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Merge misc updates from Andrew Morton:
"173 patches.
Subsystems affected by this series: ia64, ocfs2, block, and mm (debug,
pagecache, gup, swap, shmem, memcg, selftests, pagemap, mremap,
bootmem, sparsemem, vmalloc, kasan, pagealloc, memory-failure,
hugetlb, userfaultfd, vmscan, compaction, mempolicy, memblock,
oom-kill, migration, ksm, percpu, vmstat, and madvise)"
* emailed patches from Andrew Morton <[email protected]>: (173 commits)
mm/madvise: add MADV_WILLNEED to process_madvise()
mm/vmstat: remove unneeded return value
mm/vmstat: simplify the array size calculation
mm/vmstat: correct some wrong comments
mm/percpu,c: remove obsolete comments of pcpu_chunk_populated()
selftests: vm: add COW time test for KSM pages
selftests: vm: add KSM merging time test
mm: KSM: fix data type
selftests: vm: add KSM merging across nodes test
selftests: vm: add KSM zero page merging test
selftests: vm: add KSM unmerge test
selftests: vm: add KSM merge test
mm/migrate: correct kernel-doc notation
mm: wire up syscall process_mrelease
mm: introduce process_mrelease system call
memblock: make memblock_find_in_range method private
mm/mempolicy.c: use in_task() in mempolicy_slab_node()
mm/mempolicy: unify the create() func for bind/interleave/prefer-many policies
mm/mempolicy: advertise new MPOL_PREFERRED_MANY
mm/hugetlb: add support for mempolicy MPOL_PREFERRED_MANY
...
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Michael Stapelberg has reported that for workload with short big spikes of
writes (GCC linker seem to trigger this frequently) the write throughput
is heavily underestimated and tends to steadily sink until it reaches
zero. This has rather bad impact on writeback throttling (causing
stalls). The problem is that writeback throughput estimate gets updated
at most once per 200 ms. One update happens early after we submit pages
for writeback (at that point writeout of only small fraction of pages is
completed and thus observed throughput is tiny). Next update happens only
during the next write spike (updates happen only from inode writeback and
dirty throttling code) and if that is more than 1s after previous spike,
we decide system was idle and just ignore whatever was written until this
moment.
Fix the problem by making sure writeback throughput estimate is also
updated shortly after writeback completes to get reasonable estimate of
throughput for spiky workloads.
[[email protected]: avoid division by 0 in wb_update_dirty_ratelimit()]
Link: https://lore.kernel.org/lkml/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Jan Kara <[email protected]>
Reported-by: Michael Stapelberg <[email protected]>
Tested-by: Michael Stapelberg <[email protected]>
Cc: Wu Fengguang <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Patch series "writeback: Fix bandwidth estimates", v4.
Fix estimate of writeback throughput when device is not fully busy doing
writeback. Michael Stapelberg has reported that such workload (e.g.
generated by linking) tends to push estimated throughput down to 0 and as
a result writeback on the device is practically stalled.
The first three patches fix the reported issue, the remaining two patches
are unrelated cleanups of problems I've noticed when reading the code.
This patch (of 4):
Track number of inodes under writeback for each bdi_writeback structure.
We will use this to decide whether wb does any IO and so we can estimate
its writeback throughput. In principle we could use number of pages under
writeback (WB_WRITEBACK counter) for this however normal percpu counter
reads are too inaccurate for our purposes and summing the counter is too
expensive.
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Jan Kara <[email protected]>
Cc: Wu Fengguang <[email protected]>
Cc: Michael Stapelberg <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Don't leak the detaŃ–ls of the timer into the block layer, instead
initialize the timer in bdi_alloc and delete it in bdi_unregister.
Note that this means the timer is initialized (but not armed) for
non-block queues as well now.
Signed-off-by: Christoph Hellwig <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Reviewed-by: Johannes Thumshirn <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>
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Boyang reported that the commit c22d70a162d3 ("writeback, cgroup:
release dying cgwbs by switching attached inodes") causes the kernel to
crash while running xfstests generic/256 on ext4 on aarch64 and ppc64le.
run fstests generic/256 at 2021-07-12 05:41:40
EXT4-fs (vda3): mounted filesystem with ordered data mode. Opts: . Quota mode: none.
Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
Mem abort info:
ESR = 0x96000005
EC = 0x25: DABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
FSC = 0x05: level 1 translation fault
Data abort info:
ISV = 0, ISS = 0x00000005
CM = 0, WnR = 0
user pgtable: 64k pages, 48-bit VAs, pgdp=00000000b0502000
[0000000000000000] pgd=0000000000000000, p4d=0000000000000000, pud=0000000000000000
Internal error: Oops: 96000005 [#1] SMP
Modules linked in: dm_flakey dm_snapshot dm_bufio dm_zero dm_mod loop tls rpcsec_gss_krb5 auth_rpcgss nfsv4 dns_resolver nfs lockd grace fscache netfs rfkill sunrpc ext4 vfat fat mbcache jbd2 drm fuse xfs libcrc32c crct10dif_ce ghash_ce sha2_ce sha256_arm64 sha1_ce virtio_blk virtio_net net_failover virtio_console failover virtio_mmio aes_neon_bs [last unloaded: scsi_debug]
CPU: 0 PID: 408468 Comm: kworker/u8:5 Tainted: G X --------- --- 5.14.0-0.rc1.15.bx.el9.aarch64 #1
Hardware name: QEMU KVM Virtual Machine, BIOS 0.0.0 02/06/2015
Workqueue: events_unbound cleanup_offline_cgwbs_workfn
pstate: 004000c5 (nzcv daIF +PAN -UAO -TCO BTYPE=--)
pc : cleanup_offline_cgwbs_workfn+0x320/0x394
lr : cleanup_offline_cgwbs_workfn+0xe0/0x394
sp : ffff80001554fd10
x29: ffff80001554fd10 x28: 0000000000000000 x27: 0000000000000001
x26: 0000000000000000 x25: 00000000000000e0 x24: ffffd2a2fbe671a8
x23: ffff80001554fd88 x22: ffffd2a2fbe67198 x21: ffffd2a2fc25a730
x20: ffff210412bc3000 x19: ffff210412bc3280 x18: 0000000000000000
x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000
x14: 0000000000000000 x13: 0000000000000030 x12: 0000000000000040
x11: ffff210481572238 x10: ffff21048157223a x9 : ffffd2a2fa276c60
x8 : ffff210484106b60 x7 : 0000000000000000 x6 : 000000000007d18a
x5 : ffff210416a86400 x4 : ffff210412bc0280 x3 : 0000000000000000
x2 : ffff80001554fd88 x1 : ffff210412bc0280 x0 : 0000000000000003
Call trace:
cleanup_offline_cgwbs_workfn+0x320/0x394
process_one_work+0x1f4/0x4b0
worker_thread+0x184/0x540
kthread+0x114/0x120
ret_from_fork+0x10/0x18
Code: d63f0020 97f99963 17ffffa6 f8588263 (f9400061)
---[ end trace e250fe289272792a ]---
Kernel panic - not syncing: Oops: Fatal exception
SMP: stopping secondary CPUs
SMP: failed to stop secondary CPUs 0-2
Kernel Offset: 0x52a2e9fa0000 from 0xffff800010000000
PHYS_OFFSET: 0xfff0defca0000000
CPU features: 0x00200251,23200840
Memory Limit: none
---[ end Kernel panic - not syncing: Oops: Fatal exception ]---
The problem happens when cgwb_release_workfn() races with
cleanup_offline_cgwbs_workfn(): wb_tryget() in
cleanup_offline_cgwbs_workfn() can be called after percpu_ref_exit() is
cgwb_release_workfn(), which is basically a use-after-free error.
Fix the problem by making removing the writeback structure from the
offline list before releasing the percpu reference counter. It will
guarantee that cleanup_offline_cgwbs_workfn() will not see and not
access writeback structures which are about to be released.
Link: https://lkml.kernel.org/r/[email protected]
Fixes: c22d70a162d3 ("writeback, cgroup: release dying cgwbs by switching attached inodes")
Signed-off-by: Roman Gushchin <[email protected]>
Reported-by: Boyang Xue <[email protected]>
Suggested-by: Jan Kara <[email protected]>
Tested-by: Darrick J. Wong <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Dave Chinner <[email protected]>
Cc: Murphy Zhou <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Asynchronously try to release dying cgwbs by switching attached inodes to
the nearest living ancestor wb. It helps to get rid of per-cgroup
writeback structures themselves and of pinned memory and block cgroups,
which are significantly larger structures (mostly due to large per-cpu
statistics data). This prevents memory waste and helps to avoid different
scalability problems caused by large piles of dying cgroups.
Reuse the existing mechanism of inode switching used for foreign inode
detection. To speed things up batch up to 115 inode switching in a single
operation (the maximum number is selected so that the resulting struct
inode_switch_wbs_context can fit into 1024 bytes). Because every
switching consists of two steps divided by an RCU grace period, it would
be too slow without batching. Please note that the whole batch counts as
a single operation (when increasing/decreasing isw_nr_in_flight). This
allows to keep umounting working (flush the switching queue), however
prevents cleanups from consuming the whole switching quota and effectively
blocking the frn switching.
A cgwb cleanup operation can fail due to different reasons (e.g. not
enough memory, the cgwb has an in-flight/pending io, an attached inode in
a wrong state, etc). In this case the next scheduled cleanup will make a
new attempt. An attempt is made each time a new cgwb is offlined (in
other words a memcg and/or a blkcg is deleted by a user). In the future
an additional attempt scheduled by a timer can be implemented.
