diff mbox series

[v2] sched/numa, mm: do not promote folios to nodes not set N_MEMORY

Message ID 20240216073340.55404-1-byungchul@sk.com
State New
Headers
Series [v2] sched/numa, mm: do not promote folios to nodes not set N_MEMORY |

Commit Message

Byungchul Park Feb. 16, 2024, 7:33 a.m. UTC 
  Changes from v1:
	1. Trim the verbose oops in the commit message. (feedbacked by
	   Phil Auld)
	2. Rewrite a comment in code. (feedbacked by Phil Auld)

--->8---
From 6830b59db267a31b78f6f09af12ae0e3132b4bca Mon Sep 17 00:00:00 2001
From: Byungchul Park <byungchul@sk.com>
Date: Fri, 16 Feb 2024 16:26:23 +0900
Subject: [PATCH v2] sched/numa, mm: do not promote folios to nodes not set N_MEMORY

While running qemu with a configuration where some CPUs don't have their
local memory and with a kernel numa balancing on, the following oops has
been observed. It's because of null pointers of ->zone_pgdat of zones of
those nodes that are not initialized properly at booting time. So should
avoid nodes not set N_MEMORY from getting promoted.

> BUG: unable to handle page fault for address: 00000000000033f3
> #PF: supervisor read access in kernel mode
> #PF: error_code(0x0000) - not-present page
> PGD 0 P4D 0
> Oops: 0000 [#1] PREEMPT SMP NOPTI
> CPU: 2 PID: 895 Comm: masim Not tainted 6.6.0-dirty #255
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
>    rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014
> RIP: 0010:wakeup_kswapd (./linux/mm/vmscan.c:7812)
> Code: (omitted)
> RSP: 0000:ffffc90004257d58 EFLAGS: 00010286
> RAX: ffffffffffffffff RBX: ffff88883fff0480 RCX: 0000000000000003
> RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88883fff0480
> RBP: ffffffffffffffff R08: ff0003ffffffffff R09: ffffffffffffffff
> R10: ffff888106c95540 R11: 0000000055555554 R12: 0000000000000003
> R13: 0000000000000000 R14: 0000000000000000 R15: ffff88883fff0940
> FS:  00007fc4b8124740(0000) GS:ffff888827c00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00000000000033f3 CR3: 000000026cc08004 CR4: 0000000000770ee0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> PKRU: 55555554
> Call Trace:
>  <TASK>
> ? __die
> ? page_fault_oops
> ? __pte_offset_map_lock
> ? exc_page_fault
> ? asm_exc_page_fault
> ? wakeup_kswapd
> migrate_misplaced_page
> __handle_mm_fault
> handle_mm_fault
> do_user_addr_fault
> exc_page_fault
> asm_exc_page_fault
> RIP: 0033:0x55b897ba0808
> Code: (omitted)
> RSP: 002b:00007ffeefa821a0 EFLAGS: 00010287
> RAX: 000055b89983acd0 RBX: 00007ffeefa823f8 RCX: 000055b89983acd0
> RDX: 00007fc2f8122010 RSI: 0000000000020000 RDI: 000055b89983acd0
> RBP: 00007ffeefa821a0 R08: 0000000000000037 R09: 0000000000000075
> R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000
> R13: 00007ffeefa82410 R14: 000055b897ba5dd8 R15: 00007fc4b8340000
>  </TASK>

Signed-off-by: Byungchul Park <byungchul@sk.com>
Reported-by: Hyeongtak Ji <hyeongtak.ji@sk.com>
---
 kernel/sched/fair.c | 9 +++++++++
 1 file changed, 9 insertions(+)

