lkml.org 
[lkml]   [2015]   [Mar]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 3.16.y-ckt 140/183] libceph: fix double __remove_osd() problem
Date
3.16.7-ckt8 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ilya Dryomov <idryomov@gmail.com>

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@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Sage Weil <sage@redhat.com>
Reviewed-by: Alex Elder <elder@linaro.org>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
---
net/ceph/osd_client.c | 26 ++++++++++++++++++--------
1 file changed, 18 insertions(+), 8 deletions(-)

diff --git a/net/ceph/osd_client.c b/net/ceph/osd_client.c
index 18a59c60a2b7..8cbd41f5c424 100644
--- a/net/ceph/osd_client.c
+++ b/net/ceph/osd_client.c
@@ -1006,14 +1006,24 @@ 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)
@@ -1023,7 +1033,7 @@ static void remove_all_osds(struct ceph_osd_client *osdc)
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);
}
@@ -1053,7 +1063,7 @@ static void remove_old_osds(struct ceph_osd_client *osdc)
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);
}
@@ -1068,8 +1078,7 @@ static int __reset_osd(struct ceph_osd_client *osdc, struct ceph_osd *osd)
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;
}

@@ -1869,6 +1878,7 @@ static void reset_changed_osds(struct ceph_osd_client *osdc)
{
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);


\
 
 \ /
  Last update: 2015-03-06 11:21    [W:0.475 / U:0.472 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site