When bfqq is shared by multiple processes it can happen that one of the processes gets moved to a different cgroup (or just starts submitting IO for different cgroup). In case that happens we need to split the merged bfqq as otherwise we will have IO for multiple cgroups in one bfqq and we will just account IO time to wrong entities etc.
Similarly if the bfqq is scheduled to merge with another bfqq but the merge didn't happen yet, cancel the merge as it need not be valid anymore.
CC: stable@vger.kernel.org Fixes: e21b7a0b9887 ("block, bfq: add full hierarchical scheduling and cgroups support") Signed-off-by: Jan Kara jack@suse.cz --- block/bfq-cgroup.c | 25 ++++++++++++++++++++++++- block/bfq-iosched.c | 2 +- block/bfq-iosched.h | 1 + 3 files changed, 26 insertions(+), 2 deletions(-)
diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c index 24a5c5329bcd..dbc117e00783 100644 --- a/block/bfq-cgroup.c +++ b/block/bfq-cgroup.c @@ -730,8 +730,31 @@ static struct bfq_group *__bfq_bic_change_cgroup(struct bfq_data *bfqd,
if (sync_bfqq) { entity = &sync_bfqq->entity; - if (entity->sched_data != &bfqg->sched_data) + if (entity->sched_data != &bfqg->sched_data) { + /* + * Was the queue we use merged to a different queue? + * Detach process from the queue as merge need not be + * valid anymore. We cannot easily cancel the merge as + * there may be other processes scheduled to this + * queue. + */ + if (sync_bfqq->new_bfqq) { + bfq_put_cooperator(sync_bfqq); + bfq_release_process_ref(bfqd, sync_bfqq); + bic_set_bfqq(bic, NULL, 1); + return bfqg; + } + /* + * Moving bfqq that is shared with another process? + * Split the queues at the nearest occasion as the + * processes can be in different cgroups now. + */ + if (bfq_bfqq_coop(sync_bfqq)) { + bic->stably_merged = false; + bfq_mark_bfqq_split_coop(sync_bfqq); + } bfq_bfqq_move(bfqd, sync_bfqq, bfqg); + } }
return bfqg; diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c index 0da47f2ca781..361d321b012a 100644 --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -5184,7 +5184,7 @@ static void bfq_put_stable_ref(struct bfq_queue *bfqq) bfq_put_queue(bfqq); }
-static void bfq_put_cooperator(struct bfq_queue *bfqq) +void bfq_put_cooperator(struct bfq_queue *bfqq) { struct bfq_queue *__bfqq, *next;
diff --git a/block/bfq-iosched.h b/block/bfq-iosched.h index a73488eec8a4..6e250db2138e 100644 --- a/block/bfq-iosched.h +++ b/block/bfq-iosched.h @@ -976,6 +976,7 @@ void bfq_weights_tree_remove(struct bfq_data *bfqd, void bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq, bool compensate, enum bfqq_expiration reason); void bfq_put_queue(struct bfq_queue *bfqq); +void bfq_put_cooperator(struct bfq_queue *bfqq); void bfq_end_wr_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg); void bfq_release_process_ref(struct bfq_data *bfqd, struct bfq_queue *bfqq); void bfq_schedule_dispatch(struct bfq_data *bfqd);
在 2022/01/12 19:39, Jan Kara 写道:
When bfqq is shared by multiple processes it can happen that one of the processes gets moved to a different cgroup (or just starts submitting IO for different cgroup). In case that happens we need to split the merged bfqq as otherwise we will have IO for multiple cgroups in one bfqq and we will just account IO time to wrong entities etc.
Similarly if the bfqq is scheduled to merge with another bfqq but the merge didn't happen yet, cancel the merge as it need not be valid anymore.
CC: stable@vger.kernel.org Fixes: e21b7a0b9887 ("block, bfq: add full hierarchical scheduling and cgroups support") Signed-off-by: Jan Kara jack@suse.cz
block/bfq-cgroup.c | 25 ++++++++++++++++++++++++- block/bfq-iosched.c | 2 +- block/bfq-iosched.h | 1 + 3 files changed, 26 insertions(+), 2 deletions(-)
diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c index 24a5c5329bcd..dbc117e00783 100644 --- a/block/bfq-cgroup.c +++ b/block/bfq-cgroup.c @@ -730,8 +730,31 @@ static struct bfq_group *__bfq_bic_change_cgroup(struct bfq_data *bfqd, if (sync_bfqq) { entity = &sync_bfqq->entity;
if (entity->sched_data != &bfqg->sched_data)
if (entity->sched_data != &bfqg->sched_data) {/** Was the queue we use merged to a different queue?* Detach process from the queue as merge need not be* valid anymore. We cannot easily cancel the merge as* there may be other processes scheduled to this* queue.*/if (sync_bfqq->new_bfqq) {bfq_put_cooperator(sync_bfqq);
Hi,
The patch " bfq: Simplify bfq_put_cooperator()" in last version is not in this patch set, thus bfq_put_cooperator() won't set sync_bfqq->new_bfqq to NULL. So I guess the problem still exist?
