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From: Fabian Ebner <f.ebner@proxmox.com>
To: pve-devel@lists.proxmox.com
Date: Thu, 9 Jun 2022 14:31:13 +0200
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Subject: [pve-devel] [PATCH v2 qemu] fix #4101: acquire job's aio context
before calling job_unref
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Otherwise, we might run into an abort via bdrv_co_yield_to_drain()
(can at least happen when a disk with iothread is used):
> #0 0x00007fef4f5dece1 __GI_raise (libc.so.6 + 0x3bce1)
> #1 0x00007fef4f5c8537 __GI_abort (libc.so.6 + 0x25537)
> #2 0x00005641bce3c71f error_exit (qemu-system-x86_64 + 0x80371f)
> #3 0x00005641bce3d02b qemu_mutex_unlock_impl (qemu-system-x86_64 + 0x80402b)
> #4 0x00005641bcd51655 bdrv_co_yield_to_drain (qemu-system-x86_64 + 0x718655)
> #5 0x00005641bcd52de8 bdrv_do_drained_begin (qemu-system-x86_64 + 0x719de8)
> #6 0x00005641bcd47e07 blk_drain (qemu-system-x86_64 + 0x70ee07)
> #7 0x00005641bcd498cd blk_unref (qemu-system-x86_64 + 0x7108cd)
> #8 0x00005641bcd31e6f block_job_free (qemu-system-x86_64 + 0x6f8e6f)
> #9 0x00005641bcd32d65 job_unref (qemu-system-x86_64 + 0x6f9d65)
> #10 0x00005641bcd93b3d pvebackup_co_complete_stream (qemu-system-x86_64 + 0x75ab3d)
> #11 0x00005641bce4e353 coroutine_trampoline (qemu-system-x86_64 + 0x815353)
Signed-off-by: Fabian Ebner <f.ebner@proxmox.com>
---
Changes from v1:
* Fix commit message.
* Do di->job = NULL before releasing the context.
* Also keep context before job_ref.
* Avoid temporarily releasing/re-acquiring aio context in error
scenario.
Sent as a direct patch for reviewability. Intended to be squashed into
0055-PVE-Backup-ensure-jobs-in-di_list-are-referenced.patch
pve-backup.c | 20 +++++++++++---------
1 file changed, 11 insertions(+), 9 deletions(-)
diff --git a/pve-backup.c b/pve-backup.c
index be21027dad..2e22030eec 100644
--- a/pve-backup.c
+++ b/pve-backup.c
@@ -317,8 +317,11 @@ static void coroutine_fn pvebackup_co_complete_stream(void *opaque)
}
if (di->job) {
+ AioContext *ctx = di->job->job.aio_context;
+ aio_context_acquire(ctx);
job_unref(&di->job->job);
di->job = NULL;
+ aio_context_release(ctx);
}
// remove self from job list
@@ -513,13 +516,13 @@ static void create_backup_jobs_bh(void *opaque) {
bitmap_mode, false, NULL, &perf, BLOCKDEV_ON_ERROR_REPORT, BLOCKDEV_ON_ERROR_REPORT,
JOB_DEFAULT, pvebackup_complete_cb, di, backup_state.txn, &local_err);
- aio_context_release(aio_context);
-
di->job = job;
if (job) {
job_ref(&job->job);
}
+ aio_context_release(aio_context);
+
if (!job || local_err) {
error_setg(errp, "backup_job_create failed: %s",
local_err ? error_get_pretty(local_err) : "null");
@@ -546,17 +549,16 @@ static void create_backup_jobs_bh(void *opaque) {
di->target = NULL;
}
- if (!canceled && di->job) {
+ if (di->job) {
AioContext *ctx = di->job->job.aio_context;
aio_context_acquire(ctx);
- job_cancel_sync(&di->job->job, true);
- aio_context_release(ctx);
- canceled = true;
- }
-
- if (di->job) {
+ if (!canceled) {
+ job_cancel_sync(&di->job->job, true);
+ canceled = true;
+ }
job_unref(&di->job->job);
di->job = NULL;
+ aio_context_release(ctx);
}
}
}
--
2.30.2