05 Aug, 2016
1 commit
-
The name for a bdi of a gendisk is derived from the gendisk's devt.
However, since the gendisk is destroyed before the bdi it leaves a
window where a new gendisk could dynamically reuse the same devt while a
bdi with the same name is still live. Arrange for the bdi to hold a
reference against its "owner" disk device while it is registered.
Otherwise we can hit sysfs duplicate name collisions like the following:WARNING: CPU: 10 PID: 2078 at fs/sysfs/dir.c:31 sysfs_warn_dup+0x64/0x80
sysfs: cannot create duplicate filename '/devices/virtual/bdi/259:1'Hardware name: HP ProLiant DL580 Gen8, BIOS P79 05/06/2015
0000000000000286 0000000002c04ad5 ffff88006f24f970 ffffffff8134caec
ffff88006f24f9c0 0000000000000000 ffff88006f24f9b0 ffffffff8108c351
0000001f0000000c ffff88105d236000 ffff88105d1031e0 ffff8800357427f8
Call Trace:
[] dump_stack+0x63/0x87
[] __warn+0xd1/0xf0
[] warn_slowpath_fmt+0x5f/0x80
[] sysfs_warn_dup+0x64/0x80
[] sysfs_create_dir_ns+0x7e/0x90
[] kobject_add_internal+0xaa/0x320
[] ? vsnprintf+0x34e/0x4d0
[] kobject_add+0x75/0xd0
[] ? mutex_lock+0x12/0x2f
[] device_add+0x125/0x610
[] device_create_groups_vargs+0xd8/0x100
[] device_create_vargs+0x1c/0x20
[] bdi_register+0x8c/0x180
[] bdi_register_dev+0x27/0x30
[] add_disk+0x175/0x4a0Cc:
Reported-by: Yi Zhang
Tested-by: Yi Zhang
Signed-off-by: Dan WilliamsFixed up missing 0 return in bdi_register_owner().
Signed-off-by: Jens Axboe
29 Jul, 2016
1 commit
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This moves the LRU lists from the zone to the node and related data such
as counters, tracing, congestion tracking and writeback tracking.Unfortunately, due to reclaim and compaction retry logic, it is
necessary to account for the number of LRU pages on both zone and node
logic. Most reclaim logic is based on the node counters but the retry
logic uses the zone counters which do not distinguish inactive and
active sizes. It would be possible to leave the LRU counters on a
per-zone basis but it's a heavier calculation across multiple cache
lines that is much more frequent than the retry checks.Other than the LRU counters, this is mostly a mechanical patch but note
that it introduces a number of anomalies. For example, the scans are
per-zone but using per-node counters. We also mark a node as congested
when a zone is congested. This causes weird problems that are fixed
later but is easier to review.In the event that there is excessive overhead on 32-bit systems due to
the nodes being on LRU then there are two potential solutions1. Long-term isolation of highmem pages when reclaim is lowmem
When pages are skipped, they are immediately added back onto the LRU
list. If lowmem reclaim persisted for long periods of time, the same
highmem pages get continually scanned. The idea would be that lowmem
keeps those pages on a separate list until a reclaim for highmem pages
arrives that splices the highmem pages back onto the LRU. It potentially
could be implemented similar to the UNEVICTABLE list.That would reduce the skip rate with the potential corner case is that
highmem pages have to be scanned and reclaimed to free lowmem slab pages.2. Linear scan lowmem pages if the initial LRU shrink fails
This will break LRU ordering but may be preferable and faster during
memory pressure than skipping LRU pages.Link: http://lkml.kernel.org/r/1467970510-21195-4-git-send-email-mgorman@techsingularity.net
Signed-off-by: Mel Gorman
Acked-by: Johannes Weiner
Acked-by: Vlastimil Babka
Cc: Hillf Danton
Cc: Joonsoo Kim
Cc: Michal Hocko
Cc: Minchan Kim
Cc: Rik van Riel
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
21 May, 2016
1 commit
-
wait_iff_congested has been used to throttle allocator before it retried
another round of direct reclaim to allow the writeback to make some
progress and prevent reclaim from looping over dirty/writeback pages
without making any progress.We used to do congestion_wait before commit 0e093d99763e ("writeback: do
not sleep on the congestion queue if there are no congested BDIs or if
significant congestion is not being encountered in the current zone")
but that led to undesirable stalls and sleeping for the full timeout
even when the BDI wasn't congested. Hence wait_iff_congested was used
instead.But it seems that even wait_iff_congested doesn't work as expected. We
might have a small file LRU list with all pages dirty/writeback and yet
the bdi is not congested so this is just a cond_resched in the end and
can end up triggering pre mature OOM.This patch replaces the unconditional wait_iff_congested by
congestion_wait which is executed only if we _know_ that the last round
