[syzbot] upstream test error: BUG: sleeping function called from invalid context in stack_depot_save

[syzbot] upstream test error: BUG: sleeping function called from invalid context in stack_depot_save

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    dbe69e43 Merge tag 'net-next-5.14' of git://git.kernel.org..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1216d478300000
kernel config:  https://syzkaller.appspot.com/x/.config?x=47e4697be2f5b985
dashboard link: https://syzkaller.appspot.com/bug?extid=e45919db2eab5e837646

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+e45919db2eab5e837646@syzkaller.appspotmail.com

BUG: sleeping function called from invalid context at mm/page_alloc.c:5179
in_atomic(): 0, irqs_disabled(): 1, non_block: 0, pid: 8436, name: syz-fuzzer
INFO: lockdep is turned off.
irq event stamp: 0
hardirqs last  enabled at (0): [<0000000000000000>] 0x0
hardirqs last disabled at (0): [<ffffffff814406db>] copy_process+0x1e1b/0x74c0 kernel/fork.c:2061
softirqs last  enabled at (0): [<ffffffff8144071c>] copy_process+0x1e5c/0x74c0 kernel/fork.c:2065
softirqs last disabled at (0): [<0000000000000000>] 0x0
CPU: 1 PID: 8436 Comm: syz-fuzzer Tainted: G        W         5.13.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:79 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:96
 ___might_sleep.cold+0x1f1/0x237 kernel/sched/core.c:9153
 prepare_alloc_pages+0x3da/0x580 mm/page_alloc.c:5179
 __alloc_pages+0x12f/0x500 mm/page_alloc.c:5375
 alloc_pages+0x18c/0x2a0 mm/mempolicy.c:2272
 stack_depot_save+0x39d/0x4e0 lib/stackdepot.c:303
 save_stack+0x15e/0x1e0 mm/page_owner.c:120
 __set_page_owner+0x50/0x290 mm/page_owner.c:181
 prep_new_page mm/page_alloc.c:2445 [inline]
 __alloc_pages_bulk+0x8b9/0x1870 mm/page_alloc.c:5313
 alloc_pages_bulk_array_node include/linux/gfp.h:557 [inline]
 vm_area_alloc_pages mm/vmalloc.c:2775 [inline]
 __vmalloc_area_node mm/vmalloc.c:2845 [inline]
 __vmalloc_node_range+0x39d/0x960 mm/vmalloc.c:2947
 __vmalloc_node mm/vmalloc.c:2996 [inline]
 vzalloc+0x67/0x80 mm/vmalloc.c:3066
 n_tty_open+0x16/0x170 drivers/tty/n_tty.c:1914
 tty_ldisc_open+0x9b/0x110 drivers/tty/tty_ldisc.c:464
 tty_ldisc_setup+0x43/0x100 drivers/tty/tty_ldisc.c:781
 tty_init_dev.part.0+0x1f4/0x610 drivers/tty/tty_io.c:1461
 tty_init_dev include/linux/err.h:36 [inline]
 tty_open_by_driver drivers/tty/tty_io.c:2102 [inline]
 tty_open+0xb16/0x1000 drivers/tty/tty_io.c:2150
 chrdev_open+0x266/0x770 fs/char_dev.c:414
 do_dentry_open+0x4c8/0x11c0 fs/open.c:826
 do_open fs/namei.c:3361 [inline]
 path_openat+0x1c0e/0x27e0 fs/namei.c:3494
 do_filp_open+0x190/0x3d0 fs/namei.c:3521
 do_sys_openat2+0x16d/0x420 fs/open.c:1195
 do_sys_open fs/open.c:1211 [inline]
 __do_sys_openat fs/open.c:1227 [inline]
 __se_sys_openat fs/open.c:1222 [inline]
 __x64_sys_openat+0x13f/0x1f0 fs/open.c:1222
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x4af20a
Code: e8 3b 82 fb ff 48 8b 7c 24 10 48 8b 74 24 18 48 8b 54 24 20 4c 8b 54 24 28 4c 8b 44 24 30 4c 8b 4c 24 38 48 8b 44 24 08 0f 05 <48> 3d 01 f0 ff ff 76 20 48 c7 44 24 40 ff ff ff ff 48 c7 44 24 48
RSP: 002b:000000c0003293f8 EFLAGS: 00000216 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 000000c00001e800 RCX: 00000000004af20a
RDX: 0000000000000000 RSI: 000000c0001a5a50 RDI: ffffffffffffff9c
RBP: 000000c000329470 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000216 R12: 00000000000001a6
R13: 00000000000001a5 R14: 0000000000000200 R15: 000000c00029c280
can: request_module (can-proto-0) failed.
can: request_module (can-proto-0) failed.
can: request_module (can-proto-0) failed.


