linux-toradex.git/block/blk-mq-sysfs.c, branch v6.16-rc4 Linux kernel for Apalis and Colibri modules block: protect hctx attributes/params using q->elevator_lock 2025-03-10T13:31:06+00:00 Nilay Shroff nilay@linux.ibm.com 2025-03-06T09:39:53+00:00 5abba4cebec0a591ca7e7f55701e42cd5dc059af Currently, hctx attributes (nr_tags, nr_reserved_tags, and cpu_list) are protected using `q->sysfs_lock`. However, these attributes can be updated in multiple scenarios: - During the driver's probe method. - When updating nr_hw_queues. - When writing to the sysfs attribute nr_requests, which can modify nr_tags. The nr_requests attribute is already protected using q->elevator_lock, but none of the update paths actually use q->sysfs_lock to protect hctx attributes. So to ensure proper synchronization, replace q->sysfs_lock with q->elevator_lock when reading hctx attributes through sysfs. Additionally, blk_mq_update_nr_hw_queues allocates and updates hctx. The allocation of hctx is protected using q->elevator_lock, however, updating hctx params happens without any protection, so safeguard hctx param update path by also using q->elevator_lock. Signed-off-by: Nilay Shroff <nilay@linux.ibm.com> Link: https://lore.kernel.org/r/20250306093956.2818808-1-nilay@linux.ibm.com [axboe: wrap comment at 80 chars] Signed-off-by: Jens Axboe <axboe@kernel.dk> 
Currently, hctx attributes (nr_tags, nr_reserved_tags, and cpu_list)
are protected using `q->sysfs_lock`. However, these attributes can be
updated in multiple scenarios:
  - During the driver's probe method.
  - When updating nr_hw_queues.
  - When writing to the sysfs attribute nr_requests,
    which can modify nr_tags.
The nr_requests attribute is already protected using q->elevator_lock,
but none of the update paths actually use q->sysfs_lock to protect hctx
attributes. So to ensure proper synchronization, replace q->sysfs_lock
with q->elevator_lock when reading hctx attributes through sysfs.

Additionally, blk_mq_update_nr_hw_queues allocates and updates hctx.
The allocation of hctx is protected using q->elevator_lock, however,
updating hctx params happens without any protection, so safeguard hctx
param update path by also using q->elevator_lock.

Signed-off-by: Nilay Shroff <nilay@linux.ibm.com>
Link: https://lore.kernel.org/r/20250306093956.2818808-1-nilay@linux.ibm.com
[axboe: wrap comment at 80 chars]
Signed-off-by: Jens Axboe <axboe@kernel.dk>
block: fix nr_hw_queue update racing with disk addition/removal 2025-01-29T14:16:47+00:00 Nilay Shroff nilay@linux.ibm.com 2025-01-28T14:34:14+00:00 14ef49657ff3b7156952b2eadcf2e5bafd735795 The nr_hw_queue update could potentially race with disk addtion/removal while registering/unregistering hctx sysfs files. The __blk_mq_update_ nr_hw_queues() runs with q->tag_list_lock held and so to avoid it racing with disk addition/removal we should acquire q->tag_list_lock while registering/unregistering hctx sysfs files. With this patch, blk_mq_sysfs_register() (called during disk addition) and blk_mq_sysfs_unregister() (called during disk removal) now runs with q->tag_list_lock held so that it avoids racing with __blk_mq_update _nr_hw_queues(). Signed-off-by: Nilay Shroff <nilay@linux.ibm.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Hannes Reinecke <hare@suse.de> Link: https://lore.kernel.org/r/20250128143436.874357-3-nilay@linux.ibm.com Signed-off-by: Jens Axboe <axboe@kernel.dk> 
The nr_hw_queue update could potentially race with disk addtion/removal
while registering/unregistering hctx sysfs files. The __blk_mq_update_
nr_hw_queues() runs with q->tag_list_lock held and so to avoid it racing
with disk addition/removal we should acquire q->tag_list_lock while
registering/unregistering hctx sysfs files.

With this patch, blk_mq_sysfs_register() (called during disk addition)
and blk_mq_sysfs_unregister() (called during disk removal) now runs
with q->tag_list_lock held so that it avoids racing with __blk_mq_update
_nr_hw_queues().

