linux-toradex.git/lib/sbitmap.c, branch v5.9-rc6 Linux kernel for Apalis and Colibri modules sbitmap: Consider cleared bits in sbitmap_bitmap_show() 2020-07-01T16:53:00+00:00 John Garry john.garry@huawei.com 2020-07-01T08:06:25+00:00 6bf0eb5504529cdf50a24135e4c4442a093c06d6 sbitmap works by maintaining separate bitmaps of set and cleared bits. The set bits are cleared in a batch, to save the burden of continuously locking the "word" map to unset. sbitmap_bitmap_show() only shows the set bits (in "word"), which is not too much use, so mask out the cleared bits. Fixes: ea86ea2cdced ("sbitmap: ammortize cost of clearing bits") Signed-off-by: John Garry <john.garry@huawei.com> Signed-off-by: Jens Axboe <axboe@kernel.dk> 
sbitmap works by maintaining separate bitmaps of set and cleared bits.
The set bits are cleared in a batch, to save the burden of continuously
locking the "word" map to unset.

sbitmap_bitmap_show() only shows the set bits (in "word"), which is not
too much use, so mask out the cleared bits.

Fixes: ea86ea2cdced ("sbitmap: ammortize cost of clearing bits")
Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
sbitmap: only queue kyber's wait callback if not already active 2019-12-20T23:51:54+00:00 David Jeffery djeffery@redhat.com 2019-12-17T16:00:24+00:00 df034c93f15ee71df231ff9fe311d27ff08a2a52 Under heavy loads where the kyber I/O scheduler hits the token limits for its scheduling domains, kyber can become stuck. When active requests complete, kyber may not be woken up leaving the I/O requests in kyber stuck. This stuck state is due to a race condition with kyber and the sbitmap functions it uses to run a callback when enough requests have completed. The running of a sbt_wait callback can race with the attempt to insert the sbt_wait. Since sbitmap_del_wait_queue removes the sbt_wait from the list first then sets the sbq field to NULL, kyber can see the item as not on a list but the call to sbitmap_add_wait_queue will see sbq as non-NULL. This results in the sbt_wait being inserted onto the wait list but ws_active doesn't get incremented. So the sbitmap queue does not know there is a waiter on a wait list. Since sbitmap doesn't think there is a waiter, kyber may never be informed that there are domain tokens available and the I/O never advances. With the sbt_wait on a wait list, kyber believes it has an active waiter so cannot insert a new waiter when reaching the domain's full state. This race can be fixed by only adding the sbt_wait to the queue if the sbq field is NULL. If sbq is not NULL, there is already an action active which will trigger the re-running of kyber. Let it run and add the sbt_wait to the wait list if still needing to wait. Reviewed-by: Omar Sandoval <osandov@fb.com> Signed-off-by: David Jeffery <djeffery@redhat.com> Reported-by: John Pittman <jpittman@redhat.com> Tested-by: John Pittman <jpittman@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk> 
Under heavy loads where the kyber I/O scheduler hits the token limits for
its scheduling domains, kyber can become stuck.  When active requests
complete, kyber may not be woken up leaving the I/O requests in kyber
stuck.

This stuck state is due to a race condition with kyber and the sbitmap
functions it uses to run a callback when enough requests have completed.
The running of a sbt_wait callback can race with the attempt to insert the
sbt_wait.  Since sbitmap_del_wait_queue removes the sbt_wait from the list
first then sets the sbq field to NULL, kyber can see the item as not on a
list but the call to sbitmap_add_wait_queue will see sbq as non-NULL. This
results in the sbt_wait being inserted onto the wait list but ws_active
doesn't get incremented.  So the sbitmap queue does not know there is a
waiter on a wait list.

Since sbitmap doesn't think there is a waiter, kyber may never be
informed that there are domain tokens available and the I/O never advances.
With the sbt_wait on a wait list, kyber believes it has an active waiter
so cannot insert a new waiter when reaching the domain's full state.

This race can be fixed by only adding the sbt_wait to the queue if the
sbq field is NULL.  If sbq is not NULL, there is already an action active
which will trigger the re-running of kyber.  Let it run and add the
sbt_wait to the wait list if still needing to wait.

Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Jeffery <djeffery@redhat.com>
Reported-by: John Pittman <jpittman@redhat.com>
Tested-by: John Pittman <jpittman@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
sbitmap: Delete sbitmap_any_bit_clear() 2019-11-13T19:50:40+00:00 John Garry john.garry@huawei.com 2019-11-13T17:27:22+00:00 708edafa883186f55b24fa0c380242b5282f9105 Since the only caller of this function has been deleted, delete this one also. Signed-off-by: John Garry <john.garry@huawei.com> Signed-off-by: Jens Axboe <axboe@kernel.dk> 
Since the only caller of this function has been deleted, delete this one
also.

Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
sbitmap: Replace cmpxchg with xchg 2019-07-01T17:57:12+00:00 Pavel Begunkov asml.silence@gmail.com 2019-05-23T15:39:16+00:00 417232880c8a646739dbf4666a231505a1917fcb cmpxchg() with an immediate value could be replaced with less expensive xchg(). The same true if new value don't _depend_ on the old one. In the second block, atomic_cmpxchg() return value isn't checked, so after atomic_cmpxchg() -> atomic_xchg() conversion it could be replaced with atomic_set(). Comparison with atomic_read() in the second chunk was left as an optimisation (if that was the initial intention). Reviewed-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk> 
cmpxchg() with an immediate value could be replaced with less expensive
xchg(). The same true if new value don't _depend_ on the old one.

In the second block, atomic_cmpxchg() return value isn't checked, so
after atomic_cmpxchg() ->  atomic_xchg() conversion it could be replaced
with atomic_set(). Comparison with atomic_read() in the second chunk was
left as an optimisation (if that was the initial intention).

Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 328 2019-06-05T15:37:06+00:00 Thomas Gleixner tglx@linutronix.de 2019-05-29T23:57:42+00:00 0fc479b1ad6358d2440faf79a43d422065b77dc0 Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license v2 as published by the free software foundation this program is distributed in the hope that it will be useful but without any warranty without even the implied warranty of merchantability or fitness for a particular purpose see the gnu general public license for more details you should have received a copy of the gnu general public license along with this program if not see https www gnu org licenses extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 2 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Alexios Zavras <alexios.zavras@intel.com> Reviewed-by: Armijn Hemel <armijn@tjaldur.nl> Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Allison Randal <allison@lohutok.net> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190530000435.923873561@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
Based on 1 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license v2 as published
  by the free software foundation this program is distributed in the
  hope that it will be useful but without any warranty without even
  the implied warranty of merchantability or fitness for a particular
  purpose see the gnu general public license for more details you
  should have received a copy of the gnu general public license along
  with this program if not see https www gnu org licenses

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 2 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Alexios Zavras <alexios.zavras@intel.com>
Reviewed-by: Armijn Hemel <armijn@tjaldur.nl>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190530000435.923873561@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
sbitmap: fix improper use of smp_mb__before_atomic() 2019-05-23T16:25:26+00:00 Andrea Parri andrea.parri@amarulasolutions.com 2019-05-20T17:23:57+00:00 a0934fd2b1208458e55fc4b48f55889809fce666 This barrier only applies to the read-modify-write operations; in particular, it does not apply to the atomic_set() primitive. Replace the barrier with an smp_mb(). Fixes: 6c0ca7ae292ad ("sbitmap: fix wakeup hang after sbq resize") Cc: stable@vger.kernel.org Reported-by: "Paul E. McKenney" <paulmck@linux.ibm.com> Reported-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Andrea Parri <andrea.parri@amarulasolutions.com> Reviewed-by: Ming Lei <ming.lei@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Omar Sandoval <osandov@fb.com> Cc: Ming Lei <ming.lei@redhat.com> Cc: linux-block@vger.kernel.org Cc: "Paul E. McKenney" <paulmck@linux.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Jens Axboe <axboe@kernel.dk> 
This barrier only applies to the read-modify-write operations; in
particular, it does not apply to the atomic_set() primitive.

Replace the barrier with an smp_mb().

