From: Jan Beulich <jbeulich@suse.com>
To: Igor Druzhinin <igor.druzhinin@citrix.com>
Cc: xen-devel@lists.xen.org, boris.ostrovsky@oracle.com,
stephen.s.brennan@oracle.com, roger.pau@citrix.com
Subject: Re: BUG in 1f3d87c75129 ("x86/vpt: do not take pt_migrate rwlock in some cases")
Date: Mon, 14 Jun 2021 13:53:09 +0200 [thread overview]
Message-ID: <74378af9-5d04-f95e-3957-918cf5c81ded@suse.com> (raw)
In-Reply-To: <0efd0099-49bb-e20c-fe8d-fb97c9de2b63@citrix.com>
On 14.06.2021 13:15, Igor Druzhinin wrote:
> Hi, Boris, Stephen, Roger,
>
> We have stress tested recent changes on staging-4.13 which includes a
> backport of the subject. Since the backport is identical to the
> master branch and all of the pre-reqs are in place - we have no reason
> to believe the issue is not the same on master.
>
> Here is what we got by running heavy stress testing including multiple
> repeated VM lifecycle operations with storage and network load:
>
>
> Assertion 'timer->status >= TIMER_STATUS_inactive' failed at timer.c:287
> ----[ Xen-4.13.3-10.7-d x86_64 debug=y Not tainted ]----
> CPU: 17
> RIP: e008:[<ffff82d080246b65>] common/timer.c#active_timer+0xc/0x1b
> RFLAGS: 0000000000010046 CONTEXT: hypervisor (d675v0)
> rax: 0000000000000000 rbx: ffff83137a8ed300 rcx: 0000000000000000
> rdx: ffff83303fff7fff rsi: ffff83303fff2549 rdi: ffff83137a8ed300
> rbp: ffff83303fff7cf8 rsp: ffff83303fff7cf8 r8: 0000000000000001
> r9: 0000000000000000 r10: 0000000000000011 r11: 0000168b0cc08083
> r12: 0000000000000000 r13: ffff82d0805cf300 r14: ffff82d0805cf300
> r15: 0000000000000292 cr0: 0000000080050033 cr4: 00000000000426e0
> cr3: 00000013c1a32000 cr2: 0000000000000000
> fsb: 0000000000000000 gsb: 0000000000000000 gss: 0000000000000000
> ds: 0000 es: 0000 fs: 0000 gs: 0000 ss: 0000 cs: e008
> Xen code around <ffff82d080246b65> (common/timer.c#active_timer+0xc/0x1b):
> 0f b6 47 2a 84 c0 75 02 <0f> 0b 3c 04 76 02 0f 0b 3c 02 0f 97 c0 5d c3 55
> Xen stack trace from rsp=ffff83303fff7cf8:
> ffff83303fff7d48 ffff82d0802479f1 0000168b0192b846 ffff83137a8ed328
> 000000001d0776eb ffff83137a8ed2c0 ffff83133ee47568 ffff83133ee47000
> ffff83133ee47560 ffff832b1a0cd000 ffff83303fff7d78 ffff82d08031e74e
> ffff83102d898000 ffff83133ee47000 ffff83102db8d000 0000000000000011
> ffff83303fff7dc8 ffff82d08027df19 0000000000000000 ffff83133ee47060
> ffff82d0805d0088 ffff83102d898000 ffff83133ee47000 0000000000000011
> 0000000000000001 0000000000000011 ffff83303fff7e08 ffff82d0802414e0
> ffff83303fff7df8 0000168b0192b846 ffff83102d8a4660 0000168b0192b846
> ffff83102d8a4720 0000000000000011 ffff83303fff7ea8 ffff82d080241d6c
> ffff83133ee47000 ffff831244137a50 ffff83303fff7e48 ffff82d08031b5b8
> ffff83133ee47000 ffff832b1a0cd000 ffff83303fff7e68 ffff82d080312b65
> ffff83133ee47000 0000000000000000 ffff83303fff7ee8 ffff83102d8a4678
> ffff83303fff7ee8 ffff82d0805d6380 ffff82d0805d5b00 ffffffffffffffff
> ffff83303fff7fff 0000000000000000 ffff83303fff7ed8 ffff82d0802431f5
> ffff83133ee47000 0000000000000000 0000000000000000 0000000000000000
> ffff83303fff7ee8 ffff82d08024324a 00007ccfc00080e7 ffff82d08033930b