Signed-off-by: Nilay Shroff <nilay@linux.ibm.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Link: https://lore.kernel.org/r/20250128143436.874357-3-nilay@linux.ibm.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
block: get rid of request queue ->sysfs_dir_lock 2025-01-29T14:16:47+00:00 Nilay Shroff nilay@linux.ibm.com 2025-01-28T14:34:13+00:00 fe6628608627424fb4a6d4c8d2235822457c5d9c The request queue uses ->sysfs_dir_lock for protecting the addition/ deletion of kobject entries under sysfs while we register/unregister blk-mq. However kobject addition/deletion is already protected with kernfs/sysfs internal synchronization primitives. So use of q->sysfs_ dir_lock seems redundant. Moreover, q->sysfs_dir_lock is also used at few other callsites along with q->sysfs_lock for protecting the addition/deletion of kojects. One such example is when we register with sysfs a set of independent access ranges for a disk. Here as well we could get rid off q->sysfs_ dir_lock and only use q->sysfs_lock. The only variable which q->sysfs_dir_lock appears to protect is q-> mq_sysfs_init_done which is set/unset while registering/unregistering blk-mq with sysfs. But use of q->mq_sysfs_init_done could be easily replaced using queue registered bit QUEUE_FLAG_REGISTERED. So with this patch we remove q->sysfs_dir_lock from each callsite and replace q->mq_sysfs_init_done using QUEUE_FLAG_REGISTERED. Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Nilay Shroff <nilay@linux.ibm.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Link: https://lore.kernel.org/r/20250128143436.874357-2-nilay@linux.ibm.com Signed-off-by: Jens Axboe <axboe@kernel.dk> 
The request queue uses ->sysfs_dir_lock for protecting the addition/
deletion of kobject entries under sysfs while we register/unregister
blk-mq. However kobject addition/deletion is already protected with
kernfs/sysfs internal synchronization primitives. So use of q->sysfs_
dir_lock seems redundant.

Moreover, q->sysfs_dir_lock is also used at few other callsites along
with q->sysfs_lock for protecting the addition/deletion of kojects.
One such example is when we register with sysfs a set of independent
access ranges for a disk. Here as well we could get rid off q->sysfs_
dir_lock and only use q->sysfs_lock.

The only variable which q->sysfs_dir_lock appears to protect is q->
mq_sysfs_init_done which is set/unset while registering/unregistering
blk-mq with sysfs. But use of q->mq_sysfs_init_done could be easily
replaced using queue registered bit QUEUE_FLAG_REGISTERED.

So with this patch we remove q->sysfs_dir_lock from each callsite
and replace q->mq_sysfs_init_done using QUEUE_FLAG_REGISTERED.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nilay Shroff <nilay@linux.ibm.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Link: https://lore.kernel.org/r/20250128143436.874357-2-nilay@linux.ibm.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
block: Revert "block: Fix potential deadlock while freezing queue and acquiring sysfs_lock" 2024-12-18T14:25:37+00:00 Ming Lei ming.lei@redhat.com 2024-12-18T10:16:14+00:00 224749be6c23efe7fb8a030854f4fc5d1dd813b3 This reverts commit be26ba96421ab0a8fa2055ccf7db7832a13c44d2. Commit be26ba96421a ("block: Fix potential deadlock while freezing queue and acquiring sysfs_loc") actually reverts commit 22465bbac53c ("blk-mq: move cpuhp callback registering out of q->sysfs_lock"), and causes the original resctrl lockdep warning. So revert it and we need to fix the issue in another way. Cc: Nilay Shroff <nilay@linux.ibm.com> Fixes: be26ba96421a ("block: Fix potential deadlock while freezing queue and acquiring sysfs_loc") Signed-off-by: Ming Lei <ming.lei@redhat.com> Link: https://lore.kernel.org/r/20241218101617.3275704-2-ming.lei@redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk> 
This reverts commit be26ba96421ab0a8fa2055ccf7db7832a13c44d2.

Commit be26ba96421a ("block: Fix potential deadlock while freezing queue and
acquiring sysfs_loc") actually reverts commit 22465bbac53c ("blk-mq: move cpuhp
callback registering out of q->sysfs_lock"), and causes the original resctrl
lockdep warning.