Fixes: 6c0ca7ae292ad ("sbitmap: fix wakeup hang after sbq resize")
Cc: stable@vger.kernel.org
Reported-by: "Paul E. McKenney" <paulmck@linux.ibm.com>
Reported-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrea Parri <andrea.parri@amarulasolutions.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: linux-block@vger.kernel.org
Cc: "Paul E. McKenney" <paulmck@linux.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
sbitmap: order READ/WRITE freed instance and setting clear bit 2019-03-25T19:05:47+00:00 Ming Lei ming.lei@redhat.com 2019-03-22T01:13:51+00:00 e6d1fa584e0dd9bfebaf345e9feea588cf75ead2 Inside sbitmap_queue_clear(), once the clear bit is set, it will be visiable to allocation path immediately. Meantime READ/WRITE on old associated instance(such as request in case of blk-mq) may be out-of-order with the setting clear bit, so race with re-allocation may be triggered. Adds one memory barrier for ordering READ/WRITE of the freed associated instance with setting clear bit for avoiding race with re-allocation. The following kernel oops triggerd by block/006 on aarch64 may be fixed: [ 142.330954] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000330 [ 142.338794] Mem abort info: [ 142.341554] ESR = 0x96000005 [ 142.344632] Exception class = DABT (current EL), IL = 32 bits [ 142.350500] SET = 0, FnV = 0 [ 142.353544] EA = 0, S1PTW = 0 [ 142.356678] Data abort info: [ 142.359528] ISV = 0, ISS = 0x00000005 [ 142.363343] CM = 0, WnR = 0 [ 142.366305] user pgtable: 64k pages, 48-bit VAs, pgdp = 000000002a3c51c0 [ 142.372983] [0000000000000330] pgd=0000000000000000, pud=0000000000000000 [ 142.379777] Internal error: Oops: 96000005 [#1] SMP [ 142.384613] Modules linked in: null_blk ib_isert iscsi_target_mod ib_srpt target_core_mod ib_srp scsi_transport_srp vfat fat rpcrdma sunrpc rdma_ucm ib_iser rdma_cm iw_cm libiscsi ib_umad scsi_transport_iscsi ib_ipoib ib_cm mlx5_ib ib_uverbs ib_core sbsa_gwdt crct10dif_ce ghash_ce ipmi_ssif sha2_ce ipmi_devintf sha256_arm64 sg sha1_ce ipmi_msghandler ip_tables xfs libcrc32c mlx5_core sdhci_acpi mlxfw ahci_platform at803x sdhci libahci_platform qcom_emac mmc_core hdma hdma_mgmt i2c_dev [last unloaded: null_blk] [ 142.429753] CPU: 7 PID: 1983 Comm: fio Not tainted 5.0.0.cki #2 [ 142.449458] pstate: 00400005 (nzcv daif +PAN -UAO) [ 142.454239] pc : __blk_mq_free_request+0x4c/0xa8 [ 142.458830] lr : blk_mq_free_request+0xec/0x118 [ 142.463344] sp : ffff00003360f6a0 [ 142.466646] x29: ffff00003360f6a0 x28: ffff000010e70000 [ 142.471941] x27: ffff801729a50048 x26: 0000000000010000 [ 142.477232] x25: ffff00003360f954 x24: ffff7bdfff021440 [ 142.482529] x23: 0000000000000000 x22: 00000000ffffffff [ 142.487830] x21: ffff801729810000 x20: 0000000000000000 [ 142.493123] x19: ffff801729a50000 x18: 0000000000000000 [ 142.498413] x17: 0000000000000000 x16: 0000000000000001 [ 142.503709] x15: 00000000000000ff x14: ffff7fe000000000 [ 142.509003] x13: ffff8017dcde09a0 x12: 0000000000000000 [ 142.514308] x11: 0000000000000001 x10: 0000000000000008 [ 142.519597] x9 : ffff8017dcde09a0 x8 : 0000000000002000 [ 142.524889] x7 : ffff8017dcde0a00 x6 : 000000015388f9be [ 142.530187] x5 : 0000000000000001 x4 : 0000000000000000 [ 142.535478] x3 : 0000000000000000 x2 : 0000000000000000 [ 142.540777] x1 : 0000000000000001 x0 : ffff00001041b194 [ 142.546071] Process fio (pid: 1983, stack limit = 0x000000006460a0ea) [ 142.552500] Call trace: [ 142.554926] __blk_mq_free_request+0x4c/0xa8 [ 142.559181] blk_mq_free_request+0xec/0x118 [ 142.563352] blk_mq_end_request+0xfc/0x120 [ 142.567444] end_cmd+0x3c/0xa8 [null_blk] [ 142.571434] null_complete_rq+0x20/0x30 [null_blk] [ 142.576194] blk_mq_complete_request+0x108/0x148 [ 142.580797] null_handle_cmd+0x1d4/0x718 [null_blk] [ 142.585662] null_queue_rq+0x60/0xa8 [null_blk] [ 142.590171] blk_mq_try_issue_directly+0x148/0x280 [ 142.594949] blk_mq_try_issue_list_directly+0x9c/0x108 [ 142.600064] blk_mq_sched_insert_requests+0xb0/0xd0 [ 142.604926] blk_mq_flush_plug_list+0x16c/0x2a0 [ 142.609441] blk_flush_plug_list+0xec/0x118 [ 142.613608] blk_finish_plug+0x3c/0x4c [ 142.617348] blkdev_direct_IO+0x3b4/0x428 [ 142.621336] generic_file_read_iter+0x84/0x180 [ 142.625761] blkdev_read_iter+0x50/0x78 [ 142.629579] aio_read.isra.6+0xf8/0x190 [ 142.633409] __io_submit_one.isra.8+0x148/0x738 [ 142.637912] io_submit_one.isra.9+0x88/0xb8 [ 142.642078] __arm64_sys_io_submit+0xe0/0x238 [ 142.646428] el0_svc_handler+0xa0/0x128 [ 142.650238] el0_svc+0x8/0xc [ 142.653104] Code: b9402a63 f9000a7f 3100047f 540000a0 (f9419a81) [ 142.659202] ---[ end trace 467586bc175eb09d ]--- Fixes: ea86ea2cdced20057da ("sbitmap: ammortize cost of clearing bits") Reported-and-bisected_and_tested-by: Yi Zhang <yi.zhang@redhat.com> Cc: Yi Zhang <yi.zhang@redhat.com> Cc: "jianchao.wang" <jianchao.w.wang@oracle.com> Reviewed-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk> 
Inside sbitmap_queue_clear(), once the clear bit is set, it will be
visiable to allocation path immediately. Meantime READ/WRITE on old
associated instance(such as request in case of blk-mq) may be
out-of-order with the setting clear bit, so race with re-allocation
may be triggered.

