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authorJun'ichi Nomura <j-nomura@ce.jp.nec.com>2013-03-01 22:45:44 +0000
committerAlasdair G Kergon <agk@redhat.com>2013-03-01 22:45:44 +0000
commit16245bdc9d3e22d1460341a655c8b5288953bc14 (patch)
tree61b6373392d2c074c2fc18203c6b9134174bed4b
parentb6669737d3db7df79fad07180837c23dbe581db5 (diff)
dm: do not replace bioset for request based dm
This patch fixes a regression introduced in v3.8, which causes oops like this when dm-multipath is used: general protection fault: 0000 [#1] SMP RIP: 0010:[<ffffffff810fe754>] [<ffffffff810fe754>] mempool_free+0x24/0xb0 Call Trace: <IRQ> [<ffffffff81187417>] bio_put+0x97/0xc0 [<ffffffffa02247a5>] end_clone_bio+0x35/0x90 [dm_mod] [<ffffffff81185efd>] bio_endio+0x1d/0x30 [<ffffffff811f03a3>] req_bio_endio.isra.51+0xa3/0xe0 [<ffffffff811f2f68>] blk_update_request+0x118/0x520 [<ffffffff811f3397>] blk_update_bidi_request+0x27/0xa0 [<ffffffff811f343c>] blk_end_bidi_request+0x2c/0x80 [<ffffffff811f34d0>] blk_end_request+0x10/0x20 [<ffffffffa000b32b>] scsi_io_completion+0xfb/0x6c0 [scsi_mod] [<ffffffffa000107d>] scsi_finish_command+0xbd/0x120 [scsi_mod] [<ffffffffa000b12f>] scsi_softirq_done+0x13f/0x160 [scsi_mod] [<ffffffff811f9fd0>] blk_done_softirq+0x80/0xa0 [<ffffffff81044551>] __do_softirq+0xf1/0x250 [<ffffffff8142ee8c>] call_softirq+0x1c/0x30 [<ffffffff8100420d>] do_softirq+0x8d/0xc0 [<ffffffff81044885>] irq_exit+0xd5/0xe0 [<ffffffff8142f3e3>] do_IRQ+0x63/0xe0 [<ffffffff814257af>] common_interrupt+0x6f/0x6f <EOI> [<ffffffffa021737c>] srp_queuecommand+0x8c/0xcb0 [ib_srp] [<ffffffffa0002f18>] scsi_dispatch_cmd+0x148/0x310 [scsi_mod] [<ffffffffa000a38e>] scsi_request_fn+0x31e/0x520 [scsi_mod] [<ffffffff811f1e57>] __blk_run_queue+0x37/0x50 [<ffffffff811f1f69>] blk_delay_work+0x29/0x40 [<ffffffff81059003>] process_one_work+0x1c3/0x5c0 [<ffffffff8105b22e>] worker_thread+0x15e/0x440 [<ffffffff8106164b>] kthread+0xdb/0xe0 [<ffffffff8142db9c>] ret_from_fork+0x7c/0xb0 The regression was introduced by the change c0820cf5 "dm: introduce per_bio_data", where dm started to replace bioset during table replacement. For bio-based dm, it is good because clone bios do not exist during the table replacement. For request-based dm, however, (not-yet-mapped) clone bios may stay in request queue and survive during the table replacement. So freeing the old bioset could cause the oops in bio_put(). Since the size of front_pad may change only with bio-based dm, it is not necessary to replace bioset for request-based dm. Reported-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com> Acked-by: Mikulas Patocka <mpatocka@redhat.com> Acked-by: Mike Snitzer <snitzer@redhat.com> Cc: <stable@vger.kernel.org> Signed-off-by: Alasdair G Kergon <agk@redhat.com>
-rw-r--r--drivers/md/dm.c30
1 files changed, 21 insertions, 9 deletions
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index bb2cd3ce9b0f..38486df61f58 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1947,15 +1947,27 @@ static void __bind_mempools(struct mapped_device *md, struct dm_table *t)
{
struct dm_md_mempools *p = dm_table_get_md_mempools(t);
- if (md->io_pool && (md->tio_pool || dm_table_get_type(t) == DM_TYPE_BIO_BASED) && md->bs) {
- /*
- * The md already has necessary mempools. Reload just the
- * bioset because front_pad may have changed because
- * a different table was loaded.
- */
- bioset_free(md->bs);
- md->bs = p->bs;
- p->bs = NULL;
+ if (md->io_pool && md->bs) {
+ /* The md already has necessary mempools. */
+ if (dm_table_get_type(t) == DM_TYPE_BIO_BASED) {
+ /*
+ * Reload bioset because front_pad may have changed
+ * because a different table was loaded.
+ */
+ bioset_free(md->bs);
+ md->bs = p->bs;
+ p->bs = NULL;
+ } else if (dm_table_get_type(t) == DM_TYPE_REQUEST_BASED) {
+ BUG_ON(!md->tio_pool);
+ /*
+ * There's no need to reload with request-based dm
+ * because the size of front_pad doesn't change.
+ * Note for future: If you are to reload bioset,
+ * prep-ed requests in the queue may refer
+ * to bio from the old bioset, so you must walk
+ * through the queue to unprep.
+ */
+ }
goto out;
}