So revert it and we need to fix the issue in another way.

Cc: Nilay Shroff <nilay@linux.ibm.com>
Fixes: be26ba96421a ("block: Fix potential deadlock while freezing queue and acquiring sysfs_loc")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20241218101617.3275704-2-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
block: Fix potential deadlock while freezing queue and acquiring sysfs_lock 2024-12-13T17:51:58+00:00 Nilay Shroff nilay@linux.ibm.com 2024-12-10T14:41:43+00:00 be26ba96421ab0a8fa2055ccf7db7832a13c44d2 For storing a value to a queue attribute, the queue_attr_store function first freezes the queue (->q_usage_counter(io)) and then acquire ->sysfs_lock. This seems not correct as the usual ordering should be to acquire ->sysfs_lock before freezing the queue. This incorrect ordering causes the following lockdep splat which we are able to reproduce always simply by accessing /sys/kernel/debug file using ls command: [ 57.597146] WARNING: possible circular locking dependency detected [ 57.597154] 6.12.0-10553-gb86545e02e8c #20 Tainted: G W [ 57.597162] ------------------------------------------------------ [ 57.597168] ls/4605 is trying to acquire lock: [ 57.597176] c00000003eb56710 (&mm->mmap_lock){++++}-{4:4}, at: __might_fault+0x58/0xc0 [ 57.597200] but task is already holding lock: [ 57.597207] c0000018e27c6810 (&sb->s_type->i_mutex_key#3){++++}-{4:4}, at: iterate_dir+0x94/0x1d4 [ 57.597226] which lock already depends on the new lock. [ 57.597233] the existing dependency chain (in reverse order) is: [ 57.597241] -> #5 (&sb->s_type->i_mutex_key#3){++++}-{4:4}: [ 57.597255] down_write+0x6c/0x18c [ 57.597264] start_creating+0xb4/0x24c [ 57.597274] debugfs_create_dir+0x2c/0x1e8 [ 57.597283] blk_register_queue+0xec/0x294 [ 57.597292] add_disk_fwnode+0x2e4/0x548 [ 57.597302] brd_alloc+0x2c8/0x338 [ 57.597309] brd_init+0x100/0x178 [ 57.597317] do_one_initcall+0x88/0x3e4 [ 57.597326] kernel_init_freeable+0x3cc/0x6e0 [ 57.597334] kernel_init+0x34/0x1cc [ 57.597342] ret_from_kernel_user_thread+0x14/0x1c [ 57.597350] -> #4 (&q->debugfs_mutex){+.+.}-{4:4}: [ 57.597362] __mutex_lock+0xfc/0x12a0 [ 57.597370] blk_register_queue+0xd4/0x294 [ 57.597379] add_disk_fwnode+0x2e4/0x548 [ 57.597388] brd_alloc+0x2c8/0x338 [ 57.597395] brd_init+0x100/0x178 [ 57.597402] do_one_initcall+0x88/0x3e4 [ 57.597410] kernel_init_freeable+0x3cc/0x6e0 [ 57.597418] kernel_init+0x34/0x1cc [ 57.597426] ret_from_kernel_user_thread+0x14/0x1c [ 57.597434] -> #3 (&q->sysfs_lock){+.+.}-{4:4}: [ 57.597446] __mutex_lock+0xfc/0x12a0 [ 57.597454] queue_attr_store+0x9c/0x110 [ 57.597462] sysfs_kf_write+0x70/0xb0 [ 57.597471] kernfs_fop_write_iter+0x1b0/0x2ac [ 57.597480] vfs_write+0x3dc/0x6e8 [ 57.597488] ksys_write+0x84/0x140 [ 57.597495] system_call_exception+0x130/0x360 [ 57.597504] system_call_common+0x160/0x2c4 [ 57.597516] -> #2 (&q->q_usage_counter(io)#21){++++}-{0:0}: [ 57.597530] __submit_bio+0x5ec/0x828 [ 57.597538] submit_bio_noacct_nocheck+0x1e4/0x4f0 [ 57.597547] iomap_readahead+0x2a0/0x448 [ 57.597556] xfs_vm_readahead+0x28/0x3c [ 57.597564] read_pages+0x88/0x41c [ 57.597571] page_cache_ra_unbounded+0x1ac/0x2d8 [ 57.597580] filemap_get_pages+0x188/0x984 [ 57.597588] filemap_read+0x13c/0x4bc [ 57.597596] xfs_file_buffered_read+0x88/0x17c [ 57.597605] xfs_file_read_iter+0xac/0x158 [ 57.597614] vfs_read+0x2d4/0x3b4 [ 