[PATCH] dm: fix rh_dec()/rh_inc() race in dm-raid1.c (844e8d90) · Commits · 戴 / test

Fix another bug in dm-raid1.c that the dirty region may stay in or be moved to clean list and freed while in use. It happens as follows: CPU0 CPU1 ------------------------------------------------------------------------------ rh_dec() if (atomic_dec_and_test(pending)) <the region is still marked dirty> rh_inc() if the region is clean mark the region dirty and remove from clean list mark the region clean and move to clean list atomic_inc(pending) At this stage, the region is in clean list and will be mistakenly reclaimed by rh_update_states() later. Signed-off-by:

Jun'ichi Nomura <j-nomura@ce.jp.nec.com> Signed-off-by:

Andrew Morton <akpm@osdl.org> Signed-off-by:

Linus Torvalds <torvalds@osdl.org>

drivers/md/dm-raid1.c

+9 −3

Original line number	Diff line number	Diff line
		@@ -375,16 +375,18 @@ static void rh_inc(struct region_hash *rh, region_t region)

		read_lock(&rh->hash_lock);
		reg = __rh_find(rh, region);

		atomic_inc(&reg->pending);

		spin_lock_irq(&rh->region_lock);
		if (reg->state == RH_CLEAN) {
		rh->log->type->mark_region(rh->log, reg->key);

		spin_lock_irq(&rh->region_lock);
		reg->state = RH_DIRTY;
		list_del_init(&reg->list); /* take off the clean list */
		spin_unlock_irq(&rh->region_lock);
		}
		spin_unlock_irq(&rh->region_lock);

		atomic_inc(&reg->pending);
		read_unlock(&rh->hash_lock);
		}

		@@ -408,6 +410,10 @@ static void rh_dec(struct region_hash *rh, region_t region)

		if (atomic_dec_and_test(&reg->pending)) {
		spin_lock_irqsave(&rh->region_lock, flags);
		if (atomic_read(&reg->pending)) { /* check race */
		spin_unlock_irqrestore(&rh->region_lock, flags);
		return;
		}
		if (reg->state == RH_RECOVERING) {
		list_add_tail(&reg->list, &rh->quiesced_regions);
		} else {

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