dm cache: Remove unused btracker_nr_writebacks_queued

btracker_nr_writebacks_queued() has been unused since commit
2e63309507c8 ("dm cache policy smq: don't do any writebacks unless IDLE")

Remove i

dm cache: Remove unused btracker_nr_writebacks_queued

btracker_nr_writebacks_queued() has been unused since commit
2e63309507c8 ("dm cache policy smq: don't do any writebacks unless IDLE")

Remove it.

Signed-off-by: Dr. David Alan Gilbert <[email protected]>
Signed-off-by: Mikulas Patocka <[email protected]>

show more ...

dm-cache: fix warnings about duplicate slab caches

The commit 4c39529663b9 adds a warning about duplicate cache names if
CONFIG_DEBUG_VM is selected. These warnings are triggered by the dm-cache
cod

dm-cache: fix warnings about duplicate slab caches

The commit 4c39529663b9 adds a warning about duplicate cache names if
CONFIG_DEBUG_VM is selected. These warnings are triggered by the dm-cache
code.

The dm-cache code allocates a slab cache for each device. This commit
changes it to allocate just one slab cache in the module init function.

Signed-off-by: Mikulas Patocka <[email protected]>
Fixes: 4c39529663b9 ("slab: Warn on duplicate cache names when DEBUG_VM=y")

show more ...

dm: change "unsigned" to "unsigned int"

Signed-off-by: Heinz Mauelshagen <[email protected]>
Signed-off-by: Mike Snitzer <[email protected]>

dm: add missing SPDX-License-Indentifiers

'GPL-2.0-only' is used instead of 'GPL-2.0' because SPDX has
deprecated its use.

Suggested-by: John Wiele <[email protected]>
Signed-off-by: Heinz Mauelsha

dm: add missing SPDX-License-Indentifiers

'GPL-2.0-only' is used instead of 'GPL-2.0' because SPDX has
deprecated its use.

Suggested-by: John Wiele <[email protected]>
Signed-off-by: Heinz Mauelshagen <[email protected]>
Signed-off-by: Mike Snitzer <[email protected]>

show more ...

dm cache: free background tracker's queued work in btracker_destroy

Otherwise the kernel can BUG with:

[ 2245.426978] =============================================================================
[

dm cache: free background tracker's queued work in btracker_destroy

Otherwise the kernel can BUG with:

[ 2245.426978] =============================================================================
[ 2245.435155] BUG bt_work (Tainted: G B W ): Objects remaining in bt_work on __kmem_cache_shutdown()
[ 2245.445233] -----------------------------------------------------------------------------
[ 2245.445233]
[ 2245.454879] Slab 0x00000000b0ce2b30 objects=64 used=2 fp=0x000000000a3c6a4e flags=0x17ffffc0000200(slab|node=0|zone=2|lastcpupid=0x1fffff)
[ 2245.467300] CPU: 7 PID: 10805 Comm: lvm Kdump: loaded Tainted: G B W 6.0.0-rc2 #19
[ 2245.476078] Hardware name: Dell Inc. PowerEdge R7525/0590KW, BIOS 2.5.6 10/06/2021
[ 2245.483646] Call Trace:
[ 2245.486100] <TASK>
[ 2245.488206] dump_stack_lvl+0x34/0x48
[ 2245.491878] slab_err+0x95/0xcd
[ 2245.495028] __kmem_cache_shutdown.cold+0x31/0x136
[ 2245.499821] kmem_cache_destroy+0x49/0x130
[ 2245.503928] btracker_destroy+0x12/0x20 [dm_cache]
[ 2245.508728] smq_destroy+0x15/0x60 [dm_cache_smq]
[ 2245.513435] dm_cache_policy_destroy+0x12/0x20 [dm_cache]
[ 2245.518834] destroy+0xc0/0x110 [dm_cache]
[ 2245.522933] dm_table_destroy+0x5c/0x120 [dm_mod]
[ 2245.527649] __dm_destroy+0x10e/0x1c0 [dm_mod]
[ 2245.532102] dev_remove+0x117/0x190 [dm_mod]
[ 2245.536384] ctl_ioctl+0x1a2/0x290 [dm_mod]
[ 2245.540579] dm_ctl_ioctl+0xa/0x20 [dm_mod]
[ 2245.544773] __x64_sys_ioctl+0x8a/0xc0
[ 2245.548524] do_syscall_64+0x5c/0x90
[ 2245.552104] ? syscall_exit_to_user_mode+0x12/0x30
[ 2245.556897] ? do_syscall_64+0x69/0x90
[ 2245.560648] ? do_syscall_64+0x69/0x90
[ 2245.564394] entry_SYSCALL_64_after_hwframe+0x63/0xcd
[ 2245.569447] RIP: 0033:0x7fe52583ec6b
...
[ 2245.646771] ------------[ cut here ]------------
[ 2245.651395] kmem_cache_destroy bt_work: Slab cache still has objects when called from btracker_destroy+0x12/0x20 [dm_cache]
[ 2245.651408] WARNING: CPU: 7 PID: 10805 at mm/slab_common.c:478 kmem_cache_destroy+0x128/0x130