57.597622] ksys_read+0x84/0x144 [ 57.597629] system_call_exception+0x130/0x360 [ 57.597637] system_call_common+0x160/0x2c4 [ 57.597647] -> #1 (mapping.invalidate_lock#2){++++}-{4:4}: [ 57.597661] down_read+0x6c/0x220 [ 57.597669] filemap_fault+0x870/0x100c [ 57.597677] xfs_filemap_fault+0xc4/0x18c [ 57.597684] __do_fault+0x64/0x164 [ 57.597693] __handle_mm_fault+0x1274/0x1dac [ 57.597702] handle_mm_fault+0x248/0x484 [ 57.597711] ___do_page_fault+0x428/0xc0c [ 57.597719] hash__do_page_fault+0x30/0x68 [ 57.597727] do_hash_fault+0x90/0x35c [ 57.597736] data_access_common_virt+0x210/0x220 [ 57.597745] _copy_from_user+0xf8/0x19c [ 57.597754] sel_write_load+0x178/0xd54 [ 57.597762] vfs_write+0x108/0x6e8 [ 57.597769] ksys_write+0x84/0x140 [ 57.597777] system_call_exception+0x130/0x360 [ 57.597785] system_call_common+0x160/0x2c4 [ 57.597794] -> #0 (&mm->mmap_lock){++++}-{4:4}: [ 57.597806] __lock_acquire+0x17cc/0x2330 [ 57.597814] lock_acquire+0x138/0x400 [ 57.597822] __might_fault+0x7c/0xc0 [ 57.597830] filldir64+0xe8/0x390 [ 57.597839] dcache_readdir+0x80/0x2d4 [ 57.597846] iterate_dir+0xd8/0x1d4 [ 57.597855] sys_getdents64+0x88/0x2d4 [ 57.597864] system_call_exception+0x130/0x360 [ 57.597872] system_call_common+0x160/0x2c4 [ 57.597881] other info that might help us debug this: [ 57.597888] Chain exists of: &mm->mmap_lock --> &q->debugfs_mutex --> &sb->s_type->i_mutex_key#3 [ 57.597905] Possible unsafe locking scenario: [ 57.597911] CPU0 CPU1 [ 57.597917] ---- ---- [ 57.597922] rlock(&sb->s_type->i_mutex_key#3); [ 57.597932] lock(&q->debugfs_mutex); [ 57.597940] lock(&sb->s_type->i_mutex_key#3); [ 57.597950] rlock(&mm->mmap_lock); [ 57.597958] *** DEADLOCK *** [ 57.597965] 2 locks held by ls/4605: [ 57.597971] #0: c0000000137c12f8 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0xcc/0x154 [ 57.597989] #1: c0000018e27c6810 (&sb->s_type->i_mutex_key#3){++++}-{4:4}, at: iterate_dir+0x94/0x1d4 Prevent the above lockdep warning by acquiring ->sysfs_lock before freezing the queue while storing a queue attribute in queue_attr_store function. Later, we also found[1] another function __blk_mq_update_nr_ hw_queues where we first freeze queue and then acquire the ->sysfs_lock. So we've also updated lock ordering in __blk_mq_update_nr_hw_queues function and ensured that in all code paths we follow the correct lock ordering i.e. acquire ->sysfs_lock before freezing the queue. [1] https://lore.kernel.org/all/CAFj5m9Ke8+EHKQBs_Nk6hqd=LGXtk4mUxZUN5==ZcCjnZSBwHw@mail.gmail.com/ Reported-by: kjain@linux.ibm.com Fixes: af2814149883 ("block: freeze the queue in queue_attr_store") Tested-by: kjain@linux.ibm.com Cc: hch@lst.de Cc: axboe@kernel.dk Cc: ritesh.list@gmail.com Cc: ming.lei@redhat.com Cc: gjoyce@linux.ibm.com Signed-off-by: Nilay Shroff <nilay@linux.ibm.com> Reviewed-by: Ming Lei <ming.lei@redhat.com> Link: https://lore.kernel.org/r/20241210144222.1066229-1-nilay@linux.ibm.com Signed-off-by: Jens Axboe <axboe@kernel.dk> 
For storing a value to a queue attribute, the queue_attr_store function
first freezes the queue (->q_usage_counter(io)) and then acquire
->sysfs_lock. This seems not correct as the usual ordering should be to
acquire ->sysfs_lock before freezing the queue. This incorrect ordering
causes the following lockdep splat which we are able to reproduce always
simply by accessing /sys/kernel/debug file using ls command:

