This is a note to let you know that I've just added the patch titled
libceph: fix double __remove_osd() problem
to the 3.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
libceph-fix-double-__remove_osd-problem.patch
and it can be found in the queue-3.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 7eb71e0351fbb1b242ae70abb7bb17107fe2f792 Mon Sep 17 00:00:00 2001
From: Ilya Dryomov <idryomov@xxxxxxxxx>
Date: Tue, 17 Feb 2015 19:37:15 +0300
Subject: libceph: fix double __remove_osd() problem
From: Ilya Dryomov <idryomov@xxxxxxxxx>
commit 7eb71e0351fbb1b242ae70abb7bb17107fe2f792 upstream.
It turns out it's possible to get __remove_osd() called twice on the
same OSD. That doesn't sit well with rb_erase() - depending on the
shape of the tree we can get a NULL dereference, a soft lockup or
a random crash at some point in the future as we end up touching freed
memory. One scenario that I was able to reproduce is as follows:
<osd3 is idle, on the osd lru list>
<con reset - osd3>
con_fault_finish()
osd_reset()
<osdmap - osd3 down>
ceph_osdc_handle_map()
<takes map_sem>
kick_requests()
<takes request_mutex>
reset_changed_osds()
__reset_osd()
__remove_osd()
<releases request_mutex>
<releases map_sem>
<takes map_sem>
<takes request_mutex>
__kick_osd_requests()
__reset_osd()
__remove_osd() <-- !!!
A case can be made that osd refcounting is imperfect and reworking it
would be a proper resolution, but for now Sage and I decided to fix
this by adding a safe guard around __remove_osd().
Fixes: http://tracker.ceph.com/issues/8087
Cc: Sage Weil <sage@xxxxxxxxxx>
Signed-off-by: Ilya Dryomov <idryomov@xxxxxxxxx>
Reviewed-by: Sage Weil <sage@xxxxxxxxxx>
Reviewed-by: Alex Elder <elder@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/ceph/osd_client.c | 26 ++++++++++++++++++--------
1 file changed, 18 insertions(+), 8 deletions(-)
--- a/net/ceph/osd_client.c
+++ b/net/ceph/osd_client.c
@@ -967,14 +967,24 @@ static void put_osd(struct ceph_osd *osd
*/
static void __remove_osd(struct ceph_osd_client *osdc, struct ceph_osd *osd)
{
- dout("__remove_osd %p\n", osd);
+ dout("%s %p osd%d\n", __func__, osd, osd->o_osd);
WARN_ON(!list_empty(&osd->o_requests));
WARN_ON(!list_empty(&osd->o_linger_requests));
- rb_erase(&osd->o_node, &osdc->osds);
list_del_init(&osd->o_osd_lru);
- ceph_con_close(&osd->o_con);
- put_osd(osd);
+ rb_erase(&osd->o_node, &osdc->osds);
+ RB_CLEAR_NODE(&osd->o_node);
+}
+
+static void remove_osd(struct ceph_osd_client *osdc, struct ceph_osd *osd)
+{
+ dout("%s %p osd%d\n", __func__, osd, osd->o_osd);
+
+ if (!RB_EMPTY_NODE(&osd->o_node)) {
+ ceph_con_close(&osd->o_con);
+ __remove_osd(osdc, osd);
+ put_osd(osd);
+ }
}
static void remove_all_osds(struct ceph_osd_client *osdc)
@@ -984,7 +994,7 @@ static void remove_all_osds(struct ceph_
while (!RB_EMPTY_ROOT(&osdc->osds)) {
struct ceph_osd *osd = rb_entry(rb_first(&osdc->osds),
struct ceph_osd, o_node);
- __remove_osd(osdc, osd);
+ remove_osd(osdc, osd);
}
mutex_unlock(&osdc->request_mutex);
}
@@ -1014,7 +1024,7 @@ static void remove_old_osds(struct ceph_
list_for_each_entry_safe(osd, nosd, &osdc->osd_lru, o_osd_lru) {
if (time_before(jiffies, osd->lru_ttl))
break;
- __remove_osd(osdc, osd);
+ remove_osd(osdc, osd);
}
mutex_unlock(&osdc->request_mutex);
}
@@ -1029,8 +1039,7 @@ static int __reset_osd(struct ceph_osd_c
dout("__reset_osd %p osd%d\n", osd, osd->o_osd);
if (list_empty(&osd->o_requests) &&
list_empty(&osd->o_linger_requests)) {
- __remove_osd(osdc, osd);
-
+ remove_osd(osdc, osd);
return -ENODEV;
}
@@ -1612,6 +1621,7 @@ static void reset_changed_osds(struct ce
{
struct rb_node *p, *n;
+ dout("%s %p\n", __func__, osdc);
for (p = rb_first(&osdc->osds); p; p = n) {
struct ceph_osd *osd = rb_entry(p, struct ceph_osd, o_node);
Patches currently in stable-queue which might be from idryomov@xxxxxxxxx are
queue-3.10/libceph-fix-double-__remove_osd-problem.patch
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