of direct reclaim didn't make any progress and dirty+writeback pages are
more than a half of the reclaimable pages on the zone which might be
usable for our target allocation. This shouldn't reintroduce stalls
fixed by 0e093d99763e because congestion_wait is called only when we are
getting hopeless when sleeping is a better choice than OOM with many
pages under IO.We have to preserve logic introduced by commit 373ccbe59270 ("mm,
vmstat: allow WQ concurrency to discover memory reclaim doesn't make any
progress") into the __alloc_pages_slowpath now that wait_iff_congested
is not used anymore. As the only remaining user of wait_iff_congested
is shrink_inactive_list we can remove the WQ specific short sleep from
wait_iff_congested because the sleep is needed to be done only once in
the allocation retry cycle.[mhocko@suse.com: high_zoneidx->ac_classzone_idx to evaluate memory reserves properly]
Link: http://lkml.kernel.org/r/1463051677-29418-2-git-send-email-mhocko@kernel.org
Signed-off-by: Michal Hocko
Acked-by: Hillf Danton
Cc: David Rientjes
Cc: Johannes Weiner
Cc: Joonsoo Kim
Cc: Mel Gorman
Cc: Tetsuo Handa
Cc: Vladimir Davydov
Cc: Vlastimil Babka
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
01 Apr, 2016
1 commit
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The right variable definition should be wb_congested_state that
include WB_async_congested and WB_sync_congested. So fix it.Signed-off-by: Kaixu Xia
Acked-by: Tejun Heo
Signed-off-by: Jens Axboe
18 Mar, 2016
1 commit
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Most of the mm subsystem uses pr_ so make it consistent.
Miscellanea:
- Realign arguments
- Add missing newline to format
- kmemleak-test.c has a "kmemleak: " prefix added to the
"Kmemleak testing" logging message via pr_fmtSigned-off-by: Joe Perches
Acked-by: Tejun Heo [percpu]
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
12 Feb, 2016
1 commit
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We need to use post-decrement to get percpu_counter_destroy() called on
&wb->stat[0]. Moreover, the pre-decremebt would cause infinite
out-of-bounds accesses if the setup code failed at i==0.Signed-off-by: Rasmus Villemoes
Cc: Johannes Weiner
Cc: Michal Hocko
Cc: Vladimir Davydov
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
06 Feb, 2016
1 commit
-
Jan Stancek has reported that system occasionally hanging after "oom01"
testcase from LTP triggers OOM. Guessing from a result that there is a
kworker thread doing memory allocation and the values between "Node 0
Normal free:" and "Node 0 Normal:" differs when hanging, vmstat is not
up-to-date for some reason.According to commit 373ccbe59270 ("mm, vmstat: allow WQ concurrency to
discover memory reclaim doesn't make any progress"), it meant to force
the kworker thread to take a short sleep, but it by error used
schedule_timeout(1). We missed that schedule_timeout() in state
TASK_RUNNING doesn't do anything.Fix it by using schedule_timeout_uninterruptible(1) which forces the
kworker thread to take a short sleep in order to make sure that vmstat
is up-to-date.Fixes: 373ccbe59270 ("mm, vmstat: allow WQ concurrency to discover memory reclaim doesn't make any progress")
Signed-off-by: Tetsuo Handa
Reported-by: Jan Stancek
Acked-by: Michal Hocko
Cc: Tejun Heo
Cc: Cristopher Lameter
Cc: Joonsoo Kim
Cc: Arkadiusz Miskiewicz
Cc:
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
15 Jan, 2016
1 commit
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A later patch will need this symbol in files other than memcontrol.c, so
export it now and replace mem_cgroup_root_css at the same time.Signed-off-by: Johannes Weiner
Acked-by: Michal Hocko
Acked-by: David S. Miller
Reviewed-by: Vladimir Davydov
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
13 Dec, 2015
1 commit
-
Tetsuo Handa has reported that the system might basically livelock in
OOM condition without triggering the OOM killer.The issue is caused by internal dependency of the direct reclaim on
vmstat counter updates (via zone_reclaimable) which are performed from
the workqueue context. If all the current workers get assigned to an
allocation request, though, they will be looping inside the allocator
trying to reclaim memory but zone_reclaimable can see stalled numbers so
it will consider a zone reclaimable even though it has been scanned way
too much. WQ concurrency logic will not consider this situation as a
congested workqueue because it relies that worker would have to sleep in
such a situation. This also means that it doesn't try to spawn new
workers or invoke the rescuer thread if the one is assigned to the