Found using: lvm2-testsuite --only "cache-single-split.sh"

Ben bisected and found that commit 0495e337b703 ("mm/slab_common:
Deleting kobject in kmem_cache_destroy() without holding
slab_mutex/cpu_hotplug_lock") first exposed dm-cache's incomplete
cleanup of its background tracker work objects.

Reported-by: Benjamin Marzinski <[email protected]>
Tested-by: Benjamin Marzinski <[email protected]>
Cc: [email protected] # 6.0+
Signed-off-by: Joe Thornber <[email protected]>
Signed-off-by: Mike Snitzer <[email protected]>

show more ...

dm cache background tracker: fix sparse warning

Fix drivers/md/dm-cache-background-tracker.c:169:16: warning: symbol
'alloc_work' was not declared. Should it be static?

Signed-off-by: Mike Snitzer

dm cache background tracker: fix sparse warning

Fix drivers/md/dm-cache-background-tracker.c:169:16: warning: symbol
'alloc_work' was not declared. Should it be static?

Signed-off-by: Mike Snitzer <[email protected]>

show more ...

dm cache background tracker: limit amount of background work that may be issued at once

On large systems the cache policy can be over enthusiastic and queue far
too much dirty data to be written bac

dm cache background tracker: limit amount of background work that may be issued at once

On large systems the cache policy can be over enthusiastic and queue far
too much dirty data to be written back. This consumes memory.

Signed-off-by: Joe Thornber <[email protected]>
Signed-off-by: Mike Snitzer <[email protected]>

show more ...

dm cache: handle kmalloc failure allocating background_tracker struct

Currently there is no kmalloc failure check on the allocation of
the background_tracker struct in btracker_create(), and so a NU

dm cache: handle kmalloc failure allocating background_tracker struct

Currently there is no kmalloc failure check on the allocation of
the background_tracker struct in btracker_create(), and so a NULL return
will lead to a NULL pointer dereference. Add a NULL check.

Detected by CoverityScan, CID#1416587 ("Dereference null return value")

Fixes: b29d4986d ("dm cache: significant rework to leverage dm-bio-prison-v2")
Signed-off-by: Colin Ian King <[email protected]>
Signed-off-by: Mike Snitzer <[email protected]>

show more ...

dm cache: significant rework to leverage dm-bio-prison-v2

The cache policy interfaces have been updated to work well with the new
bio-prison v2 interface's ability to queue work immediately (promoti

dm cache: significant rework to leverage dm-bio-prison-v2

The cache policy interfaces have been updated to work well with the new
bio-prison v2 interface's ability to queue work immediately (promotion,
demotion, etc) -- overriding benefit being reduced latency on processing
IO through the cache. Previously such work would be left for the DM
cache core to queue on various lists and then process in batches later
-- this caused a serious delay in latency for IO driven by the cache.

The background tracker code was factored out so that all cache policies
can make use of it.

Also, the "cleaner" policy has been removed and is now a variant of the
smq policy that simply disallows migrations.

Signed-off-by: Joe Thornber <[email protected]>
Signed-off-by: Mike Snitzer <[email protected]>

show more ...