[[email protected]: replace open-coded "115" with arithmetic]
Link: https://lkml.kernel.org/r/YMEcSBcq/[email protected]
[[email protected]: add smp_mb() to inode_prepare_wbs_switch()]
Link: https://lkml.kernel.org/r/[email protected]
[[email protected]: fix documentation]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Roman Gushchin <[email protected]>
Signed-off-by: Matthew Wilcox (Oracle) <[email protected]>
Acked-by: Tejun Heo <[email protected]>
Acked-by: Dennis Zhou <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Dave Chinner <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Jens Axboe <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Currently there is no way to iterate over inodes attached to a specific
cgwb structure. It limits the ability to efficiently reclaim the
writeback structure itself and associated memory and block cgroup
structures without scanning all inodes belonging to a sb, which can be
prohibitively expensive.
While dirty/in-active-writeback an inode belongs to one of the
bdi_writeback's io lists: b_dirty, b_io, b_more_io and b_dirty_time. Once
cleaned up, it's removed from all io lists. So the inode->i_io_list can
be reused to maintain the list of inodes, attached to a bdi_writeback
structure.
This patch introduces a new wb->b_attached list, which contains all inodes
which were dirty at least once and are attached to the given cgwb. Inodes
attached to the root bdi_writeback structures are never placed on such
list. The following patch will use this list to try to release cgwbs
structures more efficiently.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Roman Gushchin <[email protected]>
Suggested-by: Jan Kara <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Acked-by: Tejun Heo <[email protected]>
Acked-by: Dennis Zhou <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Dave Chinner <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Jens Axboe <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Now that my little helper has landed, use it more. On top of the existing
check this also uses lockdep through the fs_reclaim annotations.
[[email protected]: include linux/sched/mm.h]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Daniel Vetter <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Move the K() macro a little forward to remove the same macro definition.
Link: https://lkml.kernel.org/r/d1ccdf2d3116dce9814f2bcc1f0415ecb4c76ea5.1612862230.git.baolin.wang@linux.alibaba.com
Signed-off-by: Baolin Wang <[email protected]>
Reviewed-by: Andrew Morton <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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The cocci script used in commit bdacbb8d04f ("mm: Use sysfs_emit for
struct kobject * uses") does not convert the name##_show macro because the
macro uses concatenation via ##.
Convert it by hand.
Link: https://lkml.kernel.org/r/45ec6cfc177d743f9c0ebaf35e43969dce43af42.1605376435.git.joe@perches.com
Signed-off-by: Joe Perches <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Pekka Enberg <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Replace the two negative flags that are always used together with a
single positive flag that indicates the writeback capability instead
of two related non-capabilities. Also remove the pointless wrappers
to just check the flag.
Signed-off-by: Christoph Hellwig <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Reviewed-by: Johannes Thumshirn <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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Replace BDI_CAP_NO_ACCT_WB with a positive BDI_CAP_WRITEBACK_ACCT to
make the checks more obvious. Also remove the pointless
bdi_cap_account_writeback wrapper that just obsfucates the check.
Signed-off-by: Christoph Hellwig <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Reviewed-by: Johannes Thumshirn <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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The BDI_CAP_STABLE_WRITES is one of the few bits of information in the
backing_dev_info shared between the block drivers and the writeback code.
To help untangling the dependency replace it with a queue flag and a
superblock flag derived from it. This also helps with the case of e.g.
a file system requiring stable writes due to its own checksumming, but
not forcing it on other users of the block device like the swap code.
One downside is that we an't support the stable_pages_required bdi
attribute in sysfs anymore. It is replaced with a queue attribute which
also is writable for easier testing.
Signed-off-by: Christoph Hellwig <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Reviewed-by: Johannes Thumshirn <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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Set up a readahead size by default, as very few users have a good
reason to change it. This means code, ecryptfs, and orangefs now
set up the values while they were previously missing it, while ubifs,
mtd and vboxsf manually set it to 0 to avoid readahead.
Signed-off-by: Christoph Hellwig <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Acked-by: David Sterba <[email protected]> [btrfs]
Acked-by: Richard Weinberger <[email protected]> [ubifs, mtd]
Signed-off-by: Jens Axboe <[email protected]>
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We never set any congested bits in the group writeback instances of it.
And for the simpler bdi-wide case a simple scalar field is all that
that is needed.
Signed-off-by: Christoph Hellwig <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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Just merge them into their only callers.
Signed-off-by: Christoph Hellwig <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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The name is only printed for a not registered bdi in writeback. Use the
device name there as is more useful anyway for the unlike case that the
warning triggers.
Signed-off-by: Christoph Hellwig <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Reviewed-by: Greg Kroah-Hartman <[email protected]>
Reviewed-by: Bart Van Assche <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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Merge the _node vs normal version and drop the superflous gfp_t argument.
Signed-off-by: Christoph Hellwig <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Reviewed-by: Greg Kroah-Hartman <[email protected]>
Reviewed-by: Bart Van Assche <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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Split out a new bdi_set_owner helper to set the owner, and move the policy
for creating the bdi name back into genhd.c, where it belongs.