queue.In order to fix this issue we need to do two things. First we have to
let wq concurrency code know that we are in trouble so we have to do a
short sleep. In order to prevent from issues handled by 0e093d99763e
("writeback: do not sleep on the congestion queue if there are no
congested BDIs or if significant congestion is not being encountered in
the current zone") we limit the sleep only to worker threads which are
the ones of the interest anyway.The second thing to do is to create a dedicated workqueue for vmstat and
mark it WQ_MEM_RECLAIM to note it participates in the reclaim and to
have a spare worker thread for it.Signed-off-by: Michal Hocko
Reported-by: Tetsuo Handa
Cc: Tejun Heo
Cc: Cristopher Lameter
Cc: Joonsoo Kim
Cc: Arkadiusz Miskiewicz
Cc:
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
07 Nov, 2015
1 commit
-
…d avoiding waking kswapd
__GFP_WAIT has been used to identify atomic context in callers that hold
spinlocks or are in interrupts. They are expected to be high priority and
have access one of two watermarks lower than "min" which can be referred
to as the "atomic reserve". __GFP_HIGH users get access to the first
lower watermark and can be called the "high priority reserve".Over time, callers had a requirement to not block when fallback options
were available. Some have abused __GFP_WAIT leading to a situation where
an optimisitic allocation with a fallback option can access atomic
reserves.This patch uses __GFP_ATOMIC to identify callers that are truely atomic,
cannot sleep and have no alternative. High priority users continue to use
__GFP_HIGH. __GFP_DIRECT_RECLAIM identifies callers that can sleep and
are willing to enter direct reclaim. __GFP_KSWAPD_RECLAIM to identify
callers that want to wake kswapd for background reclaim. __GFP_WAIT is
redefined as a caller that is willing to enter direct reclaim and wake
kswapd for background reclaim.This patch then converts a number of sites
o __GFP_ATOMIC is used by callers that are high priority and have memory
pools for those requests. GFP_ATOMIC uses this flag.o Callers that have a limited mempool to guarantee forward progress clear
__GFP_DIRECT_RECLAIM but keep __GFP_KSWAPD_RECLAIM. bio allocations fall
into this category where kswapd will still be woken but atomic reserves
are not used as there is a one-entry mempool to guarantee progress.o Callers that are checking if they are non-blocking should use the
helper gfpflags_allow_blocking() where possible. This is because
checking for __GFP_WAIT as was done historically now can trigger false
positives. Some exceptions like dm-crypt.c exist where the code intent
is clearer if __GFP_DIRECT_RECLAIM is used instead of the helper due to
flag manipulations.o Callers that built their own GFP flags instead of starting with GFP_KERNEL
and friends now also need to specify __GFP_KSWAPD_RECLAIM.The first key hazard to watch out for is callers that removed __GFP_WAIT
and was depending on access to atomic reserves for inconspicuous reasons.
In some cases it may be appropriate for them to use __GFP_HIGH.The second key hazard is callers that assembled their own combination of
GFP flags instead of starting with something like GFP_KERNEL. They may
now wish to specify __GFP_KSWAPD_RECLAIM. It's almost certainly harmless
if it's missed in most cases as other activity will wake kswapd.Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Vitaly Wool <vitalywool@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
21 Oct, 2015
1 commit
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a20135ffbc44 ("writeback: don't drain bdi_writeback_congested on bdi
destruction") added rbtree_postorder_for_each_entry_safe() which is
used to remove all entries; however, according to Cody, the iterator
isn't safe against operations which may rebalance the tree. Fix it by
switching to repeatedly removing rb_first() until empty.Signed-off-by: Tejun Heo
Reported-by: Cody P Schafer
Fixes: a20135ffbc44 ("writeback: don't drain bdi_writeback_congested on bdi destruction")
Link: http://lkml.kernel.org/g/1443997973-1700-1-git-send-email-dev@codyps.com
Signed-off-by: Jens Axboe
15 Oct, 2015
1 commit
-
bdi's are initialized in two steps, bdi_init() and bdi_register(), but
destroyed in a single step by bdi_destroy() which, for a bdi embedded
in a request_queue, is called during blk_cleanup_queue() which makes
the queue invisible and starts the draining of remaining usages.A request_queue's user can access the congestion state of the embedded
bdi as long as it holds a reference to the queue. As such, it may
access the congested state of a queue which finished
blk_cleanup_queue() but hasn't reached blk_release_queue() yet.
