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>
Signed-off-by: Byungchul Park <[email protected]>
Reported-by: Hyeongtak Ji <[email protected]>
Cc: [email protected]
Fixes: c574bbe917036 ("NUMA balancing: optimize page placement for memory tiering system")
---
mm/migrate.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/mm/migrate.c b/mm/migrate.c
index fbc8586ed735..51ee6865b0f6 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -2825,6 +2825,14 @@ static int numamigrate_isolate_folio(pg_data_t *pgdat, struct folio *folio)
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;
--
2.17.1
On 2024/2/16 19:15, Byungchul Park wrote:
> 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>
>
> Signed-off-by: Byungchul Park <[email protected]>
> Reported-by: Hyeongtak Ji <[email protected]>
> Cc: [email protected]
> Fixes: c574bbe917036 ("NUMA balancing: optimize page placement for memory tiering system")
This means that there is no memory on the target node？ if so, we can add
a check at the beginning to avoid calling unnecessary
migrate_misplaced_folio().
diff --git a/mm/memory.c b/mm/memory.c
index e95503d7544e..a64a1aac463f 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -5182,7 +5182,7 @@ static vm_fault_t do_numa_page(struct vm_fault *vmf)
else
last_cpupid = folio_last_cpupid(folio);
target_nid = numa_migrate_prep(folio, vma, vmf->address, nid,
&flags);
- if (target_nid == NUMA_NO_NODE) {
+ if (target_nid == NUMA_NO_NODE || !node_state(target_nid,
N_MEMORY)) {
folio_put(folio);
goto out_map;
}
(similar changes for do_huge_pmd_numa_page())
> ---
> mm/migrate.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/mm/migrate.c b/mm/migrate.c
> index fbc8586ed735..51ee6865b0f6 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -2825,6 +2825,14 @@ static int numamigrate_isolate_folio(pg_data_t *pgdat, struct folio *folio)
> 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;
On Mon, Feb 19, 2024 at 02:25:11PM +0800, Baolin Wang wrote:
>
>
> On 2024/2/16 19:15, Byungchul Park wrote:
> > 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>
> >
> > Signed-off-by: Byungchul Park <[email protected]>
> > Reported-by: Hyeongtak Ji <[email protected]>
> > Cc: [email protected]
> > Fixes: c574bbe917036 ("NUMA balancing: optimize page placement for memory tiering system")
>
> This means that there is no memory on the target node？ if so, we can add a
> check at the beginning to avoid calling unnecessary
> migrate_misplaced_folio().
Right. However, the check is necessary no matter where it comes from.
FYI, the fix is going on in another thread:
https://lore.kernel.org/lkml/[email protected]/
https://lore.kernel.org/lkml/[email protected]/
Byungchul
> diff --git a/mm/memory.c b/mm/memory.c
> index e95503d7544e..a64a1aac463f 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -5182,7 +5182,7 @@ static vm_fault_t do_numa_page(struct vm_fault *vmf)
> else
> last_cpupid = folio_last_cpupid(folio);
> target_nid = numa_migrate_prep(folio, vma, vmf->address, nid,
> &flags);
> - if (target_nid == NUMA_NO_NODE) {
> + if (target_nid == NUMA_NO_NODE || !node_state(target_nid, N_MEMORY))
> {
> folio_put(folio);
> goto out_map;
> }
>
> (similar changes for do_huge_pmd_numa_page())
>
> > ---
> > mm/migrate.c | 8 ++++++++
> > 1 file changed, 8 insertions(+)
> >
> > diff --git a/mm/migrate.c b/mm/migrate.c
> > index fbc8586ed735..51ee6865b0f6 100644
> > --- a/mm/migrate.c
> > +++ b/mm/migrate.c
> > @@ -2825,6 +2825,14 @@ static int numamigrate_isolate_folio(pg_data_t *pgdat, struct folio *folio)
> > 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;
On Mon, Feb 19, 2024 at 02:25:11PM +0800, Baolin Wang wrote:
> This means that there is no memory on the target node？ if so, we can add a
> check at the beginning to avoid calling unnecessary
> migrate_misplaced_folio().
>
> diff --git a/mm/memory.c b/mm/memory.c
> index e95503d7544e..a64a1aac463f 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -5182,7 +5182,7 @@ static vm_fault_t do_numa_page(struct vm_fault *vmf)
> else
> last_cpupid = folio_last_cpupid(folio);
> target_nid = numa_migrate_prep(folio, vma, vmf->address, nid,
> &flags);
> - if (target_nid == NUMA_NO_NODE) {
> + if (target_nid == NUMA_NO_NODE || !node_state(target_nid, N_MEMORY))
> {
> folio_put(folio);
> goto out_map;
> }
>
> (similar changes for do_huge_pmd_numa_page())
With the check in place from [1], numa_migrate_prep() will also return
NUMA_NO_NODE, so no need for this one here.
And I did not check, but I assume that do_huge_pmd_numa_page() also ends
up calling numa_migrate_prep().
[1] https://lore.kernel.org/lkml/[email protected]/
--
Oscar Salvador
SUSE Labs
On 2024/2/19 16:11, Oscar Salvador wrote:
> On Mon, Feb 19, 2024 at 02:25:11PM +0800, Baolin Wang wrote:
>> This means that there is no memory on the target node？ if so, we can add a
>> check at the beginning to avoid calling unnecessary
>> migrate_misplaced_folio().