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

Re: [syzbot] upstream test error: BUG: sleeping function called from invalid context in stack_depot_save

[Dmitry Vyukov]

On Thu, Jul 1, 2021 at 1:00 PM syzbot
<syzbot+e45919db2eab5e837646@syzkaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit:    dbe69e43 Merge tag 'net-next-5.14' of git://git.kernel.org..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=1216d478300000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=47e4697be2f5b985
> dashboard link: https://syzkaller.appspot.com/bug?extid=e45919db2eab5e837646
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+e45919db2eab5e837646@syzkaller.appspotmail.com

+kasan-dev@ for for stack_depot_save warning

> BUG: sleeping function called from invalid context at mm/page_alloc.c:5179
> in_atomic(): 0, irqs_disabled(): 1, non_block: 0, pid: 8436, name: syz-fuzzer
> INFO: lockdep is turned off.
> irq event stamp: 0
> hardirqs last  enabled at (0): [<0000000000000000>] 0x0
> hardirqs last disabled at (0): [<ffffffff814406db>] copy_process+0x1e1b/0x74c0 kernel/fork.c:2061
> softirqs last  enabled at (0): [<ffffffff8144071c>] copy_process+0x1e5c/0x74c0 kernel/fork.c:2065
> softirqs last disabled at (0): [<0000000000000000>] 0x0
> CPU: 1 PID: 8436 Comm: syz-fuzzer Tainted: G        W         5.13.0-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> Call Trace:
>  __dump_stack lib/dump_stack.c:79 [inline]
>  dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:96
>  ___might_sleep.cold+0x1f1/0x237 kernel/sched/core.c:9153
>  prepare_alloc_pages+0x3da/0x580 mm/page_alloc.c:5179
>  __alloc_pages+0x12f/0x500 mm/page_alloc.c:5375
>  alloc_pages+0x18c/0x2a0 mm/mempolicy.c:2272
>  stack_depot_save+0x39d/0x4e0 lib/stackdepot.c:303
>  save_stack+0x15e/0x1e0 mm/page_owner.c:120
>  __set_page_owner+0x50/0x290 mm/page_owner.c:181
>  prep_new_page mm/page_alloc.c:2445 [inline]
>  __alloc_pages_bulk+0x8b9/0x1870 mm/page_alloc.c:5313
>  alloc_pages_bulk_array_node include/linux/gfp.h:557 [inline]
>  vm_area_alloc_pages mm/vmalloc.c:2775 [inline]
>  __vmalloc_area_node mm/vmalloc.c:2845 [inline]
>  __vmalloc_node_range+0x39d/0x960 mm/vmalloc.c:2947
>  __vmalloc_node mm/vmalloc.c:2996 [inline]
>  vzalloc+0x67/0x80 mm/vmalloc.c:3066
>  n_tty_open+0x16/0x170 drivers/tty/n_tty.c:1914
>  tty_ldisc_open+0x9b/0x110 drivers/tty/tty_ldisc.c:464
>  tty_ldisc_setup+0x43/0x100 drivers/tty/tty_ldisc.c:781
>  tty_init_dev.part.0+0x1f4/0x610 drivers/tty/tty_io.c:1461
>  tty_init_dev include/linux/err.h:36 [inline]
>  tty_open_by_driver drivers/tty/tty_io.c:2102 [inline]
>  tty_open+0xb16/0x1000 drivers/tty/tty_io.c:2150
>  chrdev_open+0x266/0x770 fs/char_dev.c:414
>  do_dentry_open+0x4c8/0x11c0 fs/open.c:826
>  do_open fs/namei.c:3361 [inline]
>  path_openat+0x1c0e/0x27e0 fs/namei.c:3494
>  do_filp_open+0x190/0x3d0 fs/namei.c:3521
>  do_sys_openat2+0x16d/0x420 fs/open.c:1195
>  do_sys_open fs/open.c:1211 [inline]
>  __do_sys_openat fs/open.c:1227 [inline]
>  __se_sys_openat fs/open.c:1222 [inline]
>  __x64_sys_openat+0x13f/0x1f0 fs/open.c:1222
>  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>  do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
>  entry_SYSCALL_64_after_hwframe+0x44/0xae
> RIP: 0033:0x4af20a
> Code: e8 3b 82 fb ff 48 8b 7c 24 10 48 8b 74 24 18 48 8b 54 24 20 4c 8b 54 24 28 4c 8b 44 24 30 4c 8b 4c 24 38 48 8b 44 24 08 0f 05 <48> 3d 01 f0 ff ff 76 20 48 c7 44 24 40 ff ff ff ff 48 c7 44 24 48
> RSP: 002b:000000c0003293f8 EFLAGS: 00000216 ORIG_RAX: 0000000000000101
> RAX: ffffffffffffffda RBX: 000000c00001e800 RCX: 00000000004af20a
> RDX: 0000000000000000 RSI: 000000c0001a5a50 RDI: ffffffffffffff9c
> RBP: 000000c000329470 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000216 R12: 00000000000001a6
> R13: 00000000000001a5 R14: 0000000000000200 R15: 000000c00029c280
> can: request_module (can-proto-0) failed.
> can: request_module (can-proto-0) failed.
> can: request_module (can-proto-0) failed.
>
>
> ---
> This report is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@googlegroups.com.
>
> syzbot will keep track of this issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

