* mm problems with 5.15.9-dovetail1
@ 2022-01-06 8:46 Jan Kiszka
2022-01-06 19:21 ` Philippe Gerum
0 siblings, 1 reply; 7+ messages in thread
From: Jan Kiszka @ 2022-01-06 8:46 UTC (permalink / raw)
To: Philippe Gerum, Xenomai
Hi Philippe,
seems we have some issue with the new 5.15 dovetail kernel, see e.g.
https://source.denx.de/Xenomai/xenomai-images/-/jobs/371693
https://source.denx.de/Xenomai/xenomai-images/-/jobs/371694
https://source.denx.de/Xenomai/xenomai-images/-/jobs/371695
(kernel BUG at mm/rmap.c:1049!)
Or are there changes needed on Xenomai side?
Jan
--
Siemens AG, Technology
Competence Center Embedded Linux
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: mm problems with 5.15.9-dovetail1
2022-01-06 8:46 mm problems with 5.15.9-dovetail1 Jan Kiszka
@ 2022-01-06 19:21 ` Philippe Gerum
2022-01-08 15:21 ` Philippe Gerum
0 siblings, 1 reply; 7+ messages in thread
From: Philippe Gerum @ 2022-01-06 19:21 UTC (permalink / raw)
To: Jan Kiszka; +Cc: Xenomai
Hi,
Jan Kiszka <jan.kiszka@siemens.com> writes:
> Hi Philippe,
>
> seems we have some issue with the new 5.15 dovetail kernel, see e.g.
>
> https://source.denx.de/Xenomai/xenomai-images/-/jobs/371693
> https://source.denx.de/Xenomai/xenomai-images/-/jobs/371694
> https://source.denx.de/Xenomai/xenomai-images/-/jobs/371695
> (kernel BUG at mm/rmap.c:1049!)
>
> Or are there changes needed on Xenomai side?
Nope. Plain bug I'd say. I'll have look at this in a couple of days.
--
Philippe.
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: mm problems with 5.15.9-dovetail1
2022-01-06 19:21 ` Philippe Gerum
@ 2022-01-08 15:21 ` Philippe Gerum
2022-01-08 15:36 ` Philippe Gerum
0 siblings, 1 reply; 7+ messages in thread
From: Philippe Gerum @ 2022-01-08 15:21 UTC (permalink / raw)
To: Jan Kiszka; +Cc: Xenomai
Philippe Gerum <rpm@xenomai.org> writes:
> Hi,
>
> Jan Kiszka <jan.kiszka@siemens.com> writes:
>
>> Hi Philippe,
>>
>> seems we have some issue with the new 5.15 dovetail kernel, see e.g.
>>
>> https://source.denx.de/Xenomai/xenomai-images/-/jobs/371693
>> https://source.denx.de/Xenomai/xenomai-images/-/jobs/371694
>> https://source.denx.de/Xenomai/xenomai-images/-/jobs/371695
>> (kernel BUG at mm/rmap.c:1049!)
>>
>> Or are there changes needed on Xenomai side?
>
> Nope. Plain bug I'd say. I'll have look at this in a couple of days.
posix_fork is triggering the bug. The logic disabling COW for dovetailed
tasks breaks with Cobalt over 5.15, but does not with EVL which explains
why I did not notice earlier. Working on this.
--
Philippe.
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: mm problems with 5.15.9-dovetail1
2022-01-08 15:21 ` Philippe Gerum
@ 2022-01-08 15:36 ` Philippe Gerum
2022-01-08 15:45 ` Philippe Gerum
2022-01-08 15:49 ` Philippe Gerum
0 siblings, 2 replies; 7+ messages in thread
From: Philippe Gerum @ 2022-01-08 15:36 UTC (permalink / raw)
To: Jan Kiszka; +Cc: xenomai
Philippe Gerum via Xenomai <xenomai@xenomai.org> writes:
> Philippe Gerum <rpm@xenomai.org> writes:
>
>> Hi,
>>
>> Jan Kiszka <jan.kiszka@siemens.com> writes:
>>
>>> Hi Philippe,
>>>
>>> seems we have some issue with the new 5.15 dovetail kernel, see e.g.
>>>
>>> https://source.denx.de/Xenomai/xenomai-images/-/jobs/371693
>>> https://source.denx.de/Xenomai/xenomai-images/-/jobs/371694
>>> https://source.denx.de/Xenomai/xenomai-images/-/jobs/371695
>>> (kernel BUG at mm/rmap.c:1049!)
>>>
>>> Or are there changes needed on Xenomai side?
>>
>> Nope. Plain bug I'd say. I'll have look at this in a couple of days.
>
> posix_fork is triggering the bug. The logic disabling COW for dovetailed
> tasks breaks with Cobalt over 5.15, but does not with EVL which explains
> why I did not notice earlier. Working on this.