Signed-off-by: Christoph Hellwig <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Reviewed-by: Greg Kroah-Hartman <[email protected]>
Reviewed-by: Bart Van Assche <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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bdi_register_va is only used by super.c, which can't be modular.
Signed-off-by: Christoph Hellwig <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Reviewed-by: Greg Kroah-Hartman <[email protected]>
Reviewed-by: Bart Van Assche <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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Cache a copy of the name for the life time of the backing_dev_info
structure so that we can reference it even after unregistering.
Fixes: 68f23b89067f ("memcg: fix a crash in wb_workfn when a device disappears")
Reported-by: Yufen Yu <[email protected]>
Signed-off-by: Christoph Hellwig <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Reviewed-by: Bart Van Assche <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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bdi_dev_name is not a fast path function, move it out of line. This
prepares for using it from modular callers without having to export
an implementation detail like bdi_unknown_name.
Signed-off-by: Christoph Hellwig <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Reviewed-by: Greg Kroah-Hartman <[email protected]>
Reviewed-by: Bart Van Assche <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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blkcg->cgwb_refcnt is used to delay blkcg offlining so that blkgs
don't get offlined while there are active cgwbs on them. However, it
ends up making offlining unordered sometimes causing parents to be
offlined before children.
To fix it, we want child blkcgs to pin the parents' online states
turning the refcnt into a more generic online pinning mechanism.
In prepartion,
* blkcg->cgwb_refcnt -> blkcg->online_pin
* blkcg_cgwb_get/put() -> blkcg_pin/unpin_online()
* Take them out of CONFIG_CGROUP_WRITEBACK
Signed-off-by: Tejun Heo <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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Without memcg, there is a one-to-one mapping between the bdi and
bdi_writeback structures. In this world, things are fairly
straightforward; the first thing bdi_unregister() does is to shutdown
the bdi_writeback structure (or wb), and part of that writeback ensures
that no other work queued against the wb, and that the wb is fully
drained.
With memcg, however, there is a one-to-many relationship between the bdi
and bdi_writeback structures; that is, there are multiple wb objects
which can all point to a single bdi. There is a refcount which prevents
the bdi object from being released (and hence, unregistered). So in
theory, the bdi_unregister() *should* only get called once its refcount
goes to zero (bdi_put will drop the refcount, and when it is zero,
release_bdi gets called, which calls bdi_unregister).
Unfortunately, del_gendisk() in block/gen_hd.c never got the memo about
the Brave New memcg World, and calls bdi_unregister directly. It does
this without informing the file system, or the memcg code, or anything
else. This causes the root wb associated with the bdi to be
unregistered, but none of the memcg-specific wb's are shutdown. So when
one of these wb's are woken up to do delayed work, they try to
dereference their wb->bdi->dev to fetch the device name, but
unfortunately bdi->dev is now NULL, thanks to the bdi_unregister()
called by del_gendisk(). As a result, *boom*.
Fortunately, it looks like the rest of the writeback path is perfectly
happy with bdi->dev and bdi->owner being NULL, so the simplest fix is to
create a bdi_dev_name() function which can handle bdi->dev being NULL.
This also allows us to bulletproof the writeback tracepoints to prevent
them from dereferencing a NULL pointer and crashing the kernel if one is
tracing with memcg's enabled, and an iSCSI device dies or a USB storage
stick is pulled.
The most common way of triggering this will be hotremoval of a device
while writeback with memcg enabled is going on. It was triggering
several times a day in a heavily loaded production environment.
Google Bug Id: 145475544
Link: https://lore.kernel.org/r/[email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Theodore Ts'o <[email protected]>
Cc: Chris Mason <[email protected]>
Cc: Tejun Heo <[email protected]>
Cc: Jens Axboe <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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A removable block device, such as NVMe or SSD connected over Thunderbolt
can be hot-removed any time including when the system is suspended. When
device is hot-removed during suspend and the system gets resumed, kernel
first resumes devices and then thaws the userspace including freezable
workqueues. What happens in that case is that the NVMe driver notices
that the device is unplugged and removes it from the system. This ends
up calling bdi_unregister() for the gendisk which then schedules
wb_workfn() to be run one more time.
However, since the bdi_wq is still frozen flush_delayed_work() call in
wb_shutdown() blocks forever halting system resume process. User sees
this as hang as nothing is happening anymore.
Triggering sysrq-w reveals this:
Workqueue: nvme-wq nvme_remove_dead_ctrl_work [nvme]
Call Trace:
? __schedule+0x2c5/0x630
? wait_for_completion+0xa4/0x120
schedule+0x3e/0xc0
schedule_timeout+0x1c9/0x320
? resched_curr+0x1f/0xd0
? wait_for_completion+0xa4/0x120
wait_for_completion+0xc3/0x120
? wake_up_q+0x60/0x60
__flush_work+0x131/0x1e0
? flush_workqueue_prep_pwqs+0x130/0x130
bdi_unregister+0xb9/0x130
del_gendisk+0x2d2/0x2e0
nvme_ns_remove+0xed/0x110 [nvme_core]
nvme_remove_namespaces+0x96/0xd0 [nvme_core]
nvme_remove+0x5b/0x160 [nvme]
pci_device_remove+0x36/0x90
device_release_driver_internal+0xdf/0x1c0
nvme_remove_dead_ctrl_work+0x14/0x30 [nvme]
process_one_work+0x1c2/0x3f0
worker_thread+0x48/0x3e0
kthread+0x100/0x140
? current_work+0x30/0x30
? kthread_park+0x80/0x80
ret_from_fork+0x35/0x40
This is not limited to NVMes so exactly same issue can be reproduced by
hot-removing SSD (over Thunderbolt) while the system is suspended.