Re: [syzbot] upstream test error: BUG: sleeping function called from invalid context in stack_depot_save

[Hillf Danton]

On Thu, 1 Jul 2021 13:10:37 +0200 Dmitry Vyukov wrote:
>On Thu, Jul 1, 2021 at 1:00 PM syzbot wrote:
>>
>> Hello,
>>
>> syzbot found the following issue on:
>>
>> HEAD commit:    dbe69e43 Merge tag 'net-next-5.14' of git://git.kernel.org..
>> git tree:       upstream
>> console output: https://syzkaller.appspot.com/x/log.txt?x=1216d478300000
>> kernel config:  https://syzkaller.appspot.com/x/.config?x=47e4697be2f5b985
>> dashboard link: https://syzkaller.appspot.com/bug?extid=e45919db2eab5e837646
>>
>> IMPORTANT: if you fix the issue, please add the following tag to the commit:
>> Reported-by: syzbot+e45919db2eab5e837646@syzkaller.appspotmail.com
>
>+kasan-dev@ for for stack_depot_save warning
>
>> BUG: sleeping function called from invalid context at mm/page_alloc.c:5179
>> in_atomic(): 0, irqs_disabled(): 1, non_block: 0, pid: 8436, name: syz-fuzzer
>> INFO: lockdep is turned off.
>> irq event stamp: 0
>> hardirqs last  enabled at (0): [<0000000000000000>] 0x0
>> hardirqs last disabled at (0): [<ffffffff814406db>] copy_process+0x1e1b/0x74c0 kernel/fork.c:2061
>> softirqs last  enabled at (0): [<ffffffff8144071c>] copy_process+0x1e5c/0x74c0 kernel/fork.c:2065
>> softirqs last disabled at (0): [<0000000000000000>] 0x0
>> CPU: 1 PID: 8436 Comm: syz-fuzzer Tainted: G        W         5.13.0-syzkaller #0
>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
>> Call Trace:
>>  __dump_stack lib/dump_stack.c:79 [inline]
>>  dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:96
>>  ___might_sleep.cold+0x1f1/0x237 kernel/sched/core.c:9153
>>  prepare_alloc_pages+0x3da/0x580 mm/page_alloc.c:5179
>>  __alloc_pages+0x12f/0x500 mm/page_alloc.c:5375
>>  alloc_pages+0x18c/0x2a0 mm/mempolicy.c:2272
>>  stack_depot_save+0x39d/0x4e0 lib/stackdepot.c:303
>>  save_stack+0x15e/0x1e0 mm/page_owner.c:120
>>  __set_page_owner+0x50/0x290 mm/page_owner.c:181
>>  prep_new_page mm/page_alloc.c:2445 [inline]
>>  __alloc_pages_bulk+0x8b9/0x1870 mm/page_alloc.c:5313
>>  alloc_pages_bulk_array_node include/linux/gfp.h:557 [inline]
>>  vm_area_alloc_pages mm/vmalloc.c:2775 [inline]
>>  __vmalloc_area_node mm/vmalloc.c:2845 [inline]
>>  __vmalloc_node_range+0x39d/0x960 mm/vmalloc.c:2947
>>  __vmalloc_node mm/vmalloc.c:2996 [inline]
>>  vzalloc+0x67/0x80 mm/vmalloc.c:3066
>>  n_tty_open+0x16/0x170 drivers/tty/n_tty.c:1914
>>  tty_ldisc_open+0x9b/0x110 drivers/tty/tty_ldisc.c:464
>>  tty_ldisc_setup+0x43/0x100 drivers/tty/tty_ldisc.c:781
>>  tty_init_dev.part.0+0x1f4/0x610 drivers/tty/tty_io.c:1461
>>  tty_init_dev include/linux/err.h:36 [inline]
>>  tty_open_by_driver drivers/tty/tty_io.c:2102 [inline]
>>  tty_open+0xb16/0x1000 drivers/tty/tty_io.c:2150
>>  chrdev_open+0x266/0x770 fs/char_dev.c:414
>>  do_dentry_open+0x4c8/0x11c0 fs/open.c:826
>>  do_open fs/namei.c:3361 [inline]
>>  path_openat+0x1c0e/0x27e0 fs/namei.c:3494
>>  do_filp_open+0x190/0x3d0 fs/namei.c:3521
>>  do_sys_openat2+0x16d/0x420 fs/open.c:1195
>>  do_sys_open fs/open.c:1211 [inline]
>>  __do_sys_openat fs/open.c:1227 [inline]
>>  __se_sys_openat fs/open.c:1222 [inline]
>>  __x64_sys_openat+0x13f/0x1f0 fs/open.c:1222
>>  do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>>  do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
>>  entry_SYSCALL_64_after_hwframe+0x44/0xae