Can you confirm this helps on your end?
Thanks,
commit 075d00feb7c2987a972aa4bc34d2a3107ec20307 (HEAD -> rebase/v5.15-dovetail)
Author: Philippe Gerum <rpm@xenomai.org>
Date: Sat Jan 8 16:30:24 2022 +0100
dovetail: mm: fix logic of COW-disabling check
COW-disabling for a dovetailed task does not depend on the pinning
status of the source page considered by copy_present_page(). Decouple
both checks, which fixes the following kernel splat on fork() from a
dovetailed task:
[ 18.376448] ------------[ cut here ]------------
[ 18.376915] kernel BUG at mm/rmap.c:1049!
[ 18.377259] invalid opcode: 0000 [#1] PREEMPT SMP NOPTI IRQ_PIPELINE
[ 18.377262] CPU: 0 PID: 121 Comm: smokey Not tainted 5.15.9+ #12
[ 18.377264] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-4.fc34 04/01/2014
[ 18.377265] IRQ stage: Linux
[ 18.377266] RIP: 0010:__page_set_anon_rmap+0x59/0x70
[ 18.377271] Code: c9 74 22 48 83 c0 01 48 89 43 18 f6 47 52 40 75 1b 48 2b 17 48 c1 ea 0c 48 03 97 98 00 00 00 48 89 53 20 5b c3 48 8b 00 eb d9 <0f> 0b 48 89 d6 e8 ad c6 01 00 48 89 c2 eb e6 0f 1f 84 00 00 00 00
[ 18.377273] RSP: 0018:ffffc90000b0bb50 EFLAGS: 00010246
[ 18.377275] RAX: 0000000000000000 RBX: 000000010498f000 RCX: 0000000000000001
[ 18.377276] RDX: 00007fe623795000 RSI: ffff888102ab5398 RDI: ffffea00041263c0
[ 18.377277] RBP: 0000000000000000 R08: 0000000000000000 R09: ffff8881029da958
[ 18.377277] R10: 0000000000000000 R11: 0000000000000000 R12: ffff888102aa3ca8
[ 18.377278] R13: ffff888102abaca8 R14: ffffea00041263c0 R15: 00007fe623795000
[ 18.377281] FS: 00007fe623815740(0000) GS:ffff888237c00000(0000) knlGS:0000000000000000
[ 18.377284] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 18.377285] CR2: 00007ffef0186000 CR3: 0000000102320000 CR4: 00000000000406f0
[ 18.377286] Call Trace:
[ 18.377287] <TASK>
[ 18.377287] copy_pte_range+0x646/0x8c0
[ 18.377292] copy_pud_range+0x20a/0x2b0
[ 18.377294] copy_page_range+0x10f/0x2e0
[ 18.377297] ? dup_mmap+0x232/0x4e0
[ 18.377300] dup_mmap+0x3a6/0x4e0
[ 18.377303] dup_mm.isra.0+0x52/0xf0
[ 18.377304] copy_process+0x169e/0x1920
[ 18.377307] kernel_clone+0x4f/0x3e0
[ 18.377309] ? cobalt_thread_setschedparam_ex+0x200/0x200
[ 18.377312] ? rcu_read_lock_sched_held+0x57/0x80
[ 18.377315] ? handle_root_syscall+0x269/0x440
[ 18.377319] __do_sys_clone+0x52/0x60
[ 18.377321] do_syscall_64+0x4d/0xa0
[ 18.377324] entry_SYSCALL_64_after_hwframe+0x44/0xae
Signed-off-by: Philippe Gerum <rpm@xenomai.org>
diff --git a/mm/memory.c b/mm/memory.c
index 0e3e2228f67ff8f..1c4fce2b4bdf1db 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -904,9 +904,10 @@ copy_present_page(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma
* process, we don't want to impose the COW-induced latency on
* it: make sure the child gets its own copy of the page.
*/
- if (likely(!page_needs_cow_for_dma(src_vma, page) &&
- (!dovetailing() || !test_bit(MMF_DOVETAILED,
- &src_vma->vm_mm->flags))))
+ if (likely(!page_needs_cow_for_dma(src_vma, page)))
+ return 1;
+
+ if (dovetailing() & test_bit(MMF_DOVETAILED, &src_vma->vm_mm->flags))
return 1;
new_page = *prealloc;
--
Philippe.
^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: mm problems with 5.15.9-dovetail1
2022-01-08 15:36 ` Philippe Gerum
@ 2022-01-08 15:45 ` Philippe Gerum
2022-01-08 15:49 ` Philippe Gerum
1 sibling, 0 replies; 7+ messages in thread
From: Philippe Gerum @ 2022-01-08 15:45 UTC (permalink / raw)
To: Jan Kiszka, xenomai
Philippe Gerum via Xenomai <xenomai@xenomai.org> writes:
> Philippe Gerum via Xenomai <xenomai@xenomai.org> writes:
>
>> Philippe Gerum <rpm@xenomai.org> writes:
>>
>>> Hi,
>>>
>>> Jan Kiszka <jan.kiszka@siemens.com> writes:
>>>
>>>> Hi Philippe,
>>>>
>>>> seems we have some issue with the new 5.15 dovetail kernel, see e.g.