[   57.597146] WARNING: possible circular locking dependency detected
[   57.597154] 6.12.0-10553-gb86545e02e8c #20 Tainted: G        W
[   57.597162] ------------------------------------------------------
[   57.597168] ls/4605 is trying to acquire lock:
[   57.597176] c00000003eb56710 (&mm->mmap_lock){++++}-{4:4}, at: __might_fault+0x58/0xc0
[   57.597200]
               but task is already holding lock:
[   57.597207] c0000018e27c6810 (&sb->s_type->i_mutex_key#3){++++}-{4:4}, at: iterate_dir+0x94/0x1d4
[   57.597226]
               which lock already depends on the new lock.

[   57.597233]
               the existing dependency chain (in reverse order) is:
[   57.597241]
               -> #5 (&sb->s_type->i_mutex_key#3){++++}-{4:4}:
[   57.597255]        down_write+0x6c/0x18c
[   57.597264]        start_creating+0xb4/0x24c
[   57.597274]        debugfs_create_dir+0x2c/0x1e8
[   57.597283]        blk_register_queue+0xec/0x294
[   57.597292]        add_disk_fwnode+0x2e4/0x548
[   57.597302]        brd_alloc+0x2c8/0x338
[   57.597309]        brd_init+0x100/0x178
[   57.597317]        do_one_initcall+0x88/0x3e4
[   57.597326]        kernel_init_freeable+0x3cc/0x6e0
[   57.597334]        kernel_init+0x34/0x1cc
[   57.597342]        ret_from_kernel_user_thread+0x14/0x1c
[   57.597350]
               -> #4 (&q->debugfs_mutex){+.+.}-{4:4}:
[   57.597362]        __mutex_lock+0xfc/0x12a0
[   57.597370]        blk_register_queue+0xd4/0x294
[   57.597379]        add_disk_fwnode+0x2e4/0x548
[   57.597388]        brd_alloc+0x2c8/0x338
[   57.597395]        brd_init+0x100/0x178
[   57.597402]        do_one_initcall+0x88/0x3e4
[   57.597410]        kernel_init_freeable+0x3cc/0x6e0
[   57.597418]        kernel_init+0x34/0x1cc
[   57.597426]        ret_from_kernel_user_thread+0x14/0x1c
[   57.597434]
               -> #3 (&q->sysfs_lock){+.+.}-{4:4}:
[   57.597446]        __mutex_lock+0xfc/0x12a0
[   57.597454]        queue_attr_store+0x9c/0x110
[   57.597462]        sysfs_kf_write+0x70/0xb0
[   57.597471]        kernfs_fop_write_iter+0x1b0/0x2ac
[   57.597480]        vfs_write+0x3dc/0x6e8
[   57.597488]        ksys_write+0x84/0x140
[   57.597495]        system_call_exception+0x130/0x360
[   57.597504]        system_call_common+0x160/0x2c4
[   57.597516]
               -> #2 (&q->q_usage_counter(io)#21){++++}-{0:0}:
[   57.597530]        __submit_bio+0x5ec/0x828
[   57.597538]        submit_bio_noacct_nocheck+0x1e4/0x4f0
[   57.597547]        iomap_readahead+0x2a0/0x448
[   57.597556]        xfs_vm_readahead+0x28/0x3c
[   57.597564]        read_pages+0x88/0x41c
[   57.597571]        page_cache_ra_unbounded+0x1ac/0x2d8
[   57.597580]        filemap_get_pages+0x188/0x984
[   57.597588]        filemap_read+0x13c/0x4bc
[   57.597596]        xfs_file_buffered_read+0x88/0x17c
[   57.597605]        xfs_file_read_iter+0xac/0x158
[   57.597614]        vfs_read+0x2d4/0x3b4
[   57.597622]        ksys_read+0x84/0x144
[   57.597629]        system_call_exception+0x130/0x360
[   57.597637]        system_call_common+0x160/0x2c4
[   57.597647]
               -> #1 (mapping.invalidate_lock#2){++++}-{4:4}:
[   57.597661]        down_read+0x6c/0x220
[   57.597669]        filemap_fault+0x870/0x100c
[   57.597677]        xfs_filemap_fault+0xc4/0x18c
[   57.597684]        __do_fault+0x64/0x164
[   57.597693]        __handle_mm_fault+0x1274/0x1dac
[   57.597702]        handle_mm_fault+0x248/0x484
[   57.597711]        ___do_page_fault+0x428/0xc0c
[   57.597719]        hash__do_page_fault+0x30/0x68
[   57.597727]        do_hash_fault+0x90/0x35c
[   57.597736]        data_access_common_virt+0x210/0x220
[   57.597745]        _copy_from_user+0xf8/0x19c
[   57.597754]        sel_write_load+0x178/0xd54
[   57.597762]        vfs_write+0x108/0x6e8
[   57.597769]        ksys_write+0x84/0x140
[   57.597777]        system_call_exception+0x130/0x360
[   57.597785]        system_call_common+0x160/0x2c4
[   57.597794]
               -> #0 (&mm->mmap_lock){++++}-{4:4}:
[   57.597806]        __lock_acquire+0x17cc/0x2330
[   57.597814]        lock_acquire+0x138/0x400
[   57.597822]        __might_fault+0x7c/0xc0
[   57.597830]        filldir64+0xe8/0x390
[   57.597839]        dcache_readdir+0x80/0x2d4
[   57.597846]        iterate_dir+0xd8/0x1d4
[   57.597855]        sys_getdents64+0x88/0x2d4
[   57.597864]        system_call_exception+0x130/0x360
[   57.597872]        system_call_common+0x160/0x2c4
[   57.597881]
               other info that might help us debug this:

