[Hyper-V] Crash in hot-add/remove scsi devices (smp)
| Affects | Status | Importance | Assigned to | Milestone | |
|---|---|---|---|---|---|
| linux (Ubuntu) |
Fix Released
|
Medium
|
Joseph Salisbury | ||
| Trusty |
Fix Released
|
Medium
|
Joseph Salisbury | ||
| Vivid |
Fix Released
|
Medium
|
Joseph Salisbury | ||
| Wily |
Fix Released
|
Medium
|
Joseph Salisbury | ||
| Xenial |
Fix Released
|
Medium
|
Joseph Salisbury | ||
Bug Description
On some host errors storvsc module tries to remove sdev by scheduling a job
which does the following:
sdev = scsi_device_
if (sdev) {
}
While this code seems correct the following crash is observed:
general protection fault: 0000 [#1] SMP DEBUG_PAGEALLOC
RIP: 0010:[<
...
[<ffffffff814a
[<ffffffff8127
[<ffffffffa00b
[<ffffffffa00b
[<ffffffffa00e
[<ffffffff8108
...
The problem comes with the fact that many such jobs (for the same device)
are being scheduled simultaneously. While scsi_remove_
shost->scan_mutex and scsi_device_
SDEV_DEL state there is no protection against someone who did
scsi_device_
the whole scenario looks like that: two callers do simultaneous (or
preemption happens) calls to scsi_device_
for all of them, after that both callers try doing scsi_remove_
shost->scan_mutex only serializes their calls to __scsi_
and we end up doing the cleanup path twice.
Signed-off-by: Vitaly Kuznetsov <email address hidden>
---
drivers/
1 file changed, 8 insertions(+)
diff --git a/drivers/
index b333389..e0d2707 100644
--- a/drivers/
+++ b/drivers/
@@ -1076,6 +1076,14 @@ void __scsi_
{
struct device *dev = &sdev->sdev_gendev;
+ /*
+ * This cleanup path is not reentrant and while it is impossible
+ * to get a new reference with scsi_device_get() someone can still
+ * hold a previously acquired one.
+ */
+ if (sdev->sdev_state == SDEV_DEL)
+ return;
+
if (sdev->is_visible) {
if (scsi_device_
--
2.4.3
| tags: | added: kernel-da-key kernel-hyper-v |
| Changed in linux (Ubuntu): | |
| status: | New → Confirmed |
| Changed in linux (Ubuntu): | |
| importance: | Undecided → Medium |
| Joseph Salisbury (jsalisbury) wrote | #1 |
| Changed in linux (Ubuntu): | |
| assignee: | nobody → Joseph Salisbury (jsalisbury) |
| Joshua R. Poulson (jrp) wrote | #2 |
| Joseph Salisbury (jsalisbury) wrote | #3 |
| Joseph Salisbury (jsalisbury) wrote | #4 |
| Changed in linux (Ubuntu Wily): | |
| importance: | Undecided → Medium |
| status: | New → In Progress |
| Changed in linux (Ubuntu): | |
| status: | Confirmed → In Progress |
| Changed in linux (Ubuntu Wily): | |
| assignee: | nobody → Joseph Salisbury (jsalisbury) |
| Chris Valean (cvalean) wrote | #5 |
| Changed in linux (Ubuntu Vivid): | |
| status: | New → In Progress |
| Changed in linux (Ubuntu Trusty): | |
| status: | New → In Progress |
| importance: | Undecided → Medium |
| Changed in linux (Ubuntu Vivid): | |
| importance: | Undecided → Medium |
| assignee: | nobody → Joseph Salisbury (jsalisbury) |
| Changed in linux (Ubuntu Trusty): | |
| assignee: | nobody → Joseph Salisbury (jsalisbury) |
| Joseph Salisbury (jsalisbury) wrote | #6 |
| Adrian Suhov (asuhov) wrote | #7 |
| Changed in linux (Ubuntu Trusty): | |
| status: | In Progress → Fix Committed |
| Changed in linux (Ubuntu Vivid): | |
| status: | In Progress → Fix Committed |
| Changed in linux (Ubuntu Wily): | |
| status: | In Progress → Fix Committed |
| Changed in linux (Ubuntu Xenial): | |
| status: | In Progress → Fix Committed |
| Launchpad Janitor (janitor) wrote | #8 |
| Changed in linux (Ubuntu Xenial): | |
| status: | Fix Committed → Fix Released |
| Brad Figg (brad-figg) wrote | #9 |
| tags: | added: verification-needed-trusty |
| tags: | added: verification-needed-vivid |
| Brad Figg (brad-figg) wrote | #10 |
| tags: | added: verification-needed-wily |
| Brad Figg (brad-figg) wrote | #11 |
| Joshua R. Poulson (jrp) wrote | #12 |
| Joseph Salisbury (jsalisbury) wrote | #13 |
| Joshua R. Poulson (jrp) wrote | #14 |
| tags: |
added: verification-done-vivid removed: verification-needed-vivid |
| tags: |
added: verification-done-wily removed: verification-needed-wily |
| Zsolt Dudás (v-zsduda) wrote | #15 |
| tags: |
added: verification-done-trusty removed: verification-needed-trusty |
| Launchpad Janitor (janitor) wrote | #16 |
| Changed in linux (Ubuntu Trusty): | |
| status: | Fix Committed → Fix Released |
| Launchpad Janitor (janitor) wrote | #17 |
| Changed in linux (Ubuntu Wily): | |
| status: | Fix Committed → Fix Released |
| Launchpad Janitor (janitor) wrote | #18 |
| Changed in linux (Ubuntu Vivid): | |
| status: | Fix Committed → Fix Released |
I don't see this patch in mainline as of yet. Is it in any upstream repos? Do you want me to build a test kernel with this patch?