>>
>> diff --git a/mm/memory.c b/mm/memory.c
>> index e95503d7544e..a64a1aac463f 100644
>> --- a/mm/memory.c
>> +++ b/mm/memory.c
>> @@ -5182,7 +5182,7 @@ static vm_fault_t do_numa_page(struct vm_fault *vmf)
>> else
>> last_cpupid = folio_last_cpupid(folio);
>> target_nid = numa_migrate_prep(folio, vma, vmf->address, nid,
>> &flags);
>> - if (target_nid == NUMA_NO_NODE) {
>> + if (target_nid == NUMA_NO_NODE || !node_state(target_nid, N_MEMORY))
>> {
>> folio_put(folio);
>> goto out_map;
>> }
>>
>> (similar changes for do_huge_pmd_numa_page())
>
> With the check in place from [1], numa_migrate_prep() will also return
> NUMA_NO_NODE, so no need for this one here.
>
> And I did not check, but I assume that do_huge_pmd_numa_page() also ends
> up calling numa_migrate_prep().
>
> [1] https://lore.kernel.org/lkml/[email protected]/
Right. I missed this patch before. So with checking in
should_numa_migrate_memory(), I guess current changes in
numamigrate_isolate_folio() can also be dropped, it will never hit a
memoryless node after the patch [1], no?
Byungchul Park <[email protected]> writes:
> 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>
>
> Signed-off-by: Byungchul Park <[email protected]>
> Reported-by: Hyeongtak Ji <[email protected]>
> Cc: [email protected]
> Fixes: c574bbe917036 ("NUMA balancing: optimize page placement for memory tiering system")
> ---
> mm/migrate.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/mm/migrate.c b/mm/migrate.c
> index fbc8586ed735..51ee6865b0f6 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -2825,6 +2825,14 @@ static int numamigrate_isolate_folio(pg_data_t *pgdat, struct folio *folio)
> if (managed_zone(pgdat->node_zones + z))
> break;
> }
> +
> + /*
> + * If there are no managed zones, it should not proceed
> + * further.
> + */
> + if (z < 0)
> + return 0;
> +
I think that it's better to check pgdat->nr_zones directly earlier in
the function. That is a little easier to be understood.
> wakeup_kswapd(pgdat->node_zones + z, 0,
> folio_order(folio), ZONE_MOVABLE);
> return 0;
--
Best Regards,
Huang, Ying
On Tue, Feb 20, 2024 at 11:42:31AM +0800, Huang, Ying wrote:
> Byungchul Park <[email protected]> writes:
>
> > 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>
> >
> > Signed-off-by: Byungchul Park <[email protected]>
> > Reported-by: Hyeongtak Ji <[email protected]>
> > Cc: [email protected]
> > Fixes: c574bbe917036 ("NUMA balancing: optimize page placement for memory tiering system")
> > ---
> > mm/migrate.c | 8 ++++++++
> > 1 file changed, 8 insertions(+)
> >
> > diff --git a/mm/migrate.c b/mm/migrate.c
> > index fbc8586ed735..51ee6865b0f6 100644
> > --- a/mm/migrate.c
> > +++ b/mm/migrate.c
> > @@ -2825,6 +2825,14 @@ static int numamigrate_isolate_folio(pg_data_t *pgdat, struct folio *folio)
> > if (managed_zone(pgdat->node_zones + z))
> > break;
> > }
> > +
> > + /*
> > + * If there are no managed zones, it should not proceed
> > + * further.
> > + */
> > + if (z < 0)
> > + return 0;
> > +
>
> I think that it's better to check pgdat->nr_zones directly earlier in
> the function. That is a little easier to be understood.
No. No matter what the value of ->nr_zones is, the oops is going to
happen if there are no managed zones by any reason.
Byungchul
> > wakeup_kswapd(pgdat->node_zones + z, 0,
> > folio_order(folio), ZONE_MOVABLE);
> > return 0;
>
> --
> Best Regards,
> Huang, Ying
Byungchul Park <[email protected]> writes:
> On Tue, Feb 20, 2024 at 11:42:31AM +0800, Huang, Ying wrote:
>> Byungchul Park <[email protected]> writes:
>>
>> > 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>
>> >
>> > Signed-off-by: Byungchul Park <[email protected]>
>> > Reported-by: Hyeongtak Ji <[email protected]>
>> > Cc: [email protected]
>> > Fixes: c574bbe917036 ("NUMA balancing: optimize page placement for memory tiering system")
>> > ---
>> > mm/migrate.c | 8 ++++++++
>> > 1 file changed, 8 insertions(+)
>> >
>> > diff --git a/mm/migrate.c b/mm/migrate.c
>> > index fbc8586ed735..51ee6865b0f6 100644
>> > --- a/mm/migrate.c
>> > +++ b/mm/migrate.c
>> > @@ -2825,6 +2825,14 @@ static int numamigrate_isolate_folio(pg_data_t *pgdat, struct folio *folio)
>> > if (managed_zone(pgdat->node_zones + z))
>> > break;
>> > }
>> > +
>> > + /*
>> > + * If there are no managed zones, it should not proceed
>> > + * further.
>> > + */
>> > + if (z < 0)
>> > + return 0;
>> > +
>>
>> I think that it's better to check pgdat->nr_zones directly earlier in
>> the function. That is a little easier to be understood.
>
> No. No matter what the value of ->nr_zones is, the oops is going to
> happen if there are no managed zones by any reason.
Yes. You are right. Sorry for noise.
--
Best Regards,
Huang, Ying
> Byungchul
>
>> > wakeup_kswapd(pgdat->node_zones + z, 0,
>> > folio_order(folio), ZONE_MOVABLE);
>> > return 0;
>>
>> --
>> Best Regards,
>> Huang, Ying