Comments

David Hildenbrand Feb. 16, 2024, 9:07 a.m. UTC | #1 
On 16.02.24 08:33, Byungchul Park wrote:
> Changes from v1:
> 	1. Trim the verbose oops in the commit message. (feedbacked by
> 	   Phil Auld)
> 	2. Rewrite a comment in code. (feedbacked by Phil Auld)
> 
> --->8---
>  From 6830b59db267a31b78f6f09af12ae0e3132b4bca Mon Sep 17 00:00:00 2001
> From: Byungchul Park <byungchul@sk.com>
> Date: Fri, 16 Feb 2024 16:26:23 +0900
> Subject: [PATCH v2] sched/numa, mm: do not promote folios to nodes not set N_MEMORY
> 
> While running qemu with a configuration where some CPUs don't have their
> local memory and with a kernel numa balancing on, the following oops has
> been observed. It's because of null pointers of ->zone_pgdat of zones of
> those nodes that are not initialized properly at booting time. So should
> avoid nodes not set N_MEMORY from getting promoted.
> 
>> BUG: unable to handle page fault for address: 00000000000033f3
>> #PF: supervisor read access in kernel mode
>> #PF: error_code(0x0000) - not-present page
>> PGD 0 P4D 0
>> Oops: 0000 [#1] PREEMPT SMP NOPTI
>> CPU: 2 PID: 895 Comm: masim Not tainted 6.6.0-dirty #255
>> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
>>     rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014
>> RIP: 0010:wakeup_kswapd (./linux/mm/vmscan.c:7812)
>> Code: (omitted)
>> RSP: 0000:ffffc90004257d58 EFLAGS: 00010286
>> RAX: ffffffffffffffff RBX: ffff88883fff0480 RCX: 0000000000000003
>> RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88883fff0480
>> RBP: ffffffffffffffff R08: ff0003ffffffffff R09: ffffffffffffffff
>> R10: ffff888106c95540 R11: 0000000055555554 R12: 0000000000000003
>> R13: 0000000000000000 R14: 0000000000000000 R15: ffff88883fff0940
>> FS:  00007fc4b8124740(0000) GS:ffff888827c00000(0000) knlGS:0000000000000000
>> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> CR2: 00000000000033f3 CR3: 000000026cc08004 CR4: 0000000000770ee0
>> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>> PKRU: 55555554
>> Call Trace:
>>   <TASK>
>> ? __die
>> ? page_fault_oops
>> ? __pte_offset_map_lock
>> ? exc_page_fault
>> ? asm_exc_page_fault
>> ? wakeup_kswapd
>> migrate_misplaced_page
>> __handle_mm_fault
>> handle_mm_fault
>> do_user_addr_fault
>> exc_page_fault
>> asm_exc_page_fault
>> RIP: 0033:0x55b897ba0808
>> Code: (omitted)
>> RSP: 002b:00007ffeefa821a0 EFLAGS: 00010287
>> RAX: 000055b89983acd0 RBX: 00007ffeefa823f8 RCX: 000055b89983acd0
>> RDX: 00007fc2f8122010 RSI: 0000000000020000 RDI: 000055b89983acd0
>> RBP: 00007ffeefa821a0 R08: 0000000000000037 R09: 0000000000000075
>> R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000
>> R13: 00007ffeefa82410 R14: 000055b897ba5dd8 R15: 00007fc4b8340000
>>   </TASK>
> 