Prevent this from happening by removing WQ_FREEZABLE from bdi_wq.
Reported-by: AceLan Kao <[email protected]>
Link: https://marc.info/?l=linux-kernel&m=138695698516487
Link: https://bugzilla.kernel.org/show_bug.cgi?id=204385
Link: https://lore.kernel.org/lkml/[email protected]/#t
Acked-by: Rafael J. Wysocki <[email protected]>
Signed-off-by: Mika Westerberg <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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Separate out wb_get_lookup() which doesn't try to create one if there
isn't already one from wb_get_create(). This will be used by later
patches.
Reviewed-by: Jan Kara <[email protected]>
Signed-off-by: Tejun Heo <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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There currently is no way to universally identify and lookup a bdi
without holding a reference and pointer to it. This patch adds an
non-recycling bdi->id and implements bdi_get_by_id() which looks up
bdis by their ids. This will be used by memcg foreign inode flushing.
I left bdi_list alone for simplicity and because while rb_tree does
support rcu assignment it doesn't seem to guarantee lossless walk when
walk is racing aginst tree rebalance operations.
Reviewed-by: Jan Kara <[email protected]>
Signed-off-by: Tejun Heo <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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When calling debugfs functions, there is no need to ever check the
return value. The function can work or not, but the code logic should
never do something different based on this.
And as the return value does not matter at all, no need to save the
dentry in struct backing_dev_info, so delete it.
Cc: Andrew Morton <[email protected]>
Cc: Anders Roxell <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: [email protected]
Reviewed-by: Sebastian Andrzej Siewior <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
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Add SPDX license identifiers to all files which:
- Have no license information of any form
- Have EXPORT_.*_SYMBOL_GPL inside which was used in the
initial scan/conversion to ignore the file
These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:
GPL-2.0-only
Signed-off-by: Thomas Gleixner <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
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sync_inodes_sb() can race against cgwb (cgroup writeback) membership
switches and fail to writeback some inodes. For example, if an inode
switches to another wb while sync_inodes_sb() is in progress, the new
wb might not be visible to bdi_split_work_to_wbs() at all or the inode
might jump from a wb which hasn't issued writebacks yet to one which
already has.
This patch adds backing_dev_info->wb_switch_rwsem to synchronize cgwb
switch path against sync_inodes_sb() so that sync_inodes_sb() is
guaranteed to see all the target wbs and inodes can't jump wbs to
escape syncing.
v2: Fixed misplaced rwsem init. Spotted by Jiufei.
Signed-off-by: Tejun Heo <[email protected]>
Reported-by: Jiufei Xue <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Acked-by: Jan Kara <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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Currently, blkcg destruction relies on a sequence of events:
1. Destruction starts. blkcg_css_offline() is called and blkgs
release their reference to the blkcg. This immediately destroys
the cgwbs (writeback).
2. With blkgs giving up their reference, the blkcg ref count should
become zero and eventually call blkcg_css_free() which finally
frees the blkcg.
Jiufei Xue reported that there is a race between blkcg_bio_issue_check()
and cgroup_rmdir(). To remedy this, blkg destruction becomes contingent
on the completion of all writeback associated with the blkcg. A count of
the number of cgwbs is maintained and once that goes to zero, blkg
destruction can follow. This should prevent premature blkg destruction
related to writeback.
The new process for blkcg cleanup is as follows:
1. Destruction starts. blkcg_css_offline() is called which offlines
writeback. Blkg destruction is delayed on the cgwb_refcnt count to
avoid punting potentially large amounts of outstanding writeback
to root while maintaining any ongoing policies. Here, the base
cgwb_refcnt is put back.
2. When the cgwb_refcnt becomes zero, blkcg_destroy_blkgs() is called
and handles destruction of blkgs. This is where the css reference
held by each blkg is released.
3. Once the blkcg ref count goes to zero, blkcg_css_free() is called.
This finally frees the blkg.
It seems in the past blk-throttle didn't do the most understandable
things with taking data from a blkg while associating with current. So,
the simplification and unification of what blk-throttle is doing caused
this.