[   57.597888] Chain exists of:
                 &mm->mmap_lock --> &q->debugfs_mutex --> &sb->s_type->i_mutex_key#3

[   57.597905]  Possible unsafe locking scenario:

[   57.597911]        CPU0                    CPU1
[   57.597917]        ----                    ----
[   57.597922]   rlock(&sb->s_type->i_mutex_key#3);
[   57.597932]                                lock(&q->debugfs_mutex);
[   57.597940]                                lock(&sb->s_type->i_mutex_key#3);
[   57.597950]   rlock(&mm->mmap_lock);
[   57.597958]
                *** DEADLOCK ***

[   57.597965] 2 locks held by ls/4605:
[   57.597971]  #0: c0000000137c12f8 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0xcc/0x154
[   57.597989]  #1: c0000018e27c6810 (&sb->s_type->i_mutex_key#3){++++}-{4:4}, at: iterate_dir+0x94/0x1d4

Prevent the above lockdep warning by acquiring ->sysfs_lock before
freezing the queue while storing a queue attribute in queue_attr_store
function. Later, we also found[1] another function __blk_mq_update_nr_
hw_queues where we first freeze queue and then acquire the ->sysfs_lock.
So we've also updated lock ordering in __blk_mq_update_nr_hw_queues
function and ensured that in all code paths we follow the correct lock
ordering i.e. acquire ->sysfs_lock before freezing the queue.

[1] https://lore.kernel.org/all/CAFj5m9Ke8+EHKQBs_Nk6hqd=LGXtk4mUxZUN5==ZcCjnZSBwHw@mail.gmail.com/

