The patch titled
Subject: mm/vmscan: fix a bug calling wakeup_kswapd() with a wrong zone index
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
mm-vmscan-fix-a-bug-calling-wakeup_kswapd-with-a-wrong-zone-index.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-vmscan-fix-a-bug-calling-wakeup_kswapd-with-a-wrong-zone-index.patch
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@xxxxxx>
Subject: mm/vmscan: fix a bug calling wakeup_kswapd() with a wrong zone index
Date: Fri, 16 Feb 2024 20:15:02 +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>
Link: https://lkml.kernel.org/r/20240216111502.79759-1-byungchul@xxxxxx
Signed-off-by: Byungchul Park <byungchul@xxxxxx>
Reported-by: Hyeongtak Ji <hyeongtak.ji@xxxxxx>
Fixes: c574bbe917036 ("NUMA balancing: optimize page placement for memory tiering system")
Cc: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Cc: "Huang, Ying" <ying.huang@xxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/migrate.c | 8 ++++++++
1 file changed, 8 insertions(+)
--- a/mm/migrate.c~mm-vmscan-fix-a-bug-calling-wakeup_kswapd-with-a-wrong-zone-index
+++ a/mm/migrate.c
@@ -2519,6 +2519,14 @@ static int numamigrate_isolate_folio(pg_
if (managed_zone(pgdat->node_zones + z))
break;
}
+
+ /*
+ * If there are no managed zones, it should not proceed
+ * further.
+ */
+ if (z < 0)
+ return 0;
+
wakeup_kswapd(pgdat->node_zones + z, 0,
folio_order(folio), ZONE_MOVABLE);
return 0;
_
Patches currently in -mm which might be from byungchul@xxxxxx are
mm-vmscan-fix-a-bug-calling-wakeup_kswapd-with-a-wrong-zone-index.patch
mm-vmscan-dont-turn-on-cache_trim_mode-at-the-highest-scan-priority.patch
sched-numa-mm-do-not-try-to-migrate-memory-to-memoryless-nodes.patch