This sounds like we need a Fixes: and want to CC stable?
Byungchul Park Feb. 16, 2024, 9:13 a.m. UTC | #2 
On Fri, Feb 16, 2024 at 10:07:53AM +0100, David Hildenbrand wrote:
> On 16.02.24 08:33, Byungchul Park wrote:
> > Changes from v1:
> > 	1. Trim the verbose oops in the commit message. (feedbacked by
> > 	   Phil Auld)
> > 	2. Rewrite a comment in code. (feedbacked by Phil Auld)
> > 
> > --->8---
> >  From 6830b59db267a31b78f6f09af12ae0e3132b4bca Mon Sep 17 00:00:00 2001
> > From: Byungchul Park <byungchul@sk.com>
> > Date: Fri, 16 Feb 2024 16:26:23 +0900
> > Subject: [PATCH v2] sched/numa, mm: do not promote folios to nodes not set N_MEMORY
> > 
> > While running qemu with a configuration where some CPUs don't have their
> > local memory and with a kernel numa balancing on, the following oops has
> > been observed. It's because of null pointers of ->zone_pgdat of zones of
> > those nodes that are not initialized properly at booting time. So should
> > avoid nodes not set N_MEMORY from getting promoted.
> > 
> > > BUG: unable to handle page fault for address: 00000000000033f3
> > > #PF: supervisor read access in kernel mode
> > > #PF: error_code(0x0000) - not-present page
> > > PGD 0 P4D 0
> > > Oops: 0000 [#1] PREEMPT SMP NOPTI
> > > CPU: 2 PID: 895 Comm: masim Not tainted 6.6.0-dirty #255
> > > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
> > >     rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014
> > > RIP: 0010:wakeup_kswapd (./linux/mm/vmscan.c:7812)
> > > Code: (omitted)
> > > RSP: 0000:ffffc90004257d58 EFLAGS: 00010286
> > > RAX: ffffffffffffffff RBX: ffff88883fff0480 RCX: 0000000000000003
> > > RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88883fff0480
> > > RBP: ffffffffffffffff R08: ff0003ffffffffff R09: ffffffffffffffff
> > > R10: ffff888106c95540 R11: 0000000055555554 R12: 0000000000000003
> > > R13: 0000000000000000 R14: 0000000000000000 R15: ffff88883fff0940
> > > FS:  00007fc4b8124740(0000) GS:ffff888827c00000(0000) knlGS:0000000000000000
> > > CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > > CR2: 00000000000033f3 CR3: 000000026cc08004 CR4: 0000000000770ee0
> > > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> > > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> > > PKRU: 55555554
> > > Call Trace:
> > >   <TASK>
> > > ? __die
> > > ? page_fault_oops
> > > ? __pte_offset_map_lock
> > > ? exc_page_fault
> > > ? asm_exc_page_fault
> > > ? wakeup_kswapd
> > > migrate_misplaced_page
> > > __handle_mm_fault
> > > handle_mm_fault
> > > do_user_addr_fault
> > > exc_page_fault
> > > asm_exc_page_fault
> > > RIP: 0033:0x55b897ba0808
> > > Code: (omitted)
> > > RSP: 002b:00007ffeefa821a0 EFLAGS: 00010287
> > > RAX: 000055b89983acd0 RBX: 00007ffeefa823f8 RCX: 000055b89983acd0
> > > RDX: 00007fc2f8122010 RSI: 0000000000020000 RDI: 000055b89983acd0
> > > RBP: 00007ffeefa821a0 R08: 0000000000000037 R09: 0000000000000075
> > > R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000
> > > R13: 00007ffeefa82410 R14: 000055b897ba5dd8 R15: 00007fc4b8340000
> > >   </TASK>
> > 
> 
> This sounds like we need a Fixes: and want to CC stable?

Sure. I will CC stable at the next spin - might need to rewrite the
reason.

	Byungchul

> -- 
> Cheers,
> 
> David / dhildenb
diff mbox series

Patch

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index d7a3c63a2171..859ef78ef72b 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -1828,6 +1828,15 @@  bool should_numa_migrate_memory(struct task_struct *p, struct folio *folio,
 	int dst_nid = cpu_to_node(dst_cpu);
 	int last_cpupid, this_cpupid;
 
+	/*
+	 * A node of dst_nid might not have its local memory. Promoting
+	 * a folio to the node is meaningless. What's even worse, oops
+	 * can be observed by the null pointer of ->zone_pgdat in
+	 * various points of the code during migration.
+	 */
+	if (!node_state(dst_nid, N_MEMORY))
+		return false;
+
 	/*
 	 * The pages in slow memory node should be migrated according
 	 * to hot/cold instead of private/shared.