Re: linux-next boot error: WARNING in prepare_kswapd_sleep
On Wed, 25 Nov 2020 at 06:25, Alex Shi wrote: > Acked. Thanks. I submitted as an actual patch, refactored it slightly to avoid duplication of page_memcg(). > and further more, could you like try another patch? I tried that patch against the syzkaller failure case and it worked fine! Cheers, Lorenzo
Re: linux-next boot error: WARNING in prepare_kswapd_sleep
在 2020/11/25 上午1:59, Lorenzo Stoakes 写道:
> On Tue, 24 Nov 2020 at 07:54, syzbot
> wrote:
>> syzbot found the following issue on:
>>
>> HEAD commit:d9137320 Add linux-next specific files for 20201124
>
> This appears to be a product of 4b2904f3 ("mm/memcg: add missed
> warning in mem_cgroup_lruvec") adding a VM_WARN_ON_ONCE() to
> mem_cgroup_lruvec, which when invoked from a function other than
> mem_cgroup_page_lruvec() can in fact be called with the condition
> false.
> If we move the check back into mem_cgroup_page_lruvec() it resolves
> the issue. I enclose a simple version of this below, happy to submit
> as a proper patch if this is the right approach:
>
>
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index 87ed56dc75f9..27cc40a490b2 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -618,7 +618,6 @@ static inline struct lruvec
> *mem_cgroup_lruvec(struct mem_cgroup *memcg,
> goto out;
> }
>
> - VM_WARN_ON_ONCE(!memcg);
> if (!memcg)
> memcg = root_mem_cgroup;
>
> @@ -645,6 +644,7 @@ static inline struct lruvec
> *mem_cgroup_lruvec(struct mem_cgroup *memcg,
> static inline struct lruvec *mem_cgroup_page_lruvec(struct page *page,
> struct pglist_data *pgdat)
> {
> + VM_WARN_ON_ONCE_PAGE(!page_memcg(page), page);
> return mem_cgroup_lruvec(page_memcg(page), pgdat);
> }
>
Acked.
Right. Would you like to remove the bad commit 4b2904f3 ("mm/memcg: add missed
warning in mem_cgroup_lruvec") and replace yours.
and further more, could you like try another patch?
Thanks
Alex
>From 073b222bd06a96c39656b0460c705e48c7eedafc Mon Sep 17 00:00:00 2001
From: Alex Shi
Date: Wed, 25 Nov 2020 14:06:33 +0800
Subject: [PATCH] mm/memcg: bail out early when !memcg in mem_cgroup_lruvec
In some scenarios, we call NULL memcg in mem_cgroup_lruvec(NULL, pgdat)
so we could get out early to skip unnecessary check.
Also warning if both parameter are NULL.
Signed-off-by: Alex Shi
---
include/linux/memcontrol.h | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 3a995bb3157f..5e4da83eb9ce 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -613,7 +613,9 @@ static inline struct lruvec *mem_cgroup_lruvec(struct
mem_cgroup *memcg,
struct mem_cgroup_per_node *mz;
struct lruvec *lruvec;
- if (mem_cgroup_disabled()) {
+ VM_WARN_ON_ONCE(!memcg && !pgdat);
+
+ if (mem_cgroup_disabled() || !memcg) {
lruvec = >__lruvec;
goto out;
}
--
2.29.GIT
Re: linux-next boot error: WARNING in prepare_kswapd_sleep
On Tue, 24 Nov 2020 at 07:54, syzbot
wrote:
> syzbot found the following issue on:
>
> HEAD commit:d9137320 Add linux-next specific files for 20201124
This appears to be a product of 4b2904f3 ("mm/memcg: add missed
warning in mem_cgroup_lruvec") adding a VM_WARN_ON_ONCE() to
mem_cgroup_lruvec, which when invoked from a function other than
mem_cgroup_page_lruvec() can in fact be called with the condition
false.