Thanks, Kuai
bfq_release_process_ref(bfqd, sync_bfqq);bic_set_bfqq(bic, NULL, 1);return bfqg;}/** Moving bfqq that is shared with another process?* Split the queues at the nearest occasion as the* processes can be in different cgroups now.*/if (bfq_bfqq_coop(sync_bfqq)) {bic->stably_merged = false;bfq_mark_bfqq_split_coop(sync_bfqq);} bfq_bfqq_move(bfqd, sync_bfqq, bfqg);}return bfqg; diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c index 0da47f2ca781..361d321b012a 100644 --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -5184,7 +5184,7 @@ static void bfq_put_stable_ref(struct bfq_queue *bfqq) bfq_put_queue(bfqq); } -static void bfq_put_cooperator(struct bfq_queue *bfqq) +void bfq_put_cooperator(struct bfq_queue *bfqq) { struct bfq_queue *__bfqq, *next; diff --git a/block/bfq-iosched.h b/block/bfq-iosched.h index a73488eec8a4..6e250db2138e 100644 --- a/block/bfq-iosched.h +++ b/block/bfq-iosched.h @@ -976,6 +976,7 @@ void bfq_weights_tree_remove(struct bfq_data *bfqd, void bfq_bfqq_expire(struct bfq_data *bfqd, struct bfq_queue *bfqq, bool compensate, enum bfqq_expiration reason); void bfq_put_queue(struct bfq_queue *bfqq); +void bfq_put_cooperator(struct bfq_queue *bfqq); void bfq_end_wr_async_queues(struct bfq_data *bfqd, struct bfq_group *bfqg); void bfq_release_process_ref(struct bfq_data *bfqd, struct bfq_queue *bfqq); void bfq_schedule_dispatch(struct bfq_data *bfqd);
在 2022/01/13 11:57, yukuai (C) 写道:
在 2022/01/12 19:39, Jan Kara 写道:
When bfqq is shared by multiple processes it can happen that one of the processes gets moved to a different cgroup (or just starts submitting IO for different cgroup). In case that happens we need to split the merged bfqq as otherwise we will have IO for multiple cgroups in one bfqq and we will just account IO time to wrong entities etc.
Similarly if the bfqq is scheduled to merge with another bfqq but the merge didn't happen yet, cancel the merge as it need not be valid anymore.
CC: stable@vger.kernel.org Fixes: e21b7a0b9887 ("block, bfq: add full hierarchical scheduling and cgroups support") Signed-off-by: Jan Kara jack@suse.cz
block/bfq-cgroup.c | 25 ++++++++++++++++++++++++- block/bfq-iosched.c | 2 +- block/bfq-iosched.h | 1 + 3 files changed, 26 insertions(+), 2 deletions(-)
diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c index 24a5c5329bcd..dbc117e00783 100644 --- a/block/bfq-cgroup.c +++ b/block/bfq-cgroup.c @@ -730,8 +730,31 @@ static struct bfq_group *__bfq_bic_change_cgroup(struct bfq_data *bfqd, if (sync_bfqq) { entity = &sync_bfqq->entity; - if (entity->sched_data != &bfqg->sched_data) + if (entity->sched_data != &bfqg->sched_data) { + /* + * Was the queue we use merged to a different queue? + * Detach process from the queue as merge need not be + * valid anymore. We cannot easily cancel the merge as + * there may be other processes scheduled to this + * queue. + */ + if (sync_bfqq->new_bfqq) { + bfq_put_cooperator(sync_bfqq);
Hi,
The patch " bfq: Simplify bfq_put_cooperator()" in last version is not in this patch set, thus bfq_put_cooperator() won't set sync_bfqq->new_bfqq to NULL. So I guess the problem still exist?
Thanks, Kuai
+ bfq_release_process_ref(bfqd, sync_bfqq); + bic_set_bfqq(bic, NULL, 1);
Hi,
I understand now that you set NULL here, however I still can repoduce the problem with this patch set applied.