One of the quick fixes is move preparing new page out of the local lock (with
irq disabled) if it is difficult to add changes in saving stack.

+++ x/mm/page_alloc.c
@@ -5231,6 +5231,7 @@ unsigned long __alloc_pages_bulk(gfp_t g
 	gfp_t alloc_gfp;
 	unsigned int alloc_flags = ALLOC_WMARK_LOW;
 	int nr_populated = 0, nr_account = 0;
+	LIST_HEAD(head);
 
 	if (unlikely(nr_pages <= 0))
 		return 0;
@@ -5308,17 +5309,29 @@ unsigned long __alloc_pages_bulk(gfp_t g
 			break;
 		}
 		nr_account++;
-
-		prep_new_page(page, 0, gfp, 0);
-		if (page_list)
-			list_add(&page->lru, page_list);
-		else
-			page_array[nr_populated] = page;
+		list_add(&page->lru, &head);
 		nr_populated++;
 	}
 
 	local_unlock_irqrestore(&pagesets.lock, flags);
 
+	list_for_each_entry(page, &head, lru)
+		prep_new_page(page, 0, gfp, 0);
+
+	if (page_list)
+		list_splice(&head, page_list);
+	else {
+		int i; 
+
+		for (i = 0; i < nr_pages && !list_empty(&head); i++) {
+			/* Skip existing pages */
+			if (page_array[i])
+				continue;
+			page = list_first_entry(&head, struct page, lru);
+			list_del_init(&page->lru);
+			page_array[i] = page;
+		}
+	}
 	__count_zid_vm_events(PGALLOC, zone_idx(zone), nr_account);
 	zone_statistics(ac.preferred_zoneref->zone, zone, nr_account);
 

Re: [syzbot] upstream test error: BUG: sleeping function called from invalid context in stack_depot_save

[Desmond Cheong Zhi Xi]

