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4f7a7beaee
linux/drivers/block
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Minchan Kim 4f7a7beaee zram: remove BD_CAP_SYNCHRONOUS_IO with writeback feature 
If zram supports writeback feature, it's no longer a
BD_CAP_SYNCHRONOUS_IO device beause zram does asynchronous IO operations
for incompressible pages.

Do not pretend to be synchronous IO device.  It makes the system very
sluggish due to waiting for IO completion from upper layers.

Furthermore, it causes a user-after-free problem because swap thinks the
opearion is done when the IO functions returns so it can free the page
(e.g., lock_page_or_retry and goto out_release in do_swap_page) but in
fact, IO is asynchronous so the driver could access a just freed page
afterward.

This patch fixes the problem.

  BUG: Bad page state in process qemu-system-x86  pfn:3dfab21
  page:ffffdfb137eac840 count:0 mapcount:0 mapping:0000000000000000 index:0x1
  flags: 0x17fffc000000008(uptodate)
  raw: 017fffc000000008 dead000000000100 dead000000000200 0000000000000000
  raw: 0000000000000001 0000000000000000 00000000ffffffff 0000000000000000
  page dumped because: PAGE_FLAGS_CHECK_AT_PREP flag set
  bad because of flags: 0x8(uptodate)
  CPU: 4 PID: 1039 Comm: qemu-system-x86 Tainted: G    B 4.18.0-rc5+ #1
  Hardware name: Supermicro Super Server/X10SRL-F, BIOS 2.0b 05/02/2017
  Call Trace:
    dump_stack+0x5c/0x7b
    bad_page+0xba/0x120
    get_page_from_freelist+0x1016/0x1250
    __alloc_pages_nodemask+0xfa/0x250
    alloc_pages_vma+0x7c/0x1c0
    do_swap_page+0x347/0x920
    __handle_mm_fault+0x7b4/0x1110
    handle_mm_fault+0xfc/0x1f0
    __get_user_pages+0x12f/0x690
    get_user_pages_unlocked+0x148/0x1f0
    __gfn_to_pfn_memslot+0xff/0x3c0 [kvm]
    try_async_pf+0x87/0x230 [kvm]
    tdp_page_fault+0x132/0x290 [kvm]
    kvm_mmu_page_fault+0x74/0x570 [kvm]
    kvm_arch_vcpu_ioctl_run+0x9b3/0x1990 [kvm]
    kvm_vcpu_ioctl+0x388/0x5d0 [kvm]
    do_vfs_ioctl+0xa2/0x630
    ksys_ioctl+0x70/0x80
    __x64_sys_ioctl+0x16/0x20
    do_syscall_64+0x55/0x100
    entry_SYSCALL_64_after_hwframe+0x44/0xa9

Link: https://lore.kernel.org/lkml/0516ae2d-b0fd-92c5-aa92-112ba7bd32fc@contabo.de/
Link: http://lkml.kernel.org/r/20180802051112.86174-1-minchan@kernel.org
[minchan@kernel.org: fix changelog, add comment]
 Link: https://lore.kernel.org/lkml/0516ae2d-b0fd-92c5-aa92-112ba7bd32fc@contabo.de/
 Link: http://lkml.kernel.org/r/20180802051112.86174-1-minchan@kernel.org
 Link: http://lkml.kernel.org/r/20180805233722.217347-1-minchan@kernel.org
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Minchan Kim <minchan@kernel.org>
Reported-by: Tino Lehnig <tino.lehnig@contabo.de>
Tested-by: Tino Lehnig <tino.lehnig@contabo.de>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>	[4.15+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-08-10 20:19:59 -07:00
..
aoe block drivers/block: Use octal not symbolic permissions 2018-05-24 13:38:59 -06:00
drbd for-linus-20180706 2018-07-06 19:13:42 -07:00
mtip32xx blk-mq: only iterate over inflight requests in blk_mq_tagset_busy_iter 2018-05-30 11:31:34 -06:00
paride block: sanitize blk_get_request calling conventions 2018-05-14 08:55:12 -06:00
rsxx treewide: kzalloc() -> kcalloc() 2018-06-12 16:19:22 -07:00
xen-blkback treewide: kzalloc() -> kcalloc() 2018-06-12 16:19:22 -07:00
zram zram: remove BD_CAP_SYNCHRONOUS_IO with writeback feature 2018-08-10 20:19:59 -07:00
amiflop.c genhd: Rename get_disk() to get_disk_and_module() 2018-02-26 09:48:42 -07:00
ataflop.c genhd: Rename get_disk() to get_disk_and_module() 2018-02-26 09:48:42 -07:00
brd.c block drivers/block: Use octal not symbolic permissions 2018-05-24 13:38:59 -06:00
cryptoloop.c block: cryptoloop - Fix build warning 2017-09-26 07:41:22 -06:00
DAC960.c treewide: kmalloc() -> kmalloc_array() 2018-06-12 16:19:22 -07:00
DAC960.h DAC960: don't use block layer bounce buffers 2018-05-11 15:07:54 -06:00
floppy.c block drivers/block: Use octal not symbolic permissions 2018-05-24 13:38:59 -06:00
Kconfig null_blk: remove explicit 'select FAULT_INJECTION' 2018-01-11 07:58:31 -07:00
loop.c for-linus-20180706 2018-07-06 19:13:42 -07:00
loop.h loop: remember whether sysfs_create_group() was done 2018-05-07 15:26:36 -06:00
Makefile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
nbd.c nbd: handle unexpected replies better 2018-07-16 10:14:40 -06:00
null_blk.c for-linus-20180623 2018-06-24 06:33:54 +08:00
pktcdvd.c Merge branch 'hch.procfs' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-06-04 10:00:01 -07:00
ps3disk.c ps3disk: handle highmem pages 2018-05-11 15:08:03 -06:00
ps3vram.c treewide: kzalloc() -> kcalloc() 2018-06-12 16:19:22 -07:00
rbd_types.h rbd: RBD_V{1,2}_DATA_FORMAT macros 2017-02-20 12:16:15 +01:00
rbd.c The main piece is a set of libceph changes that revamps how OSD 2018-06-15 07:24:58 +09:00
skd_main.c block: Use blk_queue_flag_*() in drivers instead of queue_flag_*() 2018-03-08 14:13:48 -07:00
skd_s1120.h skd: Use __packed only when needed 2017-08-18 08:45:29 -06:00
sunvdc.c treewide: setup_timer() -> timer_setup() 2017-11-21 15:57:07 -08:00
swim3.c block/swim: Rename macros to avoid inconsistent inverted logic 2018-04-16 21:49:35 -06:00
swim_asm.S
swim.c block/swim: Select appropriate drive on device open 2018-04-16 21:49:35 -06:00
sx8.c block: sanitize blk_get_request calling conventions 2018-05-14 08:55:12 -06:00
umem.c block: Fix a race between the cgroup code and request queue initialization 2018-02-28 12:23:35 -07:00
umem.h
virtio_blk.c block drivers/block: Use octal not symbolic permissions 2018-05-24 13:38:59 -06:00
xen-blkfront.c treewide: kzalloc() -> kcalloc() 2018-06-12 16:19:22 -07:00
xsysace.c treewide: setup_timer() -> timer_setup() 2017-11-21 15:57:07 -08:00
z2ram.c treewide: kmalloc() -> kmalloc_array() 2018-06-12 16:19:22 -07:00