The patch titled Subject: sched/numa, mm: do not try to migrate memory to memoryless nodes has been added to the -mm mm-hotfixes-unstable branch. Its filename is sched-numa-mm-do-not-try-to-migrate-memory-to-memoryless-nodes.patch

This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...

This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------ From: Byungchul Park byungchul@sk.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@sk.com Reviewed-by: Oscar Salvador osalvador@suse.de Reviewed-by: "Huang, Ying" ying.huang@intel.com Reviewed-by: Phil Auld pauld@redhat.com Cc: Benjamin Segall bsegall@google.com Cc: Daniel Bristot de Oliveira bristot@redhat.com Cc: Dietmar Eggemann dietmar.eggemann@arm.com Cc: Ingo Molnar mingo@redhat.com Cc: Juri Lelli juri.lelli@redhat.com Cc: Mel Gorman mgorman@suse.de Cc: Peter Zijlstra peterz@infradead.org Cc: Steven Rostedt rostedt@goodmis.org Cc: Valentin Schneider vschneid@redhat.com Cc: Vincent Guittot vincent.guittot@linaro.org Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-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. */ _

Patches currently in -mm which might be from byungchul@sk.com are

sched-numa-mm-do-not-try-to-migrate-memory-to-memoryless-nodes.patch mm-vmscan-dont-turn-on-cache_trim_mode-at-the-highest-scan-priority.patch