Reported-by: kjain@linux.ibm.com
Fixes: af2814149883 ("block: freeze the queue in queue_attr_store")
Tested-by: kjain@linux.ibm.com
Cc: hch@lst.de
Cc: axboe@kernel.dk
Cc: ritesh.list@gmail.com
Cc: ming.lei@redhat.com
Cc: gjoyce@linux.ibm.com
Signed-off-by: Nilay Shroff <nilay@linux.ibm.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20241210144222.1066229-1-nilay@linux.ibm.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
blk-mq: include <linux/blk-mq.h> in block/blk-mq.h 2023-04-13T12:52:29+00:00 Christoph Hellwig hch@lst.de 2023-04-13T06:40:40+00:00 90110e04f265b95f59fbae09c228c5920b8a302f block/blk-mq.h needs various definitions from <linux/blk-mq.h>, include it there instead of relying on the source files to include both. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Damien Le Moal <dlemoal@kernel.org> Link: https://lore.kernel.org/r/20230413064057.707578-4-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk> 
block/blk-mq.h needs various definitions from <linux/blk-mq.h>,
include it there instead of relying on the source files to include
both.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Link: https://lore.kernel.org/r/20230413064057.707578-4-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
blk-mq: remove blk-mq-tag.h 2023-04-13T12:52:29+00:00 Christoph Hellwig hch@lst.de 2023-04-13T06:40:39+00:00 bebe84ebeec4d030aa65af58376305749762e5a0 blk-mq-tag.h is always included by blk-mq.h, and causes recursive inclusion hell with further changes. Just merge it into blk-mq.h instead. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Damien Le Moal <dlemoal@kernel.org> Link: https://lore.kernel.org/r/20230413064057.707578-3-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk> 
blk-mq-tag.h is always included by blk-mq.h, and causes recursive
inclusion hell with further changes.  Just merge it into blk-mq.h
instead.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Link: https://lore.kernel.org/r/20230413064057.707578-3-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
block: make kobj_type structures constant 2023-02-09T16:38:16+00:00 Thomas Weißschuh linux@weissschuh.net 2023-02-08T04:01:22+00:00 5f6224175fbe4c2b91e303c17af4d4eb5e3a60a7 Since commit ee6d3dd4ed48 ("driver core: make kobj_type constant.") the driver core allows the usage of const struct kobj_type. Take advantage of this to constify the structure definitions to prevent modification at runtime. Signed-off-by: Thomas Weißschuh <linux@weissschuh.net> Link: https://lore.kernel.org/r/20230208-kobj_type-block-v1-1-0b3eafd7d983@weissschuh.net Signed-off-by: Jens Axboe <axboe@kernel.dk> 
Since commit ee6d3dd4ed48 ("driver core: make kobj_type constant.")
the driver core allows the usage of const struct kobj_type.

Take advantage of this to constify the structure definitions to prevent
modification at runtime.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Link: https://lore.kernel.org/r/20230208-kobj_type-block-v1-1-0b3eafd7d983@weissschuh.net
Signed-off-by: Jens Axboe <axboe@kernel.dk>
blk-mq: cleanup unused methods: blk_mq_hw_sysfs_store 2023-01-29T22:18:35+00:00 Zhong Jinghua zhongjinghua@huawei.com 2023-01-28T03:04:19+00:00 b36781034c42f9932bc6305e9a06490d61d9b8ff We found that the blk_mq_hw_sysfs_store interface has no place to use. The object default_hw_ctx_attrs using blk_mq_hw_sysfs_ops only uses the show method and does not use the store method. Since this patch: 4a46f05ebf99 ("blk-mq: move hctx and ctx counters from sysfs to debugfs") moved the store method to debugfs, the store method is not used anymore. So let me do some tiny work to clean up unused code. Signed-off-by: Zhong Jinghua <zhongjinghua@huawei.com> Reviewed-by: Ming Lei <ming.lei@redhat.com> Link: https://lore.kernel.org/r/20230128030419.2780298-1-zhongjinghua@huawei.com Signed-off-by: Jens Axboe <axboe@kernel.dk> 
We found that the blk_mq_hw_sysfs_store interface has no place to use.
The object default_hw_ctx_attrs using blk_mq_hw_sysfs_ops only uses
the show method and does not use the store method.

Since this patch:
4a46f05ebf99 ("blk-mq: move hctx and ctx counters from sysfs to debugfs")
moved the store method to debugfs, the store method is not used anymore.

So let me do some tiny work to clean up unused code.

