linux_dsm_epyc7002/drivers/block
Minchan Kim 08eee69fcf zram: remove init_lock in zram_make_request
Admin could reset zram during I/O operation going on so we have used
zram->init_lock as read-side lock in I/O path to prevent sudden zram
meta freeing.

However, the init_lock is really troublesome.  We can't do call
zram_meta_alloc under init_lock due to lockdep splat because
zram_rw_page is one of the function under reclaim path and hold it as
read_lock while other places in process context hold it as write_lock.
So, we have used allocation out of the lock to avoid lockdep warn but
it's not good for readability and fainally, I met another lockdep splat
between init_lock and cpu_hotplug from kmem_cache_destroy during working
zsmalloc compaction.  :(

Yes, the ideal is to remove horrible init_lock of zram in rw path.  This
patch removes it in rw path and instead, add atomic refcount for meta
lifetime management and completion to free meta in process context.
It's important to free meta in process context because some of resource
destruction needs mutex lock, which could be held if we releases the
resource in reclaim context so it's deadlock, again.

As a bonus, we could remove init_done check in rw path because
zram_meta_get will do a role for it, instead.

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Ganesh Mahendran <opensource.ganesh@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-02-12 18:54:12 -08:00
..
aoe block: remove artifical max_hw_sectors cap 2014-10-21 14:02:54 -06:00
drbd Merge branch 'for-3.19/drivers' of git://git.kernel.dk/linux-block 2014-12-13 14:22:26 -08:00
mtip32xx blk-mq: add a 'list' parameter to ->queue_rq() 2014-10-29 11:14:52 -06:00
paride Merge branch 'for-3.18/core' of git://git.kernel.dk/linux-block 2014-10-18 11:53:51 -07:00
rsxx block/rsxx: use generic io stats accounting functions to simplify io stat accounting 2014-11-24 08:05:18 -07:00
xen-blkback xen-blkback: safely unmap grants in case they are still in use 2015-01-28 14:03:16 +00:00
zram zram: remove init_lock in zram_make_request 2015-02-12 18:54:12 -08:00
amiflop.c block: drop owner assignment from platform_drivers 2014-10-20 16:20:18 +02:00
ataflop.c Merge branch 'for-3.16/core' of git://git.kernel.dk/linux-block into next 2014-06-02 09:29:34 -07:00
brd.c brd: add ram disk visibility option 2014-08-21 20:42:01 -05:00
cciss_cmd.h cciss: use new doorbell-bit-5 reset method 2011-05-06 08:23:55 -06:00
cciss_scsi.c cciss: switch to ->show_info() 2013-04-09 14:13:19 -04:00
cciss_scsi.h cciss: add cciss_tape_cmds module paramter 2011-05-06 08:23:59 -06:00
cciss.c block: use pci_zalloc_consistent 2014-08-08 15:57:28 -07:00
cciss.h cciss: Adds simple mode functionality 2011-08-08 11:40:15 +02:00
cpqarray.c cpqarray: fix info leak in ida_locked_ioctl() 2013-09-24 17:00:26 -07:00
cpqarray.h
cryptoloop.c move linux/loop.h to drivers/block 2013-06-29 12:46:45 +04:00
DAC960.c block: use pci_zalloc_consistent 2014-08-08 15:57:28 -07:00
DAC960.h
floppy.c Merge branch 'for-jens' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/linux-block into for-linus 2014-06-18 10:30:22 -07:00
hd.c block: hd: remove deprecated IRQF_DISABLED 2014-10-01 08:16:07 -06:00
ida_cmd.h
ida_ioctl.h
Kconfig zram: promote zram from staging 2014-01-30 16:56:55 -08:00
loop.c Merge branch 'sched/urgent' into sched/core, to avoid conflicts 2014-05-07 13:15:46 +02:00
loop.h move linux/loop.h to drivers/block 2013-06-29 12:46:45 +04:00
Makefile zram: promote zram from staging 2014-01-30 16:56:55 -08:00
mg_disk.c block: drop owner assignment from platform_drivers 2014-10-20 16:20:18 +02:00
nbd.c block: disable entropy contributions for nonrot devices 2014-10-04 10:55:32 -06:00
null_blk.c block: fix checking return value of blk_mq_init_queue 2015-01-02 10:32:02 -07:00
nvme-core.c NVMe: cq_vector should be signed 2015-01-15 15:19:10 -07:00
nvme-scsi.c Merge branch 'for-3.19/drivers' of git://git.kernel.dk/linux-block 2014-12-13 14:22:26 -08:00
osdblk.c block: replace strict_strtoul() with kstrtoul() 2013-09-11 15:56:56 -07:00
pktcdvd.c block,scsi: fixup blk_get_request dead queue scenarios 2014-08-28 10:03:46 -06:00
ps3disk.c block: Kill bio_segments()/bi_vcnt usage 2013-11-23 22:33:51 -08:00
ps3vram.c block: Convert bio_for_each_segment() to bvec_iter 2013-11-23 22:33:49 -08:00
rbd_types.h rbd: get rid of RBD_MAX_SEG_NAME_LEN 2012-12-17 08:37:29 -06:00
rbd.c rbd: drop parent_ref in rbd_dev_unprobe() unconditionally 2015-01-28 16:12:02 +03:00
skd_main.c block: disable entropy contributions for nonrot devices 2014-10-04 10:55:32 -06:00
skd_s1120.h skd: fix formatting in skd_s1120.h 2013-11-08 09:10:30 -07:00
smart1,2.h fix typos 'comamnd' -> 'command' in comments 2011-02-02 11:31:21 +01:00
sunvdc.c sunvdc: reconnect ldc after vds service domain restarts 2014-12-11 18:52:45 -08:00
swim3.c block: remove struct request buffer member 2014-04-15 14:03:02 -06:00
swim_asm.S m68k: mac - Add SWIM floppy support 2009-03-26 21:15:27 +01:00
swim.c block: drop owner assignment from platform_drivers 2014-10-20 16:20:18 +02:00
sx8.c block,scsi: fixup blk_get_request dead queue scenarios 2014-08-28 10:03:46 -06:00
umem.c block: Convert drivers to immutable biovecs 2013-11-23 22:33:51 -08:00
umem.h
virtio_blk.c block: fix checking return value of blk_mq_init_queue 2015-01-02 10:32:02 -07:00
xen-blkfront.c xen/blkfront: remove redundant flush_op 2014-12-10 12:20:18 -05:00
xsysace.c block: systemace: Remove .owner field for driver 2014-08-21 20:37:54 -05:00
z2ram.c block: remove struct request buffer member 2014-04-15 14:03:02 -06:00