Fixes: 08e18eab0c579 ("block: add bi_blkg to the bio for cgroups")
Reviewed-by: Josef Bacik <[email protected]>
Signed-off-by: Dennis Zhou <[email protected]>
Cc: Jiufei Xue <[email protected]>
Cc: Joseph Qi <[email protected]>
Cc: Tejun Heo <[email protected]>
Cc: Josef Bacik <[email protected]>
Cc: Jens Axboe <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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The irqsave variant of refcount_dec_and_lock handles irqsave/restore when
taking/releasing the spin lock. With this variant the call of
local_irq_save/restore is no longer required.
[[email protected]: s@atomic_dec_and_lock@refcount_dec_and_lock@g]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Anna-Maria Gleixner <[email protected]>
Signed-off-by: Sebastian Andrzej Siewior <[email protected]>
Acked-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Jens Axboe <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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refcount_t type and corresponding API should be used instead of atomic_t
when the variable is used as a reference counter. This permits avoiding
accidental refcounter overflows that might lead to use-after-free
situations.
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Sebastian Andrzej Siewior <[email protected]>
Reviewed-by: Andrew Morton <[email protected]>
Acked-by: Peter Zijlstra (Intel) <[email protected]>
Suggested-by: Peter Zijlstra <[email protected]>
Cc: Jens Axboe <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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syzbot is reporting NULL pointer dereference at wb_workfn() [1] due to
wb->bdi->dev being NULL. And Dmitry confirmed that wb->state was
WB_shutting_down after wb->bdi->dev became NULL. This indicates that
unregister_bdi() failed to call wb_shutdown() on one of wb objects.
The problem is in cgwb_bdi_unregister() which does cgwb_kill() and thus
drops bdi's reference to wb structures before going through the list of
wbs again and calling wb_shutdown() on each of them. This way the loop
iterating through all wbs can easily miss a wb if that wb has already
passed through cgwb_remove_from_bdi_list() called from wb_shutdown()
from cgwb_release_workfn() and as a result fully shutdown bdi although
wb_workfn() for this wb structure is still running. In fact there are
also other ways cgwb_bdi_unregister() can race with
cgwb_release_workfn() leading e.g. to use-after-free issues:
CPU1 CPU2
cgwb_bdi_unregister()
cgwb_kill(*slot);
cgwb_release()
queue_work(cgwb_release_wq, &wb->release_work);
cgwb_release_workfn()
wb = list_first_entry(&bdi->wb_list, ...)
spin_unlock_irq(&cgwb_lock);
wb_shutdown(wb);
...
kfree_rcu(wb, rcu);
wb_shutdown(wb); -> oops use-after-free
We solve these issues by synchronizing writeback structure shutdown from
cgwb_bdi_unregister() with cgwb_release_workfn() using a new mutex. That
way we also no longer need synchronization using WB_shutting_down as the
mutex provides it for CONFIG_CGROUP_WRITEBACK case and without
CONFIG_CGROUP_WRITEBACK wb_shutdown() can be called only once from
bdi_unregister().
Reported-by: syzbot <[email protected]>
Acked-by: Tejun Heo <[email protected]>
Signed-off-by: Jan Kara <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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mem_cgroup_cgwb_list is a very simple wrapper and it will never be used
outside of code under CONFIG_CGROUP_WRITEBACK. so use memcg->cgwb_list
directly.
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Wang Long <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Acked-by: Tejun Heo <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Reviewed-by: Andrew Morton <[email protected]>
Cc: Johannes Weiner <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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From 0aa2e9b921d6db71150633ff290199554f0842a8 Mon Sep 17 00:00:00 2001
From: Tejun Heo <[email protected]>
Date: Wed, 23 May 2018 10:29:00 -0700
cgwb_release() punts the actual release to cgwb_release_workfn() on
system_wq. Depending on the number of cgroups or block devices, there
can be a lot of cgwb_release_workfn() in flight at the same time.
We're periodically seeing close to 256 kworkers getting stuck with the
following stack trace and overtime the entire system gets stuck.
[<ffffffff810ee40c>] _synchronize_rcu_expedited.constprop.72+0x2fc/0x330
[<ffffffff810ee634>] synchronize_rcu_expedited+0x24/0x30
[<ffffffff811ccf23>] bdi_unregister+0x53/0x290
[<ffffffff811cd1e9>] release_bdi+0x89/0xc0
[<ffffffff811cd645>] wb_exit+0x85/0xa0
[<ffffffff811cdc84>] cgwb_release_workfn+0x54/0xb0
[<ffffffff810a68d0>] process_one_work+0x150/0x410
[<ffffffff810a71fd>] worker_thread+0x6d/0x520
[<ffffffff810ad3dc>] kthread+0x12c/0x160
[<ffffffff81969019>] ret_from_fork+0x29/0x40
[<ffffffffffffffff>] 0xffffffffffffffff
The events leading to the lockup are...
1. A lot of cgwb_release_workfn() is queued at the same time and all
system_wq kworkers are assigned to execute them.
2. They all end up calling synchronize_rcu_expedited(). One of them
wins and tries to perform the expedited synchronization.