Here I add some debug message:
diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c index dbc117e00783..2d3da8e73ec0 100644 --- a/block/bfq-cgroup.c +++ b/block/bfq-cgroup.c @@ -754,6 +754,7 @@ static struct bfq_group *__bfq_bic_change_cgroup(struct bfq_data *bfqd, bfq_mark_bfqq_split_coop(sync_bfqq); } bfq_bfqq_move(bfqd, sync_bfqq, bfqg); + printk("%s: bfqq %px move to %px\n", __func__, sync_bfqq, bfqg); } }
diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c index 07be51bc229b..74d5b575626f 100644 --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -2797,6 +2797,7 @@ bfq_setup_merge(struct bfq_queue *bfqq, struct bfq_queue *new_bfqq) * are likely to increase the throughput. */ bfqq->new_bfqq = new_bfqq; + printk("%s: bfqq %px new_bfqq %px bfqg %px\n", __func__, bfqq, new_bfqq, bfqq_group(bfqq)); new_bfqq->ref += process_refs; return new_bfqq; } @@ -2963,8 +2964,14 @@ bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq, if (bfq_too_late_for_merging(bfqq)) return NULL;
- if (bfqq->new_bfqq) + if (bfqq->new_bfqq) { + if (bfqq->entity.parent != bfqq->new_bfqq->entity.parent) { + printk("%s: bfqq %px (%px), new_bfqq %px (%px)\n", __func__, + bfqq, bfqq_group(bfqq), bfqq->new_bfqq, bfqq_group(bfqq->new_bfqq)); + BUG_ON(1); + } return bfqq->new_bfqq; + }
if (!io_struct || unlikely(bfqq == &bfqd->oom_bfqq)) return NULL;
And here is the messages when BUG_ON is triggered（much easier than the uaf problem):
[ 157.237821] bfq_setup_merge: bfqq ffff888140654dc0 new_bfqq ffff888174122100 bfqg ffff88817abc6000 [ 157.238739] __bfq_bic_change_cgroup: bfqq ffff888174122100 move to ffff888104b7c000 [ 157.239675] bfq_setup_cooperator: bfqq ffff888140654dc0 (ffff88817abc6000), new_bfqq ffff888174122100 (ffff888104b7c000) [ 157.240696] ------------[ cut here ]------------ [ 157.241113] kernel BUG at block/bfq-iosched.c:2971! [ 157.241565] invalid opcode: 0000 [#1] PREEMPT SMP KASAN [ 157.242042] CPU: 4 PID: 3089 Comm: fio Tainted: G W 5.16.0-next-20220111+ #361 [ 157.242810] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20190727_073836-buildvm-ppc64le-16.ppc.fedoraproject.org-3.fc31 04/01/2014 [ 157.243985] RIP: 0010:bfq_setup_cooperator+0x413/0x7e0 [ 157.244470] Code: 8b 65 30 48 89 ef e8 9c ab 00 00 49 89 d9 48 89 ea 48 c7 c6 00 d9 d9 82 48 89 c1 4d 89 e0 48 c7 c7 80 d4 d9 82 e8 88 3f 91 00 <0f> 0b 48 8d bd f0 01 00 00 e8 0f 77 84 c [ 157.246132] RSP: 0018:ffff888171ecf1e0 EFLAGS: 00010082 [ 157.246609] RAX: 000000000000006c RBX: ffff888104b7c000 RCX: 0000000000000000 [ 157.247243] RDX: 0000000000000002 RSI: ffffffff82da9fc0 RDI: ffffed102e3d9e2f [ 157.247889] RBP: ffff888140654dc0 R08: 000000000000006c R09: ffffed106cd06751 [ 157.248529] R10: ffff888366833a87 R11: ffffed106cd06750 R12: ffff888174122100 [ 157.249160] R13: 0000000000000000 R14: ffff88817abc5000 R15: ffff888174122100 [ 157.249801] FS: 00007f21fe8d5700(0000) GS:ffff888366800000(0000) knlGS:0000000000000000 [ 157.250524] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 157.251042] CR2: 000055f2bb593770 CR3: 0000000105045000 CR4: 00000000000006e0 [ 157.251688] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 157.252327] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 157.252970] Call Trace: [ 157.253207] <TASK> [ 157.253418] ? bic_set_bfqq+0x80/0x80 [ 157.253757] ? memcpy+0x39/0x60 [ 157.254052] ? blk_integrity_merge_bio+0x2e/0x150 [ 157.254490] bfq_allow_bio_merge+0x9a/0x130 [ 157.254874] elv_merge+0x76/0x1b0 [ 157.255185] blk_mq_sched_try_merge+0x7a/0x2c0 [ 157.255603] ? preempt_count_sub+0x14/0xc0 [ 157.255985] ? bio_attempt_front_merge+0x8b0/0x8b0 [ 157.256427] ? kernfs_path_from_node+0x4c/0x60 [ 157.256839] ? bfq_bic_update_cgroup+0x211/0x2c0 [ 157.257269] bfq_bio_merge+0x141/0x1d0 [ 157.257629] ? bfq_request_merge+0xe0/0xe0 [ 157.258001] ? blk_mq_sched_bio_merge+0x43/0x170 [ 157.258426] blk_mq_submit_bio+0x7a6/0xba0 [ 157.258800] ? submit_bio_checks+0x4ed/0x9f0 [ 157.259191] ? blk_mq_try_issue_list_directly+0x1d0/0x1d0 [ 157.259685] ? mempool_alloc+0x250/0x250 [ 157.260040] ? mempool_destroy+0x20/0x20 [ 157.260401] ? __submit_bio+0x61/0x290 [ 157.260751] submit_bio_noacct+0x441/0x480 [ 157.261125] ? __submit_bio+0x290/0x290 [ 157.261486] ? bio_add_page+0xbc/0x100 [ 157.261831] submit_bh_wbc+0x2e7/0x320 [ 157.262179] __block_write_full_page+0x3f3/0x870 [ 157.262609] ? blkdev_write_end+0x150/0x150 [ 157.262994] ? end_buffer_write_sync+0xa0/0xa0 [ 157.263401] __writepage+0x39/0xb0 [ 157.263718] write_cache_pages+0x27e/0x840 [ 157.264091] ? tag_pages_for_writeback+0x250/0x250 [ 157.264538] ? wb_writeout_inc+0x150/0x150 [ 157.264919] ? _raw_spin_lock_irqsave+0xe0/0xe0 [ 157.265339] ? xas_start+0x7b/0x170 [ 157.265673] generic_writepages+0xb9/0x110 [ 157.266042] ? write_cache_pages+0x840/0x840 [ 157.266432] ? xas_set_mark+0xd0/0xd0 [ 157.266765] do_writepages+0x104/0x320 [ 157.267106] ? __rcu_read_unlock+0x4e/0x250 [ 157.267492] ? page_writeback_cpu_online+0x10/0x10 [ 157.267919] ? _raw_spin_lock+0x87/0xe0 [ 157.268264] ? _raw_spin_lock_irqsave+0xe0/0xe0 [ 157.268676] ? inode_to_bdi+0x79/0x90 [ 157.269012] filemap_fdatawrite_wbc+0x91/0xc0 [ 157.269412] filemap_write_and_wait_range+0xbb/0x140 [ 157.269851] ? filemap_fdatawait_keep_errors+0x30/0x30 [ 157.270309] ? generic_file_direct_write+0xcb/0x250 [ 157.270748] __generic_file_write_iter+0x1fc/0x250 [ 157.271175] blkdev_write_iter+0x21a/0x300 [ 157.271547] ? blkdev_llseek+0x80/0x80 [ 157.271884] ? preempt_count_sub+0x14/0xc0 [ 157.272247] ? __update_load_avg_cfs_rq+0x51/0x530 [ 157.272678] ? __update_load_avg_cfs_rq+0x51/0x530 [ 157.273111] new_sync_write+0x24c/0x360 [ 157.273464] ? new_sync_read+0x360/0x360 [ 157.273819] ? set_next_entity+0xb1/0x280 [ 157.274178] ? preempt_count_sub+0x14/0xc0 [ 157.274551] ? __rcu_read_unlock+0x4e/0x250 [ 157.274926] vfs_write+0x291/0x3d0 [ 157.275238] ksys_pwrite64+0xe7/0x110 [ 157.275580] ? __ia32_sys_pread64+0x60/0x60 [ 157.275954] ? switch_fpu_return+0x9d/0x140 [ 157.276329] do_syscall_64+0x35/0x80 [ 157.276659] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 157.277110] RIP: 0033:0x7f220f1f0b23
It seems that when q1 and q2 are merged(q1->new_bfqq = q2), and q2 is moved to another bfqg through __bfq_bic_change_cgroug(), the q2 is not split before the bfq_setup_cooperator() is called.
Thanks, Kuai
On Thu 13-01-22 15:08:50, yukuai (C) wrote:
在 2022/01/13 11:57, yukuai (C) 写道:
在 2022/01/12 19:39, Jan Kara 写道:
When bfqq is shared by multiple processes it can happen that one of the processes gets moved to a different cgroup (or just starts submitting IO for different cgroup). In case that happens we need to split the merged bfqq as otherwise we will have IO for multiple cgroups in one bfqq and we will just account IO time to wrong entities etc.
