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Message-ID: <20240220015343.GD65758@system.software.com>
Date: Tue, 20 Feb 2024 10:53:43 +0900
From: Byungchul Park <byungchul@...com>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: "Huang, Ying" <ying.huang@...el.com>, mingo@...hat.com,
peterz@...radead.org, juri.lelli@...hat.com,
vincent.guittot@...aro.org, dietmar.eggemann@....com,
rostedt@...dmis.org, bsegall@...gle.com, mgorman@...e.de,
bristot@...hat.com, vschneid@...hat.com,
linux-kernel@...r.kernel.org, linux-mm@...ck.org,
kernel_team@...ynix.com
Subject: Re: [PATCH v4] sched/numa, mm: do not try to migrate memory to
memoryless nodes
On Mon, Feb 19, 2024 at 05:45:08PM -0800, Andrew Morton wrote:
> On Mon, 19 Feb 2024 16:43:36 +0800 "Huang, Ying" <ying.huang@...el.com> wrote:
>
> > > + /*
> > > + * Cannot migrate to memoryless nodes.
> > > + */
> > > + 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.
> >
> > Good catch!
> >
> > IIUC, you will use patch as fix to the issue in
> >
> > https://lore.kernel.org/lkml/20240216111502.79759-1-byungchul@sk.com/
> >
> > If so, we need the Fixes: tag to make it land in -stable properly.
>
> Yes, this changelog is missing rather a lot of important information.
This is not the root cause fix any more but just optimization. That's
why I didn't add Fixes: tag and cc stable@...r.kernel.org in here.
Instead, I added Fixes: tag and cc'ed stable@...r.kernel.org in the real
fix patch. check the following link please:
https://lore.kernel.org/lkml/20240216111502.79759-1-byungchul@sk.com/
Byungchul
> I pulled together the below, please check.
>
>
> From: Byungchul Park <byungchul@...com>
> Subject: sched/numa, mm: do not try to migrate memory to memoryless nodes
> Date: Mon, 19 Feb 2024 13:10:47 +0900
>
> With numa balancing on, when a numa system is running where a numa node
> doesn't have its local memory so it has no managed zones, the following
> oops has been observed. It's because wakeup_kswapd() is called with a
> wrong zone index, -1. Fixed it by checking the index before calling
> wakeup_kswapd().
>
> > 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>
>
> Fix this by avoiding any attempt to migrate memory to memoryless nodes.
>
> Link: https://lkml.kernel.org/r/20240219041920.1183-1-byungchul@sk.com
> Link: https://lkml.kernel.org/r/20240216111502.79759-1-byungchul@sk.com
> Fixes: c574bbe917036 ("NUMA balancing: optimize page placement for memory tiering system")
> Signed-off-by: Byungchul Park <byungchul@...com>
> Reviewed-by: Oscar Salvador <osalvador@...e.de>
> Reviewed-by: "Huang, Ying" <ying.huang@...el.com>
> Reviewed-by: Phil Auld <pauld@...hat.com>
> Cc: Benjamin Segall <bsegall@...gle.com>
> Cc: Daniel Bristot de Oliveira <bristot@...hat.com>
> Cc: Dietmar Eggemann <dietmar.eggemann@....com>
> Cc: Ingo Molnar <mingo@...hat.com>
> Cc: Juri Lelli <juri.lelli@...hat.com>
> Cc: Mel Gorman <mgorman@...e.de>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Cc: Steven Rostedt <rostedt@...dmis.org>
> Cc: Valentin Schneider <vschneid@...hat.com>
> Cc: Vincent Guittot <vincent.guittot@...aro.org>
> Cc: <stable@...r.kernel.org>
> Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
> ---
>
> kernel/sched/fair.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> --- a/kernel/sched/fair.c~sched-numa-mm-do-not-try-to-migrate-memory-to-memoryless-nodes
> +++ a/kernel/sched/fair.c
> @@ -1831,6 +1831,12 @@ bool should_numa_migrate_memory(struct t
> int last_cpupid, this_cpupid;
>
> /*
> + * Cannot migrate to memoryless nodes.
> + */
> + 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.
> */
> _
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