If we move the check back into mem_cgroup_page_lruvec() it resolves
the issue. I enclose a simple version of this below, happy to submit
as a proper patch if this is the right approach:
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 87ed56dc75f9..27cc40a490b2 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -618,7 +618,6 @@ static inline struct lruvec
*mem_cgroup_lruvec(struct mem_cgroup *memcg,
goto out;
}
- VM_WARN_ON_ONCE(!memcg);
if (!memcg)
memcg = root_mem_cgroup;
@@ -645,6 +644,7 @@ static inline struct lruvec
*mem_cgroup_lruvec(struct mem_cgroup *memcg,
static inline struct lruvec *mem_cgroup_page_lruvec(struct page *page,
struct pglist_data *pgdat)
{
+ VM_WARN_ON_ONCE_PAGE(!page_memcg(page), page);
return mem_cgroup_lruvec(page_memcg(page), pgdat);
}
linux-next boot error: WARNING in prepare_kswapd_sleep
Hello, syzbot found the following issue on: HEAD commit:d9137320 Add linux-next specific files for 20201124 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=17b1407950 kernel config: https://syzkaller.appspot.com/x/.config?x=2ac6081150c8eac dashboard link: https://syzkaller.appspot.com/bug?extid=ce635500093181f39c1c compiler: gcc (GCC) 10.1.0-syz 20200507 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+ce635500093181f39...@syzkaller.appspotmail.com [ cut here ] WARNING: CPU: 1 PID: 2192 at include/linux/memcontrol.h:621 arch_static_branch arch/x86/include/asm/jump_label.h:25 [inline] WARNING: CPU: 1 PID: 2192 at include/linux/memcontrol.h:621 mem_cgroup_disabled include/linux/memcontrol.h:504 [inline] WARNING: CPU: 1 PID: 2192 at include/linux/memcontrol.h:621 mem_cgroup_lruvec include/linux/memcontrol.h:616 [inline] WARNING: CPU: 1 PID: 2192 at include/linux/memcontrol.h:621 clear_pgdat_congested mm/vmscan.c:3443 [inline] WARNING: CPU: 1 PID: 2192 at include/linux/memcontrol.h:621 prepare_kswapd_sleep mm/vmscan.c:3480 [inline] WARNING: CPU: 1 PID: 2192 at include/linux/memcontrol.h:621 prepare_kswapd_sleep+0xed/0x250 mm/vmscan.c:3456 Modules linked in: CPU: 1 PID: 2192 Comm: kswapd0 Not tainted 5.10.0-rc5-next-20201124-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:mem_cgroup_lruvec include/linux/memcontrol.h:621 [inline] RIP: 0010:clear_pgdat_congested mm/vmscan.c:3443 [inline] RIP: 0010:prepare_kswapd_sleep mm/vmscan.c:3480 [inline] RIP: 0010:prepare_kswapd_sleep+0xed/0x250 mm/vmscan.c:3456 Code: 89 ee 48 89 df e8 73 d3 ff ff 31 ff 41 89 c4 89 c6 e8 87 19 d7 ff 45 84 e4 74 cc e8 6d 21 d7 ff 0f 1f 44 00 00 e8 63 21 d7 ff <0f> 0b 48 c7 c0 28 8d ee 8c 48 ba 00 00 00 00 00 fc ff df 48 c1 e8 RSP: :c900085bfda0 EFLAGS: 00010293 RAX: RBX: 88813fffb000 RCX: 81998e19 RDX: 8880168c1ac0 RSI: 81998e2d RDI: 0001 RBP: R08: 0ab3 R09: 0f89 R10: R11: R12: 0001 R13: 0004 R14: R15: 0003 FS: () GS:8880b9f0() knlGS: CS: 0010 DS: ES: CR0: 80050033 CR2: CR3: 0b08e000 CR4: 001506e0 DR0: DR1: DR2: DR3: DR6: fffe0ff0 DR7: 0400 Call Trace: kswapd_try_to_sleep mm/vmscan.c:3784 [inline] kswapd+0x37d/0xdb0 mm/vmscan.c:3899 kthread+0x3b1/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296 Kernel panic - not syncing: panic_on_warn set ... CPU: 1 PID: 2192 Comm: kswapd0 Not tainted 5.10.0-rc5-next-20201124-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+0x107/0x163 lib/dump_stack.c:120 panic+0x306/0x73d kernel/panic.c:231 __warn.cold+0x35/0x44 kernel/panic.c:605 report_bug+0x1bd/0x210 lib/bug.c:198 handle_bug+0x3c/0x60 arch/x86/kernel/traps.c:239 exc_invalid_op+0x14/0x40 arch/x86/kernel/traps.c:259 asm_exc_invalid_op+0x12/0x20 arch/x86/include/asm/idtentry.h:578 RIP: 0010:mem_cgroup_lruvec include/linux/memcontrol.h:621 [inline] RIP: 0010:clear_pgdat_congested mm/vmscan.c:3443 [inline] RIP: 0010:prepare_kswapd_sleep mm/vmscan.c:3480 [inline] RIP: 0010:prepare_kswapd_sleep+0xed/0x250 mm/vmscan.c:3456 Code: 89 ee 48 89 df e8 73 d3 ff ff 31 ff 41 89 c4 89 c6 e8 87 19 d7 ff 45 84 e4 74 cc e8 6d 21 d7 ff 0f 1f 44 00 00 e8 63 21 d7 ff <0f> 0b 48 c7 c0 28 8d ee 8c 48 ba 00 00 00 00 00 fc ff df 48 c1 e8 RSP: :c900085bfda0 EFLAGS: 00010293 RAX: RBX: 88813fffb000 RCX: 81998e19 RDX: 8880168c1ac0 RSI: 81998e2d RDI: 0001 RBP: R08: 0ab3 R09: 0f89 R10: R11: R12: 0001 R13: 0004 R14: R15: 0003 kswapd_try_to_sleep mm/vmscan.c:3784 [inline] kswapd+0x37d/0xdb0 mm/vmscan.c:3899 kthread+0x3b1/0x4a0 kernel/kthread.c:292 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296 Kernel Offset: disabled Rebooting in 86400 seconds.. --- 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 syzkal...@googlegroups.com. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