> ffffffffb0ebd5a0 000000000000000d 0000000000000062 0000000000000097
> 000000000000001e 000000000000001f ffffffffb0ebd5ad 0000000000000000
> 0000000000000005 000000000003d91d 0000000000000000 0000000000000000
> 00000000000003d5 000000000000001e 0000000000000000 0000beef0000beef
> Xen call trace:
> [<ffff82d080246b65>] R common/timer.c#active_timer+0xc/0x1b
> [<ffff82d0802479f1>] F stop_timer+0xf5/0x188
> [<ffff82d08031e74e>] F pt_save_timer+0x45/0x8a
> [<ffff82d08027df19>] F context_switch+0xf9/0xee0
> [<ffff82d0802414e0>] F common/schedule.c#sched_context_switch+0x146/0x151
> [<ffff82d080241d6c>] F common/schedule.c#schedule+0x28a/0x299
> [<ffff82d0802431f5>] F common/softirq.c#__do_softirq+0x85/0x90
> [<ffff82d08024324a>] F do_softirq+0x13/0x15
> [<ffff82d08033930b>] F vmx_asm_do_vmentry+0x2b/0x30
>
> ****************************************
> Panic on CPU 17:
> Assertion 'timer->status >= TIMER_STATUS_inactive' failed at timer.c:287
> ****************************************
Since this suggests a timer was found on the list without ever having been
initialized, I've spotted a case where this indeed could now happen. Could
you give the patch below a try?
Jan
x86/vpt: fully init timers before putting onto list
With pt_vcpu_lock() no longer acquiring the pt_migrate lock, parties
iterating the list and acting on the timers of the list entries will no
longer be kept from entering their loops by create_periodic_time()'s
holding of that lock. Therefore at least init_timer() needs calling
ahead of list insertion, but keep this and set_timer() together.
Fixes: 8113b02f0bf8 ("x86/vpt: do not take pt_migrate rwlock in some cases")
Reported-by: Igor Druzhinin <igor.druzhinin@citrix.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
--- unstable.orig/xen/arch/x86/hvm/vpt.c
+++ unstable/xen/arch/x86/hvm/vpt.c
@@ -554,14 +554,14 @@ void create_periodic_time(
pt->cb = cb;
pt->priv = data;
+ init_timer(&pt->timer, pt_timer_fn, pt, v->processor);
+ set_timer(&pt->timer, pt->scheduled);
+
pt_vcpu_lock(v);
pt->on_list = 1;
list_add(&pt->list, &v->arch.hvm.tm_list);
pt_vcpu_unlock(v);
- init_timer(&pt->timer, pt_timer_fn, pt, v->processor);
- set_timer(&pt->timer, pt->scheduled);
-
write_unlock(&v->domain->arch.hvm.pl_time->pt_migrate);
}
next prev parent reply other threads:[~2021-06-14 11:53 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-14 11:15 BUG in 1f3d87c75129 ("x86/vpt: do not take pt_migrate rwlock in some cases") Igor Druzhinin
2021-06-14 11:53 ` Jan Beulich [this message]
2021-06-14 13:27 ` Roger Pau Monné
2021-06-14 16:01 ` Jan Beulich
2021-06-14 16:10 ` Andrew Cooper
2021-06-14 17:06 ` Boris Ostrovsky
2021-06-15 8:12 ` Roger Pau Monné
2021-06-15 9:17 ` Andrew Cooper
2021-06-15 13:17 ` Jan Beulich
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=74378af9-5d04-f95e-3957-918cf5c81ded@suse.com \
--to=jbeulich@suse.com \
--cc=boris.ostrovsky@oracle.com \
--cc=igor.druzhinin@citrix.com \
--cc=roger.pau@citrix.com \
--cc=stephen.s.brennan@oracle.com \
--cc=xen-devel@lists.xen.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).