Skip to content

Fix a recently introduced deadlock #371

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
wants to merge 2 commits into
base: linus-master_base
Choose a base branch
from
Open

Fix a recently introduced deadlock #371

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
4eca3ea
fs: Add the __data_racy annotation to backing_dev_info.ra_pages
bvanassche Nov 14, 2025
b1e2d70
block: Remove queue freezing from several sysfs store callbacks
bvanassche Nov 14, 2025
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
26 changes: 8 additions & 18 deletions block/blk-sysfs.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -143,21 +143,22 @@ queue_ra_store(struct gendisk *disk, const char *page, size_t count)
{
unsigned long ra_kb;
ssize_t ret;
unsigned int memflags;
struct request_queue *q = disk->queue;

ret = queue_var_store(&ra_kb, page, count);
if (ret < 0)
return ret;
/*
* ->ra_pages is protected by ->limits_lock because it is usually
* calculated from the queue limits by queue_limits_commit_update.
* The ->ra_pages change below is protected by ->limits_lock because it
* is usually calculated from the queue limits by
* queue_limits_commit_update().
*
* bdi->ra_pages reads are not serialized against bdi->ra_pages writes.
* Use WRITE_ONCE() to write bdi->ra_pages once.
*/
mutex_lock(&q->limits_lock);
memflags = blk_mq_freeze_queue(q);
disk->bdi->ra_pages = ra_kb >> (PAGE_SHIFT - 10);
WRITE_ONCE(disk->bdi->ra_pages, ra_kb >> (PAGE_SHIFT - 10));
mutex_unlock(&q->limits_lock);
blk_mq_unfreeze_queue(q, memflags);

return ret;
}
Expand Down Expand Up @@ -375,21 +376,18 @@ static ssize_t queue_nomerges_store(struct gendisk *disk, const char *page,
size_t count)
{
unsigned long nm;
unsigned int memflags;
struct request_queue *q = disk->queue;
ssize_t ret = queue_var_store(&nm, page, count);

if (ret < 0)
return ret;

memflags = blk_mq_freeze_queue(q);
blk_queue_flag_clear(QUEUE_FLAG_NOMERGES, q);
blk_queue_flag_clear(QUEUE_FLAG_NOXMERGES, q);
if (nm == 2)
blk_queue_flag_set(QUEUE_FLAG_NOMERGES, q);
else if (nm)
blk_queue_flag_set(QUEUE_FLAG_NOXMERGES, q);
blk_mq_unfreeze_queue(q, memflags);

return ret;
}
Expand All @@ -409,7 +407,6 @@ queue_rq_affinity_store(struct gendisk *disk, const char *page, size_t count)
#ifdef CONFIG_SMP
struct request_queue *q = disk->queue;
unsigned long val;
unsigned int memflags;

ret = queue_var_store(&val, page, count);
if (ret < 0)
Expand All @@ -421,7 +418,6 @@ queue_rq_affinity_store(struct gendisk *disk, const char *page, size_t count)
* are accessed individually using atomic test_bit operation. So we
* don't grab any lock while updating these flags.
*/
memflags = blk_mq_freeze_queue(q);
if (val == 2) {
blk_queue_flag_set(QUEUE_FLAG_SAME_COMP, q);
blk_queue_flag_set(QUEUE_FLAG_SAME_FORCE, q);
Expand All @@ -432,7 +428,6 @@ queue_rq_affinity_store(struct gendisk *disk, const char *page, size_t count)
blk_queue_flag_clear(QUEUE_FLAG_SAME_COMP, q);
blk_queue_flag_clear(QUEUE_FLAG_SAME_FORCE, q);
}
blk_mq_unfreeze_queue(q, memflags);
#endif
return ret;
}
Expand All @@ -446,11 +441,9 @@ static ssize_t queue_poll_delay_store(struct gendisk *disk, const char *page,
static ssize_t queue_poll_store(struct gendisk *disk, const char *page,
size_t count)
{
unsigned int memflags;
ssize_t ret = count;
struct request_queue *q = disk->queue;

memflags = blk_mq_freeze_queue(q);
if (!(q->limits.features & BLK_FEAT_POLL)) {
ret = -EINVAL;
goto out;
Expand All @@ -459,7 +452,6 @@ static ssize_t queue_poll_store(struct gendisk *disk, const char *page,
pr_info_ratelimited("writes to the poll attribute are ignored.\n");
pr_info_ratelimited("please use driver specific parameters instead.\n");
out:
blk_mq_unfreeze_queue(q, memflags);
return ret;
}

Expand All @@ -472,17 +464,15 @@ static ssize_t queue_io_timeout_show(struct gendisk *disk, char *page)
static ssize_t queue_io_timeout_store(struct gendisk *disk, const char *page,
size_t count)
{
unsigned int val, memflags;
unsigned int val;
int err;
struct request_queue *q = disk->queue;

err = kstrtou32(page, 10, &val);
if (err || val == 0)
return -EINVAL;

memflags = blk_mq_freeze_queue(q);
blk_queue_rq_timeout(q, msecs_to_jiffies(val));
blk_mq_unfreeze_queue(q, memflags);

return count;
}
Expand Down
4 changes: 3 additions & 1 deletion include/linux/backing-dev-defs.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -168,7 +168,9 @@ struct backing_dev_info {
u64 id;
struct rb_node rb_node; /* keyed by ->id */
struct list_head bdi_list;
unsigned long ra_pages; /* max readahead in PAGE_SIZE units */
/* max readahead in PAGE_SIZE units */
unsigned long __data_racy ra_pages;

unsigned long io_pages; /* max allowed IO size */

struct kref refcnt; /* Reference counter for the structure */
Expand Down
2 changes: 1 addition & 1 deletion include/linux/blkdev.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -485,7 +485,7 @@ struct request_queue {
*/
unsigned long queue_flags;

unsigned int rq_timeout;
unsigned int __data_racy rq_timeout;

unsigned int queue_depth;

Expand Down
Loading