3. However, that invovles queueing rcu_exp_work to system_wq and
waiting for it. Because #1 is holding all available kworkers on
system_wq, rcu_exp_work can't be executed. cgwb_release_workfn()
is waiting for synchronize_rcu_expedited() which in turn is waiting
for cgwb_release_workfn() to free up some of the kworkers.
We shouldn't be scheduling hundreds of cgwb_release_workfn() at the
same time. There's nothing to be gained from that. This patch
updates cgwb release path to use a dedicated percpu workqueue with
@max_active of 1.
While this resolves the problem at hand, it might be a good idea to
isolate rcu_exp_work to its own workqueue too as it can be used from
various paths and is prone to this sort of indirect A-A deadlocks.
Signed-off-by: Tejun Heo <[email protected]>
Cc: "Paul E. McKenney" <[email protected]>
Cc: [email protected]
Signed-off-by: Jens Axboe <[email protected]>
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syzbot is reporting use after free bug in debugfs_remove() [1].
This is because fault injection made memory allocation for
debugfs_create_file() from bdi_debug_register() from bdi_register_va()
fail and continued with setting WB_registered. But when debugfs_remove()
is called from debugfs_remove(bdi->debug_dir) from bdi_debug_unregister()
from bdi_unregister() from release_bdi() because WB_registered was set
by bdi_register_va(), IS_ERR_OR_NULL(bdi->debug_dir) == false despite
debugfs_remove(bdi->debug_dir) was already called from bdi_register_va().
Fix this by making IS_ERR_OR_NULL(bdi->debug_dir) == true.
[1] https://syzkaller.appspot.com/bug?id=5ab4efd91a96dcea9b68104f159adf4af2a6dfc1
Signed-off-by: Tetsuo Handa <[email protected]>
Reported-by: syzbot <[email protected]>
Fixes: 97f07697932e6faf ("bdi: convert bdi_debug_register to int")
Cc: weiping zhang <[email protected]>
Reviewed-by: Greg Kroah-Hartman <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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syzbot is reporting hung tasks at wait_on_bit(WB_shutting_down) in
wb_shutdown() [1]. This seems to be because commit 5318ce7d46866e1d ("bdi:
Shutdown writeback on all cgwbs in cgwb_bdi_destroy()") forgot to call
wake_up_bit(WB_shutting_down) after clear_bit(WB_shutting_down).
Introduce a helper function clear_and_wake_up_bit() and use it, in order
to avoid similar errors in future.
[1] https://syzkaller.appspot.com/bug?id=b297474817af98d5796bc544e1bb806fc3da0e5e
Signed-off-by: Tetsuo Handa <[email protected]>
Reported-by: syzbot <[email protected]>
Fixes: 5318ce7d46866e1d ("bdi: Shutdown writeback on all cgwbs in cgwb_bdi_destroy()")
Cc: Tejun Heo <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
Suggested-by: Linus Torvalds <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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memcg reclaim may alter pgdat->flags based on the state of LRU lists in
cgroup and its children. PGDAT_WRITEBACK may force kswapd to sleep
congested_wait(), PGDAT_DIRTY may force kswapd to writeback filesystem
pages. But the worst here is PGDAT_CONGESTED, since it may force all
direct reclaims to stall in wait_iff_congested(). Note that only kswapd
have powers to clear any of these bits. This might just never happen if
cgroup limits configured that way. So all direct reclaims will stall as
long as we have some congested bdi in the system.
Leave all pgdat->flags manipulations to kswapd. kswapd scans the whole
pgdat, only kswapd can clear pgdat->flags once node is balanced, thus
it's reasonable to leave all decisions about node state to kswapd.
Why only kswapd? Why not allow to global direct reclaim change these
flags? It is because currently only kswapd can clear these flags. I'm
less worried about the case when PGDAT_CONGESTED falsely not set, and
more worried about the case when it falsely set. If direct reclaimer
sets PGDAT_CONGESTED, do we have guarantee that after the congestion
problem is sorted out, kswapd will be woken up and clear the flag? It
seems like there is no such guarantee. E.g. direct reclaimers may
eventually balance pgdat and kswapd simply won't wake up (see
wakeup_kswapd()).
Moving pgdat->flags manipulation to kswapd, means that cgroup2 recalim
now loses its congestion throttling mechanism. Add per-cgroup
congestion state and throttle cgroup2 reclaimers if memcg is in
congestion state.
Currently there is no need in per-cgroup PGDAT_WRITEBACK and PGDAT_DIRTY
bits since they alter only kswapd behavior.
The problem could be easily demonstrated by creating heavy congestion in
one cgroup:
echo "+memory" > /sys/fs/cgroup/cgroup.subtree_control
mkdir -p /sys/fs/cgroup/congester
echo 512M > /sys/fs/cgroup/congester/memory.max
echo $$ > /sys/fs/cgroup/congester/cgroup.procs
/* generate a lot of diry data on slow HDD */
while true; do dd if=/dev/zero of=/mnt/sdb/zeroes bs=1M count=1024; done &
....
while true; do dd if=/dev/zero of=/mnt/sdb/zeroes bs=1M count=1024; done &
and some job in another cgroup:
mkdir /sys/fs/cgroup/victim
echo 128M > /sys/fs/cgroup/victim/memory.max
# time cat /dev/sda > /dev/null
real 10m15.054s
user 0m0.487s
sys 1m8.505s
According to the tracepoint in wait_iff_congested(), the 'cat' spent 50%
of the time sleeping there.
