From: Yu Kuai yukuai3@huawei.com
If cfqq is merged with another cfqq(assume that no cfqq is merged to this cfqq) and then user thread is moved to another cgroup, then check_blkcg_changed() will set cic->cfqq[1] to NULL. However, this cfqq is still merged and no one will referece this cfqq, which will cause following kmemleak:
comm "cgexec", pid 2541110, jiffies 4317578508 (age 5728.064s) hex dump (first 32 bytes): 03 00 00 00 90 03 00 00 80 8d 0f be 20 80 ff ff ............ ... a0 16 c6 a1 21 80 ff ff 00 00 00 00 00 00 00 00 ....!........... backtrace: [<0000000071d2775e>] kmem_cache_alloc_node+0x13c/0x660 [<00000000e827e6fd>] cfq_get_queue+0x318/0x6f0 [<00000000945249ee>] cfq_set_request+0x724/0xe38 [<00000000af64d5a9>] elv_set_request+0x84/0xd0 [<0000000047344f0d>] __get_request+0x970/0xf90 [<00000000d016bd51>] get_request+0x278/0x970 [<0000000052512d36>] blk_queue_bio+0x278/0xcc0 [<0000000085282101>] generic_make_request+0x3c0/0x778 [<0000000089f69c24>] submit_bio+0xdc/0x408 [<00000000748509ae>] ext4_mpage_readpages+0xc84/0x13b8 [ext4] [<0000000078bfc705>] ext4_readpages+0x80/0xc0 [ext4] [<00000000317f2ed7>] read_pages+0xd0/0x610 [<00000000e7ab01d2>] __do_page_cache_readahead+0x36c/0x430 [<0000000071df2285>] ondemand_readahead+0x24c/0x6b0 [<00000000124a824a>] page_cache_sync_readahead+0x188/0x448 [<00000000bca561ae>] generic_file_buffered_read+0x648/0x2b58 unreferenced object 0xffffa028411d4720 (size 240):
Fix the problem by put cooperator in check_blkcg_changed(), so that old cfqq can be freed.
Signed-off-by: Yu Kuai yukuai3@huawei.com --- block/cfq-iosched.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 2eb87444b157..88bae553ece3 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -3778,6 +3778,7 @@ static void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio) if (cfqq) { cfq_log_cfqq(cfqd, cfqq, "changed cgroup"); cic_set_cfqq(cic, NULL, true); + cfq_put_cooperator(cfqq); cfq_put_queue(cfqq); }
Hi,
Thanks for your patch.
FYI: kernel test robot notices the stable kernel rule is not satisfied.
Rule: 'Cc: stable@vger.kernel.org' or 'commit <sha1> upstream.' Subject: [PATCH 4.19] cfq: fix memory leak for cfqq Link: https://lore.kernel.org/stable/20230202135850.2415165-1-yukuai1%40huaweiclou...
The check is based on https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
On Thu, Feb 02, 2023 at 09:58:50PM +0800, Yu Kuai wrote:
From: Yu Kuai yukuai3@huawei.com
If cfqq is merged with another cfqq(assume that no cfqq is merged to this cfqq) and then user thread is moved to another cgroup, then check_blkcg_changed() will set cic->cfqq[1] to NULL. However, this cfqq is still merged and no one will referece this cfqq, which will cause following kmemleak:
comm "cgexec", pid 2541110, jiffies 4317578508 (age 5728.064s) hex dump (first 32 bytes): 03 00 00 00 90 03 00 00 80 8d 0f be 20 80 ff ff ............ ... a0 16 c6 a1 21 80 ff ff 00 00 00 00 00 00 00 00 ....!........... backtrace: [<0000000071d2775e>] kmem_cache_alloc_node+0x13c/0x660 [<00000000e827e6fd>] cfq_get_queue+0x318/0x6f0 [<00000000945249ee>] cfq_set_request+0x724/0xe38 [<00000000af64d5a9>] elv_set_request+0x84/0xd0 [<0000000047344f0d>] __get_request+0x970/0xf90 [<00000000d016bd51>] get_request+0x278/0x970 [<0000000052512d36>] blk_queue_bio+0x278/0xcc0 [<0000000085282101>] generic_make_request+0x3c0/0x778 [<0000000089f69c24>] submit_bio+0xdc/0x408 [<00000000748509ae>] ext4_mpage_readpages+0xc84/0x13b8 [ext4] [<0000000078bfc705>] ext4_readpages+0x80/0xc0 [ext4] [<00000000317f2ed7>] read_pages+0xd0/0x610 [<00000000e7ab01d2>] __do_page_cache_readahead+0x36c/0x430 [<0000000071df2285>] ondemand_readahead+0x24c/0x6b0 [<00000000124a824a>] page_cache_sync_readahead+0x188/0x448 [<00000000bca561ae>] generic_file_buffered_read+0x648/0x2b58 unreferenced object 0xffffa028411d4720 (size 240):
Fix the problem by put cooperator in check_blkcg_changed(), so that old cfqq can be freed.
Signed-off-by: Yu Kuai yukuai3@huawei.com
block/cfq-iosched.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index 2eb87444b157..88bae553ece3 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -3778,6 +3778,7 @@ static void check_blkcg_changed(struct cfq_io_cq *cic, struct bio *bio) if (cfqq) { cfq_log_cfqq(cfqd, cfqq, "changed cgroup"); cic_set_cfqq(cic, NULL, true);
cfq_put_cooperator(cfqq);2.31.1
<formletter>
This is not the correct way to submit patches for inclusion in the stable kernel tree. Please read: https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html for how to do this properly.
</formletter>
linux-stable-mirror@lists.linaro.org
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Greg KH -
kernel test robot -
Yu Kuai