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Filename Latest commit message Latest commit date
xiaoshoukui a0a462a0f2 btrfs: fix BUG_ON condition in btrfs_cancel_balance
commit 29eefa6d0d07e185f7bfe9576f91e6dba98189c2 upstream.

Pausing and canceling balance can race to interrupt balance lead to BUG_ON
panic in btrfs_cancel_balance. The BUG_ON condition in btrfs_cancel_balance
does not take this race scenario into account.

However, the race condition has no other side effects. We can fix that.

Reproducing it with panic trace like this:

  kernel BUG at fs/btrfs/volumes.c:4618!
  RIP: 0010:btrfs_cancel_balance+0x5cf/0x6a0
  Call Trace:
   <TASK>
   ? do_nanosleep+0x60/0x120
   ? hrtimer_nanosleep+0xb7/0x1a0
   ? sched_core_clone_cookie+0x70/0x70
   btrfs_ioctl_balance_ctl+0x55/0x70
   btrfs_ioctl+0xa46/0xd20
   __x64_sys_ioctl+0x7d/0xa0
   do_syscall_64+0x38/0x80
   entry_SYSCALL_64_after_hwframe+0x63/0xcd

  Race scenario as follows:
  > mutex_unlock(&fs_info->balance_mutex);
  > --------------------
  > .......issue pause and cancel req in another thread
  > --------------------
  > ret = __btrfs_balance(fs_info);
  >
  > mutex_lock(&fs_info->balance_mutex);
  > if (ret == -ECANCELED && atomic_read(&fs_info->balance_pause_req)) {
  >         btrfs_info(fs_info, "balance: paused");
  >         btrfs_exclop_balance(fs_info, BTRFS_EXCLOP_BALANCE_PAUSED);
  > }

CC: stable@vger.kernel.org # 4.19+
Signed-off-by: xiaoshoukui <xiaoshoukui@ruijie.com.cn>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-08-30 16:27:15 +02:00
arch powerpc/rtas_flash: allow user copy to flash block cache objects 2023-08-30 16:27:15 +02:00
block
certs
crypto
Documentation PM: runtime: Add pm_runtime_get_if_active() 2023-08-30 16:27:12 +02:00
drivers tty: serial: fsl_lpuart: Clear the error flags by writing 1 for lpuart32 platforms 2023-08-30 16:27:15 +02:00
fs btrfs: fix BUG_ON condition in btrfs_cancel_balance 2023-08-30 16:27:15 +02:00
include interconnect: Add helpers for enabling/disabling a path 2023-08-30 16:27:13 +02:00
init
ipc
kernel tracing/probes: Fix to update dynamic data counter if fetcharg uses it 2023-08-30 16:27:14 +02:00
lib
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net net/ncsi: Fix gma flag setting after response 2023-08-30 16:27:14 +02:00
samples
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security
sound ALSA: hda: Fix unhandled register update during auto-suspend period 2023-08-30 16:27:12 +02:00
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Linux kernel
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There are various text files in the Documentation/ subdirectory,
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