05/33] x86/mm: Completely drop the TLB flush from ptep_set_access_flags() Ingo Molnar
2012-11-22 22:49 ` [PATCH 06/33] mm: Count the number of pages affected in change_protection() Ingo Molnar
2012-11-22 22:49 ` [PATCH 07/33] mm: Optimize the TLB flush of sys_mprotect() and change_protection() users Ingo Molnar
2012-11-22 22:49 ` [PATCH 08/33] sched, numa, mm: Add last_cpu to page flags Ingo Molnar
2012-11-22 22:49 ` [PATCH 09/33] sched, mm, numa: Create generic NUMA fault infrastructure, with architectures overrides Ingo Molnar
2012-11-22 22:49 ` [PATCH 10/33] sched: Make find_busiest_queue() a method Ingo Molnar
2012-11-22 22:49 ` [PATCH 11/33] sched, numa, mm: Describe the NUMA scheduling problem formally Ingo Molnar
2012-11-22 22:49 ` [PATCH 12/33] numa, mm: Support NUMA hinting page faults from gup/gup_fast Ingo Molnar
2012-11-22 22:49 ` [PATCH 13/33] mm/migrate: Introduce migrate_misplaced_page() Ingo Molnar
2012-11-22 22:49 ` [PATCH 14/33] mm/migration: Improve migrate_misplaced_page() Ingo Molnar
2012-11-22 22:49 ` [PATCH 15/33] sched, numa, mm, arch: Add variable locality exception Ingo Molnar
2012-11-22 22:49 ` [PATCH 16/33] sched, numa, mm: Add credits for NUMA placement Ingo Molnar
2012-11-22 22:49 ` [PATCH 17/33] sched, mm, x86: Add the ARCH_SUPPORTS_NUMA_BALANCING flag Ingo Molnar
2012-11-22 22:49 ` [PATCH 18/33] sched, numa, mm: Add the scanning page fault machinery Ingo Molnar
2012-12-04 0:56 ` [patch] mm, mempolicy: Introduce spinlock to read shared policy tree David Rientjes
2012-12-20 18:34 ` Linus Torvalds
2012-12-20 22:55 ` David Rientjes
2012-12-21 13:47 ` Mel Gorman
2012-12-21 16:53 ` Linus Torvalds
2012-12-21 18:21 ` Hugh Dickins
2012-12-21 21:51 ` Linus Torvalds
2012-12-21 19:58 ` Mel Gorman
2012-12-21 22:02 ` Linus Torvalds
2012-12-21 23:10 ` Mel Gorman
2012-12-22 0:36 ` Linus Torvalds
2013-01-02 19:43 ` KOSAKI Motohiro
2012-11-22 22:49 ` [PATCH 19/33] sched: Add adaptive NUMA affinity support Ingo Molnar
2012-11-26 20:32 ` Sasha Levin [this message]
2012-11-22 22:49 ` [PATCH 20/33] sched: Implement constant, per task Working Set Sampling (WSS) rate Ingo Molnar
2012-11-22 22:49 ` [PATCH 21/33] sched, numa, mm: Count WS scanning against present PTEs, not virtual memory ranges Ingo Molnar
2012-11-22 22:49 ` [PATCH 22/33] sched: Implement slow start for working set sampling Ingo Molnar
2012-11-22 22:49 ` [PATCH 23/33] sched, numa, mm: Interleave shared tasks Ingo Molnar
2012-11-22 22:49 ` [PATCH 24/33] sched: Implement NUMA scanning backoff Ingo Molnar
2012-11-22 22:49 ` [PATCH 25/33] sched: Improve convergence Ingo Molnar
2012-11-22 22:49 ` [PATCH 26/33] sched: Introduce staged average NUMA faults Ingo Molnar
2012-11-22 22:49 ` [PATCH 27/33] sched: Track groups of shared tasks Ingo Molnar
2012-11-22 22:49 ` [PATCH 28/33] sched: Use the best-buddy 'ideal cpu' in balancing decisions Ingo Molnar
2012-11-22 22:49 ` [PATCH 29/33] sched, mm, mempolicy: Add per task mempolicy Ingo Molnar
2012-11-22 22:49 ` [PATCH 30/33] sched: Average the fault stats longer Ingo Molnar
2012-11-22 22:49 ` [PATCH 31/33] sched: Use the ideal CPU to drive active balancing Ingo Molnar
2012-11-22 22:49 ` [PATCH 32/33] sched: Add hysteresis to p->numa_shared Ingo Molnar
2012-11-22 22:49 ` [PATCH 33/33] sched: Track shared task's node groups and interleave their memory allocations Ingo Molnar
2012-11-22 22:53 ` [PATCH 00/33] Latest numa/core release, v17 Ingo Molnar
2012-11-23 6:47 ` Zhouping Liu
2012-11-23 17:32 ` Comparison between three trees (was: Latest numa/core release, v17) Mel Gorman
2012-11-25 8:47 ` Hillf Danton
2012-11-26 9:38 ` Mel Gorman
2012-11-25 23:37 ` Mel Gorman
2012-11-25 23:40 ` Mel Gorman
2012-11-26 13:33 ` Mel Gorman
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