>>>>
>>>> https://source.denx.de/Xenomai/xenomai-images/-/jobs/371693
>>>> https://source.denx.de/Xenomai/xenomai-images/-/jobs/371694
>>>> https://source.denx.de/Xenomai/xenomai-images/-/jobs/371695
>>>> (kernel BUG at mm/rmap.c:1049!)
>>>>
>>>> Or are there changes needed on Xenomai side?
>>>
>>> Nope. Plain bug I'd say. I'll have look at this in a couple of days.
>>
>> posix_fork is triggering the bug. The logic disabling COW for dovetailed
>> tasks breaks with Cobalt over 5.15, but does not with EVL which explains
>> why I did not notice earlier. Working on this.
This bug was introduced in Dovetail for kernel v5.13, so it has no
impact on xenomai3 users who run v5.10.y.
--
Philippe.
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: mm problems with 5.15.9-dovetail1
2022-01-08 15:36 ` Philippe Gerum
2022-01-08 15:45 ` Philippe Gerum
@ 2022-01-08 15:49 ` Philippe Gerum
2022-01-08 15:54 ` Philippe Gerum
1 sibling, 1 reply; 7+ messages in thread
From: Philippe Gerum @ 2022-01-08 15:49 UTC (permalink / raw)
To: Jan Kiszka; +Cc: xenomai
Philippe Gerum <rpm@xenomai.org> writes:
> Philippe Gerum via Xenomai <xenomai@xenomai.org> writes:
>
>> Philippe Gerum <rpm@xenomai.org> writes:
>>
>>> Hi,
>>>
>>> Jan Kiszka <jan.kiszka@siemens.com> writes:
>>>
>>>> Hi Philippe,
>>>>
>>>> seems we have some issue with the new 5.15 dovetail kernel, see e.g.
>>>>
>>>> https://source.denx.de/Xenomai/xenomai-images/-/jobs/371693
>>>> https://source.denx.de/Xenomai/xenomai-images/-/jobs/371694
>>>> https://source.denx.de/Xenomai/xenomai-images/-/jobs/371695
>>>> (kernel BUG at mm/rmap.c:1049!)
>>>>
>>>> Or are there changes needed on Xenomai side?
>>>
>>> Nope. Plain bug I'd say. I'll have look at this in a couple of days.
>>
>> posix_fork is triggering the bug. The logic disabling COW for dovetailed
>> tasks breaks with Cobalt over 5.15, but does not with EVL which explains
>> why I did not notice earlier. Working on this.
>
> Can you confirm this helps on your end?
>
Nope, that fix is broken. Please ignore.
--
Philippe.
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: mm problems with 5.15.9-dovetail1
2022-01-08 15:49 ` Philippe Gerum
@ 2022-01-08 15:54 ` Philippe Gerum
0 siblings, 0 replies; 7+ messages in thread
From: Philippe Gerum @ 2022-01-08 15:54 UTC (permalink / raw)
To: Philippe Gerum; +Cc: Jan Kiszka, xenomai
Philippe Gerum via Xenomai <xenomai@xenomai.org> writes:
> Philippe Gerum <rpm@xenomai.org> writes:
>
>> Philippe Gerum via Xenomai <xenomai@xenomai.org> writes:
>>
>>> Philippe Gerum <rpm@xenomai.org> writes:
>>>
>>>> Hi,
>>>>
>>>> Jan Kiszka <jan.kiszka@siemens.com> writes:
>>>>
>>>>> Hi Philippe,
>>>>>
>>>>> seems we have some issue with the new 5.15 dovetail kernel, see e.g.
>>>>>
>>>>> https://source.denx.de/Xenomai/xenomai-images/-/jobs/371693
>>>>> https://source.denx.de/Xenomai/xenomai-images/-/jobs/371694
>>>>> https://source.denx.de/Xenomai/xenomai-images/-/jobs/371695
>>>>> (kernel BUG at mm/rmap.c:1049!)
>>>>>
>>>>> Or are there changes needed on Xenomai side?
>>>>
>>>> Nope. Plain bug I'd say. I'll have look at this in a couple of days.
>>>
>>> posix_fork is triggering the bug. The logic disabling COW for dovetailed
>>> tasks breaks with Cobalt over 5.15, but does not with EVL which explains
>>> why I did not notice earlier. Working on this.
>>
>> Can you confirm this helps on your end?
>>
>
> Nope, that fix is broken. Please ignore.