Adds one memory barrier for ordering READ/WRITE of the freed associated
instance with setting clear bit for avoiding race with re-allocation.

The following kernel oops triggerd by block/006 on aarch64 may be fixed:

[  142.330954] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000330
[  142.338794] Mem abort info:
[  142.341554]   ESR = 0x96000005
[  142.344632]   Exception class = DABT (current EL), IL = 32 bits
[  142.350500]   SET = 0, FnV = 0
[  142.353544]   EA = 0, S1PTW = 0
[  142.356678] Data abort info:
[  142.359528]   ISV = 0, ISS = 0x00000005
[  142.363343]   CM = 0, WnR = 0
[  142.366305] user pgtable: 64k pages, 48-bit VAs, pgdp = 000000002a3c51c0
[  142.372983] [0000000000000330] pgd=0000000000000000, pud=0000000000000000
[  142.379777] Internal error: Oops: 96000005 [#1] SMP
[  142.384613] Modules linked in: null_blk ib_isert iscsi_target_mod ib_srpt target_core_mod ib_srp scsi_transport_srp vfat fat rpcrdma sunrpc rdma_ucm ib_iser rdma_cm iw_cm libiscsi ib_umad scsi_transport_iscsi ib_ipoib ib_cm mlx5_ib ib_uverbs ib_core sbsa_gwdt crct10dif_ce ghash_ce ipmi_ssif sha2_ce ipmi_devintf sha256_arm64 sg sha1_ce ipmi_msghandler ip_tables xfs libcrc32c mlx5_core sdhci_acpi mlxfw ahci_platform at803x sdhci libahci_platform qcom_emac mmc_core hdma hdma_mgmt i2c_dev [last unloaded: null_blk]
[  142.429753] CPU: 7 PID: 1983 Comm: fio Not tainted 5.0.0.cki #2
[  142.449458] pstate: 00400005 (nzcv daif +PAN -UAO)
[  142.454239] pc : __blk_mq_free_request+0x4c/0xa8
[  142.458830] lr : blk_mq_free_request+0xec/0x118
[  142.463344] sp : ffff00003360f6a0
[  142.466646] x29: ffff00003360f6a0 x28: ffff000010e70000
[  142.471941] x27: ffff801729a50048 x26: 0000000000010000
[  142.477232] x25: ffff00003360f954 x24: ffff7bdfff021440
[  142.482529] x23: 0000000000000000 x22: 00000000ffffffff
[  142.487830] x21: ffff801729810000 x20: 0000000000000000
[  142.493123] x19: ffff801729a50000 x18: 0000000000000000
[  142.498413] x17: 0000000000000000 x16: 0000000000000001
[  142.503709] x15: 00000000000000ff x14: ffff7fe000000000
[  142.509003] x13: ffff8017dcde09a0 x12: 0000000000000000
[  142.514308] x11: 0000000000000001 x10: 0000000000000008
[  142.519597] x9 : ffff8017dcde09a0 x8 : 0000000000002000
[  142.524889] x7 : ffff8017dcde0a00 x6 : 000000015388f9be
[  142.530187] x5 : 0000000000000001 x4 : 0000000000000000
[  142.535478] x3 : 0000000000000000 x2 : 0000000000000000
[  142.540777] x1 : 0000000000000001 x0 : ffff00001041b194
[  142.546071] Process fio (pid: 1983, stack limit = 0x000000006460a0ea)
[  142.552500] Call trace:
[  142.554926]  __blk_mq_free_request+0x4c/0xa8
[  142.559181]  blk_mq_free_request+0xec/0x118
[  142.563352]  blk_mq_end_request+0xfc/0x120
[  142.567444]  end_cmd+0x3c/0xa8 [null_blk]
[  142.571434]  null_complete_rq+0x20/0x30 [null_blk]
[  142.576194]  blk_mq_complete_request+0x108/0x148
[  142.580797]  null_handle_cmd+0x1d4/0x718 [null_blk]
[  142.585662]  null_queue_rq+0x60/0xa8 [null_blk]
[  142.590171]  blk_mq_try_issue_directly+0x148/0x280
[  142.594949]  blk_mq_try_issue_list_directly+0x9c/0x108
[  142.600064]  blk_mq_sched_insert_requests+0xb0/0xd0
[  142.604926]  blk_mq_flush_plug_list+0x16c/0x2a0
[  142.609441]  blk_flush_plug_list+0xec/0x118
[  142.613608]  blk_finish_plug+0x3c/0x4c
[  142.617348]  blkdev_direct_IO+0x3b4/0x428
[  142.621336]  generic_file_read_iter+0x84/0x180
[  142.625761]  blkdev_read_iter+0x50/0x78
[  142.629579]  aio_read.isra.6+0xf8/0x190
[  142.633409]  __io_submit_one.isra.8+0x148/0x738
[  142.637912]  io_submit_one.isra.9+0x88/0xb8
[  142.642078]  __arm64_sys_io_submit+0xe0/0x238
[  142.646428]  el0_svc_handler+0xa0/0x128
[  142.650238]  el0_svc+0x8/0xc
[  142.653104] Code: b9402a63 f9000a7f 3100047f 540000a0 (f9419a81)
[  142.659202] ---[ end trace 467586bc175eb09d ]---

