linux.git/block, branch vsnprintf

block: avoid to reuse `hctx` not removed from cpuhp callback list

2024-12-18T14:25:37+00:00

If the 'hctx' isn't removed from cpuhp callback list, we can't reuse it,
otherwise use-after-free may be triggered.

Reported-by: kernel test robot 
Closes: https://lore.kernel.org/oe-lkp/202412172217.b906db7c-lkp@intel.com
Tested-by: kernel test robot 
Fixes: 22465bbac53c ("blk-mq: move cpuhp callback registering out of q->sysfs_lock")
Signed-off-by: Ming Lei 
Link: https://lore.kernel.org/r/20241218101617.3275704-3-ming.lei@redhat.com
Signed-off-by: Jens Axboe

block: Revert "block: Fix potential deadlock while freezing queue and acquiring sysfs_lock"

2024-12-18T14:25:37+00:00

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 
Fixes: be26ba96421a ("block: Fix potential deadlock while freezing queue and acquiring sysfs_loc")
Signed-off-by: Ming Lei 
Link: https://lore.kernel.org/r/20241218101617.3275704-2-ming.lei@redhat.com
Signed-off-by: Jens Axboe

block/bdev: use helper for max block size check

2024-12-18T14:22:30+00:00

We already have a helper for checking the limits on the block size
both low and high, just use that.

No functional changes.

Reviewed-by: John Garry 
Signed-off-by: Luis Chamberlain 
Reviewed-by: Keith Busch 
Reviewed-by: Christoph Hellwig 
Link: https://lore.kernel.org/r/20241218020212.3657139-2-mcgrof@kernel.org
Signed-off-by: Jens Axboe

block: Fix potential deadlock while freezing queue and acquiring sysfs_lock

2024-12-13T17:51:58+00:00

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 
Reviewed-by: Ming Lei 
Link: https://lore.kernel.org/r/20241210144222.1066229-1-nilay@linux.ibm.com
Signed-off-by: Jens Axboe

block: Fix queue_iostats_passthrough_show()

2024-12-13T15:09:43+00:00

Make queue_iostats_passthrough_show() report 0/1 in sysfs instead of 0/4.

This patch fixes the following sparse warning:
block/blk-sysfs.c:266:31: warning: incorrect type in argument 1 (different base types)
block/blk-sysfs.c:266:31:    expected unsigned long var
block/blk-sysfs.c:266:31:    got restricted blk_flags_t

Cc: Keith Busch 
Cc: Christoph Hellwig 
Fixes: 110234da18ab ("block: enable passthrough command statistics")
Signed-off-by: Bart Van Assche 
Link: https://lore.kernel.org/r/20241212212941.1268662-4-bvanassche@acm.org
Signed-off-by: Jens Axboe

blk-mq: Clean up blk_mq_requeue_work()

2024-12-13T15:09:43+00:00

Move a statement that occurs in both branches of an if-statement in front
of the if-statement. Fix a typo in a source code comment. No functionality
has been changed.

Reviewed-by: Damien Le Moal 
Cc: Christoph Hellwig 
Signed-off-by: Bart Van Assche 
Reviewed-by: Christoph Hellwig 
Reviewed-by: Nitesh Shetty 
Reviewed-by: Johannes Thumshirn 
Link: https://lore.kernel.org/r/20241212212941.1268662-3-bvanassche@acm.org
Signed-off-by: Jens Axboe

mq-deadline: Remove a local variable

2024-12-13T15:09:43+00:00

Since commit fde02699c242 ("block: mq-deadline: Remove support for zone
write locking"), the local variable 'insert_before' is assigned once and
is used once. Hence remove this local variable.

Reviewed-by: Damien Le Moal 
Cc: Christoph Hellwig 
Signed-off-by: Bart Van Assche 
Reviewed-by: Christoph Hellwig 
Reviewed-by: Nitesh Shetty 
Reviewed-by: Johannes Thumshirn 
Link: https://lore.kernel.org/r/20241212212941.1268662-2-bvanassche@acm.org
Signed-off-by: Jens Axboe

blk-iocost: Avoid using clamp() on inuse in __propagate_weights()

2024-12-12T18:48:14+00:00

After a recent change to clamp() and its variants [1] that increases the
coverage of the check that high is greater than low because it can be
done through inlining, certain build configurations (such as s390
defconfig) fail to build with clang with:

  block/blk-iocost.c:1101:11: error: call to '__compiletime_assert_557' declared with 'error' attribute: clamp() low limit 1 greater than high limit active
   1101 |                 inuse = clamp_t(u32, inuse, 1, active);
        |                         ^
  include/linux/minmax.h:218:36: note: expanded from macro 'clamp_t'
    218 | #define clamp_t(type, val, lo, hi) __careful_clamp(type, val, lo, hi)
        |                                    ^
  include/linux/minmax.h:195:2: note: expanded from macro '__careful_clamp'
    195 |         __clamp_once(type, val, lo, hi, __UNIQUE_ID(v_), __UNIQUE_ID(l_), __UNIQUE_ID(h_))
        |         ^
  include/linux/minmax.h:188:2: note: expanded from macro '__clamp_once'
    188 |         BUILD_BUG_ON_MSG(statically_true(ulo > uhi),                            \
        |         ^

__propagate_weights() is called with an active value of zero in
ioc_check_iocgs(), which results in the high value being less than the
low value, which is undefined because the value returned depends on the
order of the comparisons.

The purpose of this expression is to ensure inuse is not more than
active and at least 1. This could be written more simply with a ternary
expression that uses min(inuse, active) as the condition so that the
value of that condition can be used if it is not zero and one if it is.
Do this conversion to resolve the error and add a comment to deter
people from turning this back into clamp().

Fixes: 7caa47151ab2 ("blkcg: implement blk-iocost")
Link: https://lore.kernel.org/r/34d53778977747f19cce2abb287bb3e6@AcuMS.aculab.com/ [1]
Suggested-by: David Laight 
Reported-by: Linux Kernel Functional Testing 
Closes: https://lore.kernel.org/llvm/CA+G9fYsD7mw13wredcZn0L-KBA3yeoVSTuxnss-AEWMN3ha0cA@mail.gmail.com/
Reported-by: kernel test robot 
Closes: https://lore.kernel.org/oe-kbuild-all/202412120322.3GfVe3vF-lkp@intel.com/
Signed-off-by: Nathan Chancellor 
Acked-by: Tejun Heo 
Signed-off-by: Jens Axboe

block: Make bio_iov_bvec_set() accept pointer to const iov_iter

2024-12-12T15:43:28+00:00

Make bio_iov_bvec_set() accept a pointer to const iov_iter, which means
that we can drop the undesirable casting to struct iov_iter pointer in
blk_rq_map_user_bvec().

Signed-off-by: John Garry 
Reviewed-by: Christoph Hellwig 
Link: https://lore.kernel.org/r/20241202115727.2320401-1-john.g.garry@oracle.com
Signed-off-by: Jens Axboe

block: get wp_offset by bdev_offset_from_zone_start

2024-12-10T20:24:24+00:00

Call bdev_offset_from_zone_start() instead of open-coding it.

Fixes: dd291d77cc90 ("block: Introduce zone write plugging")
Signed-off-by: LongPing Wei 
Reviewed-by: Damien Le Moal 
Reviewed-by: Bart Van Assche 
Link: https://lore.kernel.org/r/20241107020439.1644577-1-weilongping@oppo.com
Signed-off-by: Jens Axboe