Similarly if the bfqq is scheduled to merge with another bfqq but the merge didn't happen yet, cancel the merge as it need not be valid anymore.
CC: stable@vger.kernel.org Fixes: e21b7a0b9887 ("block, bfq: add full hierarchical scheduling and cgroups support") Signed-off-by: Jan Kara jack@suse.cz
block/bfq-cgroup.c | 25 ++++++++++++++++++++++++- block/bfq-iosched.c | 2 +- block/bfq-iosched.h | 1 + 3 files changed, 26 insertions(+), 2 deletions(-)
diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c index 24a5c5329bcd..dbc117e00783 100644 --- a/block/bfq-cgroup.c +++ b/block/bfq-cgroup.c @@ -730,8 +730,31 @@ static struct bfq_group *__bfq_bic_change_cgroup(struct bfq_data *bfqd, if (sync_bfqq) { entity = &sync_bfqq->entity; - if (entity->sched_data != &bfqg->sched_data) + if (entity->sched_data != &bfqg->sched_data) { + /* + * Was the queue we use merged to a different queue? + * Detach process from the queue as merge need not be + * valid anymore. We cannot easily cancel the merge as + * there may be other processes scheduled to this + * queue. + */ + if (sync_bfqq->new_bfqq) { + bfq_put_cooperator(sync_bfqq);
Hi,
The patch " bfq: Simplify bfq_put_cooperator()" in last version is not in this patch set, thus bfq_put_cooperator() won't set sync_bfqq->new_bfqq to NULL. So I guess the problem still exist?
Thanks, Kuai
+ bfq_release_process_ref(bfqd, sync_bfqq); + bic_set_bfqq(bic, NULL, 1);
Hi,
I understand now that you set NULL here,
Yes.
however I still can repoduce the problem with this patch set applied.
OK.
Here I add some debug message:
diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c index dbc117e00783..2d3da8e73ec0 100644 --- a/block/bfq-cgroup.c +++ b/block/bfq-cgroup.c @@ -754,6 +754,7 @@ static struct bfq_group *__bfq_bic_change_cgroup(struct bfq_data *bfqd, bfq_mark_bfqq_split_coop(sync_bfqq); } bfq_bfqq_move(bfqd, sync_bfqq, bfqg);
printk("%s: bfqq %px move to %px\n", __func__,sync_bfqq, bfqg); } }
diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c index 07be51bc229b..74d5b575626f 100644 --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -2797,6 +2797,7 @@ bfq_setup_merge(struct bfq_queue *bfqq, struct bfq_queue *new_bfqq) * are likely to increase the throughput. */ bfqq->new_bfqq = new_bfqq;
printk("%s: bfqq %px new_bfqq %px bfqg %px\n", __func__, bfqq,new_bfqq, bfqq_group(bfqq)); new_bfqq->ref += process_refs; return new_bfqq; } @@ -2963,8 +2964,14 @@ bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq, if (bfq_too_late_for_merging(bfqq)) return NULL;
if (bfqq->new_bfqq)
if (bfqq->new_bfqq) {if (bfqq->entity.parent != bfqq->new_bfqq->entity.parent) {printk("%s: bfqq %px (%px), new_bfqq %px (%px)\n",__func__,
bfqq, bfqq_group(bfqq),bfqq->new_bfqq, bfqq_group(bfqq->new_bfqq));
BUG_ON(1);} return bfqq->new_bfqq;} if (!io_struct || unlikely(bfqq == &bfqd->oom_bfqq)) return NULL;And here is the messages when BUG_ON is triggered（much easier than the uaf problem):
[ 157.237821] bfq_setup_merge: bfqq ffff888140654dc0 new_bfqq ffff888174122100 bfqg ffff88817abc6000 [ 157.238739] __bfq_bic_change_cgroup: bfqq ffff888174122100 move to ffff888104b7c000 [ 157.239675] bfq_setup_cooperator: bfqq ffff888140654dc0 (ffff88817abc6000), new_bfqq ffff888174122100 (ffff888104b7c000)
Thanks for the debugging! So this shows that it is not 'bfqq' that changed parent but rather bfqq->new_bfqq that changed parent. And presumably it can even happen that the bfqq->new_bfqq parent gets offlined and UAF eventually triggered. Indeed, I didn't think about that possibility. I have to think how to handle this in the best way...
Honza
linux-stable-mirror@lists.linaro.org
-
Jan Kara -
yukuai (C)