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>
Pull block fixes from Jens Axboe:
"Bigger than usual at this time, mostly due to the O_DIRECT corruption
issue and the fact that I was on vacation last week. This contains:
- NVMe pull request with two fixes for the FC code, and two target
fixes (Christoph)
- a DIF bio reset iteration fix (Greg Edwards)
- two nbd reply and requeue fixes (Josef)
- SCSI timeout fixup (Keith)
- a small series that fixes an issue with bio_iov_iter_get_pages(),
which ended up causing corruption for larger sized O_DIRECT writes
that ended up racing with buffered writes (Martin Wilck)"
* tag 'for-linus-20180727' of git://git.kernel.dk/linux-block:
block: reset bi_iter.bi_done after splitting bio
block: bio_iov_iter_get_pages: pin more pages for multi-segment IOs
blkdev: __blkdev_direct_IO_simple: fix leak in error case
block: bio_iov_iter_get_pages: fix size of last iovec
nvmet: only check for filebacking on -ENOTBLK
nvmet: fixup crash on NULL device path
scsi: set timed out out mq requests to complete
blk-mq: export setting request completion state
nvme: if_ready checks to fail io to deleting controller
nvmet-fc: fix target sgl list on large transfers
nbd: handle unexpected replies better
nbd: don't requeue the same request twice.
If the server or network is misbehaving and we get an unexpected reply we can sometimes miss the request not being started and wait on a request and never get a response, or even double complete the same request. Fix this by replacing the send_complete completion with just a per command lock. Add a per command cookie as well so that we can know if we're getting a double completion for a previous event. Also check to make sure we dont have REQUEUED set as that means we raced with the timeout handler and need to just let the retry occur. Signed-off-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
We can race with the snd timeout and the per-request timeout and end up requeuing the same request twice. We can't use the send_complete completion to tell if everything is ok because we hold the tx_lock during send, so the timeout stuff will block waiting to mark the socket dead, and we could be marked complete and still requeue. Instead add a flag to the socket so we know whether we've been requeued yet. Signed-off-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pull block fixes from Jens Axboe: "Two minor fixes for this series: - add LOOP_SET_BLOCK_SIZE as compat ioctl (Evan Green) - drbd use-after-free fix (Lars Ellenberg)" * tag 'for-linus-20180706' of git://git.kernel.dk/linux-block: loop: Add LOOP_SET_BLOCK_SIZE in compat ioctl drbd: fix access after free
This change adds LOOP_SET_BLOCK_SIZE as one of the supported ioctls in lo_compat_ioctl. It only takes an unsigned long argument, and in practice a 32-bit value works fine. Reviewed-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Evan Green <evgreen@chromium.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
We have
struct drbd_requests { ... struct bio *private_bio; ... }
to hold a bio clone for local submission.
On local IO completion, we put that bio, and in case we want to use the
result later, we overload that member to hold the ERR_PTR() of the
completion result,
Which, before v4.3, used to be the passed in "int error",
so we could first bio_put(), then assign.
v4.3-rc1~100^2~21 4246a0b63bd8 block: add a bi_error field to struct bio
changed that:
bio_put(req->private_bio);
- req->private_bio = ERR_PTR(error);
+ req->private_bio = ERR_PTR(bio->bi_error);
Which introduces an access after free,
because it was non obvious that req->private_bio == bio.
Impact of that was mostly unnoticable, because we only use that value
in a multiple-failure case, and even then map any "unexpected" error
code to EIO, so worst case we could potentially mask a more specific
error with EIO in a multiple failure case.
Unless the pointed to memory region was unmapped, as is the case with
CONFIG_DEBUG_PAGEALLOC, in which case this results in
BUG: unable to handle kernel paging request
v4.13-rc1~70^2~75 4e4cbee93d56 block: switch bios to blk_status_t
changes it further to
bio_put(req->private_bio);
req->private_bio = ERR_PTR(blk_status_to_errno(bio->bi_status));
And blk_status_to_errno() now contains a WARN_ON_ONCE() for unexpected
values, which catches this "sometimes", if the memory has been reused
quickly enough for other things.
Should also go into stable since 4.3, with the trivial change around 4.13.
Cc: stable@vger.kernel.org
Fixes: 4246a0b63bd8 block: add a bi_error field to struct bio
Reported-by: Sarah Newman <srn@prgmr.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pull block fixes from Jens Axboe: "Small set of fixes for this series. Mostly just minor fixes, the only oddball in here is the sg change. The sg change came out of the stall fix for NVMe, where we added a mempool and limited us to a single page allocation. CONFIG_SG_DEBUG sort-of ruins that, since we'd need to account for that. That's actually a generic problem, since lots of drivers need to allocate SG lists. So this just removes support for CONFIG_SG_DEBUG, which I added back in 2007 and to my knowledge it was never useful. Anyway, outside of that, this pull contains: - clone of request with special payload fix (Bart) - drbd discard handling fix (Bart) - SATA blk-mq stall fix (me) - chunk size fix (Keith) - double free nvme rdma fix (Sagi)" * tag 'for-linus-20180629' of git://git.kernel.dk/linux-block: sg: remove ->sg_magic member drbd: Fix drbd_request_prepare() discard handling blk-mq: don't queue more if we get a busy return block: Fix cloning of requests with a special payload nvme-rdma: fix possible double free of controller async event buffer block: Fix transfer when chunk sectors exceeds max
Fix the test that verifies whether bio_op(bio) represents a discard
or write zeroes operation. Compile-tested only.
Cc: Philipp Reisner <philipp.reisner@linbit.com>
Cc: Lars Ellenberg <lars.ellenberg@linbit.com>
Fixes: 7435e9018f91 ("drbd: zero-out partial unaligned discards on local backend")
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pull block fixes from Jens Axboe: - Further timeout fixes. We aren't quite there yet, so expect another round of fixes for that to completely close some of the IRQ vs completion races. (Christoph/Bart) - Set of NVMe fixes from the usual suspects, mostly error handling - Two off-by-one fixes (Dan) - Another bdi race fix (Jan) - Fix nbd reconfigure with NBD_DISCONNECT_ON_CLOSE (Doron) * tag 'for-linus-20180623' of git://git.kernel.dk/linux-block: blk-mq: Fix timeout handling in case the timeout handler returns BLK_EH_DONE bdi: Fix another oops in wb_workfn() lightnvm: Remove depends on HAS_DMA in case of platform dependency nvme-pci: limit max IO size and segments to avoid high order allocations nvme-pci: move nvme_kill_queues to nvme_remove_dead_ctrl nvme-fc: release io queues to allow fast fail nbd: Add the nbd NBD_DISCONNECT_ON_CLOSE config flag. block: sed-opal: Fix a couple off by one bugs blk-mq-debugfs: Off by one in blk_mq_rq_state_name() nvmet: reset keep alive timer in controller enable nvme-rdma: don't override opts->queue_size nvme-rdma: Fix command completion race at error recovery nvme-rdma: fix possible free of a non-allocated async event buffer nvme-rdma: fix possible double free condition when failing to create a controller Revert "block: Add warning for bi_next not NULL in bio_endio()" block: fix timeout changes for legacy request drivers