Signed-off-by: Zhong Jinghua <zhongjinghua@huawei.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20230128030419.2780298-1-zhongjinghua@huawei.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
blk-mq: fix possible memleak when register 'hctx' failed 2022-11-25T13:34:03+00:00 Ye Bin yebin10@huawei.com 2022-11-17T02:29:40+00:00 4b7a21c57b14fbcd0e1729150189e5933f5088e9 There's issue as follows when do fault injection test: unreferenced object 0xffff888132a9f400 (size 512): comm "insmod", pid 308021, jiffies 4324277909 (age 509.733s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 08 f4 a9 32 81 88 ff ff ...........2.... 08 f4 a9 32 81 88 ff ff 00 00 00 00 00 00 00 00 ...2............ backtrace: [<00000000e8952bb4>] kmalloc_node_trace+0x22/0xa0 [<00000000f9980e0f>] blk_mq_alloc_and_init_hctx+0x3f1/0x7e0 [<000000002e719efa>] blk_mq_realloc_hw_ctxs+0x1e6/0x230 [<000000004f1fda40>] blk_mq_init_allocated_queue+0x27e/0x910 [<00000000287123ec>] __blk_mq_alloc_disk+0x67/0xf0 [<00000000a2a34657>] 0xffffffffa2ad310f [<00000000b173f718>] 0xffffffffa2af824a [<0000000095a1dabb>] do_one_initcall+0x87/0x2a0 [<00000000f32fdf93>] do_init_module+0xdf/0x320 [<00000000cbe8541e>] load_module+0x3006/0x3390 [<0000000069ed1bdb>] __do_sys_finit_module+0x113/0x1b0 [<00000000a1a29ae8>] do_syscall_64+0x35/0x80 [<000000009cd878b0>] entry_SYSCALL_64_after_hwframe+0x46/0xb0 Fault injection context as follows: kobject_add blk_mq_register_hctx blk_mq_sysfs_register blk_register_queue device_add_disk null_add_dev.part.0 [null_blk] As 'blk_mq_register_hctx' may already add some objects when failed halfway, but there isn't do fallback, caller don't know which objects add failed. To solve above issue just do fallback when add objects failed halfway in 'blk_mq_register_hctx'. Signed-off-by: Ye Bin <yebin10@huawei.com> Reviewed-by: Ming Lei <ming.lei@redhat.com> Link: https://lore.kernel.org/r/20221117022940.873959-1-yebin@huaweicloud.com Signed-off-by: Jens Axboe <axboe@kernel.dk> 
There's issue as follows when do fault injection test:
unreferenced object 0xffff888132a9f400 (size 512):
  comm "insmod", pid 308021, jiffies 4324277909 (age 509.733s)
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 08 f4 a9 32 81 88 ff ff  ...........2....
    08 f4 a9 32 81 88 ff ff 00 00 00 00 00 00 00 00  ...2............
  backtrace:
    [<00000000e8952bb4>] kmalloc_node_trace+0x22/0xa0
    [<00000000f9980e0f>] blk_mq_alloc_and_init_hctx+0x3f1/0x7e0
    [<000000002e719efa>] blk_mq_realloc_hw_ctxs+0x1e6/0x230
    [<000000004f1fda40>] blk_mq_init_allocated_queue+0x27e/0x910
    [<00000000287123ec>] __blk_mq_alloc_disk+0x67/0xf0
    [<00000000a2a34657>] 0xffffffffa2ad310f
    [<00000000b173f718>] 0xffffffffa2af824a
    [<0000000095a1dabb>] do_one_initcall+0x87/0x2a0
    [<00000000f32fdf93>] do_init_module+0xdf/0x320
    [<00000000cbe8541e>] load_module+0x3006/0x3390
    [<0000000069ed1bdb>] __do_sys_finit_module+0x113/0x1b0
    [<00000000a1a29ae8>] do_syscall_64+0x35/0x80
    [<000000009cd878b0>] entry_SYSCALL_64_after_hwframe+0x46/0xb0

Fault injection context as follows:
 kobject_add
 blk_mq_register_hctx
 blk_mq_sysfs_register
 blk_register_queue
 device_add_disk
 null_add_dev.part.0 [null_blk]

As 'blk_mq_register_hctx' may already add some objects when failed halfway,
but there isn't do fallback, caller don't know which objects add failed.
To solve above issue just do fallback when add objects failed halfway in
'blk_mq_register_hctx'.

Signed-off-by: Ye Bin <yebin10@huawei.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20221117022940.873959-1-yebin@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>