Fixes: ea86ea2cdced20057da ("sbitmap: ammortize cost of clearing bits")
Reported-and-bisected_and_tested-by: Yi Zhang <yi.zhang@redhat.com>
Cc: Yi Zhang <yi.zhang@redhat.com>
Cc: "jianchao.wang" <jianchao.w.wang@oracle.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
sbitmap: Protect swap_lock from hardirq 2019-01-15T04:29:57+00:00 Ming Lei ming.lei@redhat.com 2019-01-15T03:59:52+00:00 fe76fc6aaf538df27708ffa3e5d549a6c8e16142 Because we may call blk_mq_get_driver_tag() directly from blk_mq_dispatch_rq_list() without holding any lock, then HARDIRQ may come and the above DEADLOCK is triggered. Commit ab53dcfb3e7b ("sbitmap: Protect swap_lock from hardirq") tries to fix this issue by using 'spin_lock_bh', which isn't enough because we complete request from hardirq context direclty in case of multiqueue. Cc: Clark Williams <williams@redhat.com> Fixes: ab53dcfb3e7b ("sbitmap: Protect swap_lock from hardirq") Cc: Jens Axboe <axboe@kernel.dk> Cc: Ming Lei <ming.lei@redhat.com> Cc: Guenter Roeck <linux@roeck-us.net> Cc: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 
Because we may call blk_mq_get_driver_tag() directly from
blk_mq_dispatch_rq_list() without holding any lock, then HARDIRQ may
come and the above DEADLOCK is triggered.

Commit ab53dcfb3e7b ("sbitmap: Protect swap_lock from hardirq") tries to
fix this issue by using 'spin_lock_bh', which isn't enough because we
complete request from hardirq context direclty in case of multiqueue.

Cc: Clark Williams <williams@redhat.com>
Fixes: ab53dcfb3e7b ("sbitmap: Protect swap_lock from hardirq")
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
sbitmap: Protect swap_lock from softirqs 2019-01-14T19:31:18+00:00 Steven Rostedt (VMware) rostedt@goodmis.org 2019-01-14T17:25:40+00:00 3719876809e745b9db5293d418600c194bbf5c23 The swap_lock used by sbitmap has a chain with locks taken from softirq, but the swap_lock is not protected from being preempted by softirqs. A chain exists of: sbq->ws[i].wait -> dispatch_wait_lock -> swap_lock Where the sbq->ws[i].wait lock can be taken from softirq context, which means all locks below it in the chain must also be protected from softirqs. Reported-by: Clark Williams <williams@redhat.com> Fixes: 58ab5e32e6fd ("sbitmap: silence bogus lockdep IRQ warning") Fixes: ea86ea2cdced ("sbitmap: amortize cost of clearing bits") Cc: Jens Axboe <axboe@kernel.dk> Cc: Ming Lei <ming.lei@redhat.com> Cc: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> 
The swap_lock used by sbitmap has a chain with locks taken from softirq,
but the swap_lock is not protected from being preempted by softirqs.

A chain exists of:

 sbq->ws[i].wait -> dispatch_wait_lock -> swap_lock

Where the sbq->ws[i].wait lock can be taken from softirq context, which
means all locks below it in the chain must also be protected from
softirqs.

Reported-by: Clark Williams <williams@redhat.com>
Fixes: 58ab5e32e6fd ("sbitmap: silence bogus lockdep IRQ warning")
Fixes: ea86ea2cdced ("sbitmap: amortize cost of clearing bits")
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
sbitmap: add helpers for add/del wait queue handling 2018-12-20T19:17:05+00:00 Jens Axboe axboe@kernel.dk 2018-12-20T15:49:00+00:00 9f6b7ef6c3ebe35be77b0ae3cf12e4d25ae80420 After commit 5d2ee7122c73, users of sbitmap that need wait queue handling must use the provided helpers. But we only added prepare_to_wait()/finish_wait() style helpers, add the equivalent add_wait_queue/list_del wrappers as we.. This is needed to ensure kyber plays by the sbitmap waitqueue rules. Tested-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk> 
After commit 5d2ee7122c73, users of sbitmap that need wait queue
handling must use the provided helpers. But we only added
prepare_to_wait()/finish_wait() style helpers, add the equivalent
add_wait_queue/list_del wrappers as we..

This is needed to ensure kyber plays by the sbitmap waitqueue
rules.

Tested-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>