With the patch, cat don't waste time anymore:
# time cat /dev/sda > /dev/null
real 5m32.911s
user 0m0.411s
sys 0m56.664s
[[email protected]: congestion state should be per-node]
Link: http://lkml.kernel.org/r/[email protected]
[[email protected]: make congestion state per-cgroup-per-node instead of just per-cgroup[
Link: http://lkml.kernel.org/r/[email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Andrey Ryabinin <[email protected]>
Reviewed-by: Shakeel Butt <[email protected]>
Acked-by: Johannes Weiner <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Tejun Heo <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Steven Rostedt <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Merge updates from Andrew Morton:
- a few misc things
- ocfs2 updates
- the v9fs maintainers have been missing for a long time. I've taken
over v9fs patch slinging.
- most of MM
* emailed patches from Andrew Morton <[email protected]>: (116 commits)
mm,oom_reaper: check for MMF_OOM_SKIP before complaining
mm/ksm: fix interaction with THP
mm/memblock.c: cast constant ULLONG_MAX to phys_addr_t
headers: untangle kmemleak.h from mm.h
include/linux/mmdebug.h: make VM_WARN* non-rvals
mm/page_isolation.c: make start_isolate_page_range() fail if already isolated
mm: change return type to vm_fault_t
mm, oom: remove 3% bonus for CAP_SYS_ADMIN processes
mm, page_alloc: wakeup kcompactd even if kswapd cannot free more memory
kernel/fork.c: detect early free of a live mm
mm: make counting of list_lru_one::nr_items lockless
mm/swap_state.c: make bool enable_vma_readahead and swap_vma_readahead() static
block_invalidatepage(): only release page if the full page was invalidated
mm: kernel-doc: add missing parameter descriptions
mm/swap.c: remove @cold parameter description for release_pages()
mm/nommu: remove description of alloc_vm_area
zram: drop max_zpage_size and use zs_huge_class_size()
zsmalloc: introduce zs_huge_class_size()
mm: fix races between swapoff and flush dcache
fs/direct-io.c: minor cleanups in do_blockdev_direct_IO
...
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...instead of open coding file operations followed by custom ->open()
callbacks per each attribute.
[[email protected]: add tags, fix compilation issue]
Link: http://lkml.kernel.org/r/[email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Andy Shevchenko <[email protected]>
Reviewed-by: Matthew Wilcox <[email protected]>
Reviewed-by: Andrew Morton <[email protected]>
Reviewed-by: Sergey Senozhatsky <[email protected]>
Acked-by: Christoph Lameter <[email protected]>
Cc: Tejun Heo <[email protected]>
Cc: Dennis Zhou <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: Nitin Gupta <[email protected]>
Cc: Sergey Senozhatsky <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Signed-off-by: Jiufei Xue <[email protected]>
Acked-by: Tejun Heo <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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This reverts commit a0747a859ef6d3cc5b6cd50eb694499b78dd0025.
It breaks some booting for some users, and more than a week
into this, there's still no good fix. Revert this commit
for now until a solution has been found.
Reported-by: Laura Abbott <[email protected]>
Reported-by: Bruno Wolff III <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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In order to make error handle more cleaner we call bdi_debug_register
before set state to WB_registered, that we can avoid call bdi_unregister
in release_bdi().
Reviewed-by: Jan Kara <[email protected]>
Signed-off-by: weiping zhang <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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Convert bdi_debug_register to int and then do error handle for it.
Reviewed-by: Jan Kara <[email protected]>
Signed-off-by: weiping zhang <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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After commit b35bd0d9f8a8, pdflush_proc_obsolete() is no longer
used. Kill the function and declaration.
Reported-by: Rakesh Pandit <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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If the 'kmalloc' fails, we must go through the existing error handling
path.
Signed-off-by: Christophe JAILLET <[email protected]>
Fixes: 52ebea749aae ("writeback: make backing_dev_info host cgroup-specific bdi_writebacks")
Reviewed-by: Jan Kara <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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Drop 'parent' argument of bdi_register() and bdi_register_va(). It is
always NULL.
Reviewed-by: Christoph Hellwig <[email protected]>
Signed-off-by: Jan Kara <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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Now that all backing_dev_info structure are allocated separately, we can
drop some unused functions.
Reviewed-by: Christoph Hellwig <[email protected]>
Signed-off-by: Jan Kara <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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MTD will want to call bdi_alloc_node() and bdi_put() directly. Export
these functions.
Reviewed-by: Christoph Hellwig <[email protected]>
Signed-off-by: Jan Kara <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
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