On 3/7/21 12:12 pm, Hillf Danton wrote:
> On Thu, 1 Jul 2021 13:10:37 +0200 Dmitry Vyukov wrote:
>> On Thu, Jul 1, 2021 at 1:00 PM syzbot wrote:
>>>
>>> Hello,
>>>
>>> syzbot found the following issue on:
>>>
>>> HEAD commit:    dbe69e43 Merge tag 'net-next-5.14' of git://git.kernel.org..
>>> git tree:       upstream
>>> console output: https://syzkaller.appspot.com/x/log.txt?x=1216d478300000
>>> kernel config:  https://syzkaller.appspot.com/x/.config?x=47e4697be2f5b985
>>> dashboard link: https://syzkaller.appspot.com/bug?extid=e45919db2eab5e837646
>>>
>>> IMPORTANT: if you fix the issue, please add the following tag to the commit:
>>> Reported-by: syzbot+e45919db2eab5e837646@syzkaller.appspotmail.com
>>
>> +kasan-dev@ for for stack_depot_save warning
>>
>>> BUG: sleeping function called from invalid context at mm/page_alloc.c:5179
>>> in_atomic(): 0, irqs_disabled(): 1, non_block: 0, pid: 8436, name: syz-fuzzer
>>> INFO: lockdep is turned off.
>>> irq event stamp: 0
>>> hardirqs last  enabled at (0): [<0000000000000000>] 0x0
>>> hardirqs last disabled at (0): [<ffffffff814406db>] copy_process+0x1e1b/0x74c0 kernel/fork.c:2061
>>> softirqs last  enabled at (0): [<ffffffff8144071c>] copy_process+0x1e5c/0x74c0 kernel/fork.c:2065
>>> softirqs last disabled at (0): [<0000000000000000>] 0x0
>>> CPU: 1 PID: 8436 Comm: syz-fuzzer Tainted: G        W         5.13.0-syzkaller #0
>>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
>>> Call Trace:
>>>   __dump_stack lib/dump_stack.c:79 [inline]
>>>   dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:96
>>>   ___might_sleep.cold+0x1f1/0x237 kernel/sched/core.c:9153
>>>   prepare_alloc_pages+0x3da/0x580 mm/page_alloc.c:5179
>>>   __alloc_pages+0x12f/0x500 mm/page_alloc.c:5375
>>>   alloc_pages+0x18c/0x2a0 mm/mempolicy.c:2272
>>>   stack_depot_save+0x39d/0x4e0 lib/stackdepot.c:303
>>>   save_stack+0x15e/0x1e0 mm/page_owner.c:120
>>>   __set_page_owner+0x50/0x290 mm/page_owner.c:181
>>>   prep_new_page mm/page_alloc.c:2445 [inline]
>>>   __alloc_pages_bulk+0x8b9/0x1870 mm/page_alloc.c:5313
>>>   alloc_pages_bulk_array_node include/linux/gfp.h:557 [inline]
>>>   vm_area_alloc_pages mm/vmalloc.c:2775 [inline]
>>>   __vmalloc_area_node mm/vmalloc.c:2845 [inline]
>>>   __vmalloc_node_range+0x39d/0x960 mm/vmalloc.c:2947
>>>   __vmalloc_node mm/vmalloc.c:2996 [inline]
>>>   vzalloc+0x67/0x80 mm/vmalloc.c:3066
>>>   n_tty_open+0x16/0x170 drivers/tty/n_tty.c:1914
>>>   tty_ldisc_open+0x9b/0x110 drivers/tty/tty_ldisc.c:464
>>>   tty_ldisc_setup+0x43/0x100 drivers/tty/tty_ldisc.c:781
>>>   tty_init_dev.part.0+0x1f4/0x610 drivers/tty/tty_io.c:1461
>>>   tty_init_dev include/linux/err.h:36 [inline]
>>>   tty_open_by_driver drivers/tty/tty_io.c:2102 [inline]
>>>   tty_open+0xb16/0x1000 drivers/tty/tty_io.c:2150
>>>   chrdev_open+0x266/0x770 fs/char_dev.c:414
>>>   do_dentry_open+0x4c8/0x11c0 fs/open.c:826
>>>   do_open fs/namei.c:3361 [inline]
>>>   path_openat+0x1c0e/0x27e0 fs/namei.c:3494
>>>   do_filp_open+0x190/0x3d0 fs/namei.c:3521
>>>   do_sys_openat2+0x16d/0x420 fs/open.c:1195
>>>   do_sys_open fs/open.c:1211 [inline]
>>>   __do_sys_openat fs/open.c:1227 [inline]
>>>   __se_sys_openat fs/open.c:1222 [inline]
>>>   __x64_sys_openat+0x13f/0x1f0 fs/open.c:1222
>>>   do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>>>   do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
>>>   entry_SYSCALL_64_after_hwframe+0x44/0xae
> 
> One of the quick fixes is move preparing new page out of the local lock (with
> irq disabled) if it is difficult to add changes in saving stack.
> 
> +++ x/mm/page_alloc.c
> @@ -5231,6 +5231,7 @@ unsigned long __alloc_pages_bulk(gfp_t g
>   	gfp_t alloc_gfp;
>   	unsigned int alloc_flags = ALLOC_WMARK_LOW;
>   	int nr_populated = 0, nr_account = 0;
> +	LIST_HEAD(head);
>   
>   	if (unlikely(nr_pages <= 0))
>   		return 0;
> @@ -5308,17 +5309,29 @@ unsigned long __alloc_pages_bulk(gfp_t g
>   			break;
>   		}
>   		nr_account++;
> -
> -		prep_new_page(page, 0, gfp, 0);
> -		if (page_list)
> -			list_add(&page->lru, page_list);
> -		else
> -			page_array[nr_populated] = page;
> +		list_add(&page->lru, &head);
>   		nr_populated++;
>   	}
>   
>   	local_unlock_irqrestore(&pagesets.lock, flags);
>   
> +	list_for_each_entry(page, &head, lru)
> +		prep_new_page(page, 0, gfp, 0);
> +
> +	if (page_list)
> +		list_splice(&head, page_list);
> +	else {
> +		int i;
> +
> +		for (i = 0; i < nr_pages && !list_empty(&head); i++) {
> +			/* Skip existing pages */
> +			if (page_array[i])
> +				continue;
> +			page = list_first_entry(&head, struct page, lru);
> +			list_del_init(&page->lru);
> +			page_array[i] = page;
> +		}
> +	}
>   	__count_zid_vm_events(PGALLOC, zone_idx(zone), nr_account);
>   	zone_statistics(ac.preferred_zoneref->zone, zone, nr_account);
>   
> 