Please try this patch instead:
commit 5dbd6d7869be593bc1a2f3abccccef507acfc8a5 (HEAD -> rebase/v5.15-dovetail)
Author: Philippe Gerum <rpm@xenomai.org>
Date: Sat Jan 8 16:30:24 2022 +0100
dovetail: mm: fix logic of COW-disabling check
COW-disabling for a dovetailed task does not depend on the pinning
status of the source page considered by copy_present_page(). Decouple
both checks, which fixes the following kernel splat on fork() from a
dovetailed task:
[ 18.376448] ------------[ cut here ]------------
[ 18.376915] kernel BUG at mm/rmap.c:1049!
[ 18.377259] invalid opcode: 0000 [#1] PREEMPT SMP NOPTI IRQ_PIPELINE
[ 18.377262] CPU: 0 PID: 121 Comm: smokey Not tainted 5.15.9+ #12
[ 18.377264] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-4.fc34 04/01/2014
[ 18.377265] IRQ stage: Linux
[ 18.377266] RIP: 0010:__page_set_anon_rmap+0x59/0x70
[ 18.377271] Code: c9 74 22 48 83 c0 01 48 89 43 18 f6 47 52 40 75 1b 48 2b 17 48 c1 ea 0c 48 03 97 98 00 00 00 48 89 53 20 5b c3 48 8b 00 eb d9 <0f> 0b 48 89 d6 e8 ad c6 01 00 48 89 c2 eb e6 0f 1f 84 00 00 00 00
[ 18.377273] RSP: 0018:ffffc90000b0bb50 EFLAGS: 00010246
[ 18.377275] RAX: 0000000000000000 RBX: 000000010498f000 RCX: 0000000000000001
[ 18.377276] RDX: 00007fe623795000 RSI: ffff888102ab5398 RDI: ffffea00041263c0
[ 18.377277] RBP: 0000000000000000 R08: 0000000000000000 R09: ffff8881029da958
[ 18.377277] R10: 0000000000000000 R11: 0000000000000000 R12: ffff888102aa3ca8
[ 18.377278] R13: ffff888102abaca8 R14: ffffea00041263c0 R15: 00007fe623795000
[ 18.377281] FS: 00007fe623815740(0000) GS:ffff888237c00000(0000) knlGS:0000000000000000
[ 18.377284] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 18.377285] CR2: 00007ffef0186000 CR3: 0000000102320000 CR4: 00000000000406f0
[ 18.377286] Call Trace:
[ 18.377287] <TASK>
[ 18.377287] copy_pte_range+0x646/0x8c0
[ 18.377292] copy_pud_range+0x20a/0x2b0
[ 18.377294] copy_page_range+0x10f/0x2e0
[ 18.377297] ? dup_mmap+0x232/0x4e0
[ 18.377300] dup_mmap+0x3a6/0x4e0
[ 18.377303] dup_mm.isra.0+0x52/0xf0
[ 18.377304] copy_process+0x169e/0x1920
[ 18.377307] kernel_clone+0x4f/0x3e0
[ 18.377309] ? cobalt_thread_setschedparam_ex+0x200/0x200
[ 18.377312] ? rcu_read_lock_sched_held+0x57/0x80
[ 18.377315] ? handle_root_syscall+0x269/0x440
[ 18.377319] __do_sys_clone+0x52/0x60
[ 18.377321] do_syscall_64+0x4d/0xa0
[ 18.377324] entry_SYSCALL_64_after_hwframe+0x44/0xae
Signed-off-by: Philippe Gerum <rpm@xenomai.org>
diff --git a/mm/memory.c b/mm/memory.c
index 0e3e2228f67ff8f..66d2eef80358505 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -904,9 +904,10 @@ copy_present_page(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma
* process, we don't want to impose the COW-induced latency on
* it: make sure the child gets its own copy of the page.
*/
- if (likely(!page_needs_cow_for_dma(src_vma, page) &&
- (!dovetailing() || !test_bit(MMF_DOVETAILED,
- &src_vma->vm_mm->flags))))
+ if (likely(!page_needs_cow_for_dma(src_vma, page)))
+ return 1;
+
+ if (dovetailing() && test_bit(MMF_DOVETAILED, &src_vma->vm_mm->flags))
return 1;
new_page = *prealloc;
--
Philippe.
^ permalink raw reply related [flat|nested] 7+ messages in thread
end of thread, other threads:[~2022-01-08 15:54 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-01-06 8:46 mm problems with 5.15.9-dovetail1 Jan Kiszka
2022-01-06 19:21 ` Philippe Gerum
2022-01-08 15:21 ` Philippe Gerum
2022-01-08 15:36 ` Philippe Gerum
2022-01-08 15:45 ` Philippe Gerum
2022-01-08 15:49 ` Philippe Gerum
2022-01-08 15:54 ` Philippe Gerum
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