Because the congested state was embedded in backing_dev_info which in
turn is embedded in request_queue, accessing the congested state after
bdi_destroy() was called was fine. The bdi was destroyed but the
memory region for the congested state remained accessible till the
queue got released.a13f35e87140 ("writeback: don't embed root bdi_writeback_congested in
bdi_writeback") changed the situation. Now, the root congested state
which is expected to be pinned while request_queue remains accessible
is separately reference counted and the base ref is put during
bdi_destroy(). This means that the root congested state may go away
prematurely while the queue is between bdi_dstroy() and
blk_cleanup_queue(), which was detected by Andrey's KASAN tests.The root cause of this problem is that bdi doesn't distinguish the two
steps of destruction, unregistration and release, and now the root
congested state actually requires a separate release step. To fix the
issue, this patch separates out bdi_unregister() and bdi_exit() from
bdi_destroy(). bdi_unregister() is called from blk_cleanup_queue()
and bdi_exit() from blk_release_queue(). bdi_destroy() is now just a
simple wrapper calling the two steps back-to-back.While at it, the prototype of bdi_destroy() is moved right below
bdi_setup_and_register() so that the counterpart operations are
located together.Signed-off-by: Tejun Heo
Fixes: a13f35e87140 ("writeback: don't embed root bdi_writeback_congested in bdi_writeback")
Cc: stable@vger.kernel.org # v4.2+
Reported-and-tested-by: Andrey Konovalov
Link: http://lkml.kernel.org/g/CAAeHK+zUJ74Zn17=rOyxacHU18SgCfC6bsYW=6kCY5GXJBwGfQ@mail.gmail.com
Reviewed-by: Jan Kara
Reviewed-by: Jeff Moyer
Signed-off-by: Jens Axboe
13 Oct, 2015
1 commit
-
bdi_for_each_wb() is used in several places to wake up or issue
writeback work items to all wb's (bdi_writeback's) on a given bdi.
The iteration is performed by walking bdi->cgwb_tree; however, the
tree only indexes wb's which are currently active.For example, when a memcg gets associated with a different blkcg, the
old wb is removed from the tree so that the new one can be indexed.
The old wb starts dying from then on but will linger till all its
inodes are drained. As these dying wb's may still host dirty inodes,
writeback operations which affect all wb's must include them.
bdi_for_each_wb() skipping dying wb's led to sync(2) missing and
failing to sync the inodes belonging to those wb's.This patch adds a RCU protected @bdi->wb_list which lists all wb's
beloinging to that bdi. wb's are added on creation and removed on
release rather than on the start of destruction. bdi_for_each_wb()
usages are replaced with list_for_each[_continue]_rcu() iterations
over @bdi->wb_list and bdi_for_each_wb() and its helpers are removed.v2: Updated as per Jan. last_wb ref leak in bdi_split_work_to_wbs()
fixed and unnecessary list head severing in cgwb_bdi_destroy()
removed.Signed-off-by: Tejun Heo
Reported-and-tested-by: Artem Bityutskiy
Fixes: ebe41ab0c79d ("writeback: implement bdi_for_each_wb()")
Link: http://lkml.kernel.org/g/1443012552.19983.209.camel@gmail.com
Cc: Jan Kara
Signed-off-by: Jens Axboe
11 Sep, 2015
1 commit
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Pull blk-cg updates from Jens Axboe:
"A bit later in the cycle, but this has been in the block tree for a a
while. This is basically four patchsets from Tejun, that improve our
buffered cgroup writeback. It was dependent on the other cgroup
changes, but they went in earlier in this cycle.Series 1 is set of 5 patches that has cgroup writeback updates:
- bdi_writeback iteration fix which could lead to some wb's being
skipped or repeated during e.g. sync under memory pressure.- Simplification of wb work wait mechanism.
- Writeback tracepoints updated to report cgroup.
Series 2 is is a set of updates for the CFQ cgroup writeback handling:
cfq has always charged all async IOs to the root cgroup. It didn't
have much choice as writeback didn't know about cgroups and there
was no way to tell who to blame for a given writeback IO.
writeback finally grew support for cgroups and now tags each
writeback IO with the appropriate cgroup to charge it against.This patchset updates cfq so that it follows the blkcg each bio is
tagged with. Async cfq_queues are now shared across cfq_group,
which is per-cgroup, instead of per-request_queue cfq_data. This
makes all IOs follow the weight based IO resource distribution
implemented by cfq.- Switched from GFP_ATOMIC to GFP_NOWAIT as suggested by Jeff.