I believe this particular bug should be fixed by Mel Gorman's patch that 
was added into Andrew Morton's -mm tree (mm/page_alloc: Avoid page 
allocator recursion with pagesets.lock held):
https://lore.kernel.org/lkml/20210708081434.GV3840@techsingularity.net/

With the patch, we avoid recursing into stack_depot_save while holding 
onto the local lock.

Best wishes,
Desmond

Re: [syzbot] upstream test error: BUG: sleeping function called from invalid context in stack_depot_save

[Hillf Danton]

On Tue, 13 Jul 2021 17:51:19 +0800 Desmond Cheong Zhi Xi wrote:
>
>I believe this particular bug should be fixed by Mel Gorman's patch that 
>was added into Andrew Morton's -mm tree (mm/page_alloc: Avoid page 
>allocator recursion with pagesets.lock held):
>https://lore.kernel.org/lkml/20210708081434.GV3840@techsingularity.net/
>
>With the patch, we avoid recursing into stack_depot_save while holding 
>onto the local lock.

You are right. Different fixes of different tastes.

Thanks for taking a look at it.

Hillf

Re: [syzbot] upstream test error: BUG: sleeping function called from invalid context in stack_depot_save

[syzbot]

This bug is marked as fixed by commit:
187ad460b841 ("mm/page_alloc: avoid page allocator recursion with pagesets.lock held")
But I can't find it in any tested tree for more than 90 days.
Is it a correct commit? Please update it by replying:
#syz fix: exact-commit-title
Until then the bug is still considered open and
new crashes with the same signature are ignored.

Re: [syzbot] upstream test error: BUG: sleeping function called from invalid context in stack_depot_save

[Marco Elver]

#syz fix: mm/page_alloc: avoid page allocator recursion with pagesets.lock held

On Tue, 26 Oct 2021 at 16:08, syzbot
<syzbot+e45919db2eab5e837646@syzkaller.appspotmail.com> wrote:
>
> This bug is marked as fixed by commit:
> 187ad460b841 ("mm/page_alloc: avoid page allocator recursion with pagesets.lock held")

Looks like Dan's "#syz fix" made syzbot think that the title is the above.

The reason that the commit title only is preferred is that commits in
trees like -mm don't have stable hashes. Maybe if the hash is known to
persist the alternative format could be useful.