- Other misc review points addressed, acks added and rebased.
Series 3 is the blkcg policy cleanup patches:
This patchset contains assorted cleanups for blkcg_policy methods
and blk[c]g_policy_data handling.- alloc/free added for blkg_policy_data. exit dropped.
- alloc/free added for blkcg_policy_data.
- blk-throttle's async percpu allocation is replaced with direct
allocation.- all methods now take blk[c]g_policy_data instead of blkcg_gq or
blkcg.And finally, series 4 is a set of patches cleaning up the blkcg stats
handling:blkcg's stats have always been somwhat of a mess. This patchset
tries to improve the situation a bit.- The following patches added to consolidate blkcg entry point and
blkg creation. This is in itself is an improvement and helps
colllecting common stats on bio issue.- per-blkg stats now accounted on bio issue rather than request
completion so that bio based and request based drivers can behave
the same way. The issue was spotted by Vivek.- cfq-iosched implements custom recursive stats and blk-throttle
implements custom per-cpu stats. This patchset make blkcg core
support both by default.- cfq-iosched and blk-throttle keep track of the same stats
multiple times. Unify them"* 'for-4.3/blkcg' of git://git.kernel.dk/linux-block: (45 commits)
blkcg: use CGROUP_WEIGHT_* scale for io.weight on the unified hierarchy
blkcg: s/CFQ_WEIGHT_*/CFQ_WEIGHT_LEGACY_*/
blkcg: implement interface for the unified hierarchy
blkcg: misc preparations for unified hierarchy interface
blkcg: separate out tg_conf_updated() from tg_set_conf()
blkcg: move body parsing from blkg_conf_prep() to its callers
blkcg: mark existing cftypes as legacy
blkcg: rename subsystem name from blkio to io
blkcg: refine error codes returned during blkcg configuration
blkcg: remove unnecessary NULL checks from __cfqg_set_weight_device()
blkcg: reduce stack usage of blkg_rwstat_recursive_sum()
blkcg: remove cfqg_stats->sectors
blkcg: move io_service_bytes and io_serviced stats into blkcg_gq
blkcg: make blkg_[rw]stat_recursive_sum() to be able to index into blkcg_gq
blkcg: make blkcg_[rw]stat per-cpu
blkcg: add blkg_[rw]stat->aux_cnt and replace cfq_group->dead_stats with it
blkcg: consolidate blkg creation in blkcg_bio_issue_check()
blk-throttle: improve queue bypass handling
blkcg: move root blkg lookup optimization from throtl_lookup_tg() to __blkg_lookup()
blkcg: inline [__]blkg_lookup()
...
19 Aug, 2015
1 commit
-
blkio interface has become messy over time and is currently the
largest. In addition to the inconsistent naming scheme, it has
multiple stat files which report more or less the same thing, a number
of debug stat files which expose internal details which shouldn't have
been part of the public interface in the first place, recursive and
non-recursive stats and leaf and non-leaf knobs.Both recursive vs. non-recursive and leaf vs. non-leaf distinctions
don't make any sense on the unified hierarchy as only leaf cgroups can
contain processes. cgroups is going through a major interface
revision with the unified hierarchy involving significant fundamental
usage changes and given that a significant portion of the interface
doesn't make sense anymore, it's a good time to reorganize the
interface.As the first step, this patch renames the external visible subsystem
name from "blkio" to "io". This is more concise, matches the other
two major subsystem names, "cpu" and "memory", and better suited as
blkcg will be involved in anything writeback related too whether an
actual block device is involved or not.As the subsystem legacy_name is set to "blkio", the only userland
visible change outside the unified hierarchy is that blkcg is reported
as "io" instead of "blkio" in the subsystem initialized message during
boot. On the unified hierarchy, blkcg now appears as "io".Signed-off-by: Tejun Heo
Cc: Li Zefan
Cc: Johannes Weiner
Cc: cgroups@vger.kernel.org
Signed-off-by: Jens Axboe
18 Aug, 2015
1 commit
-
There's a small consistency problem between the inode and writeback
naming. Writeback calls the "for IO" inode queues b_io and
b_more_io, but the inode calls these the "writeback list" or
i_wb_list. This makes it hard to an new "under writeback" list to
the inode, or call it an "under IO" list on the bdi because either
way we'll have writeback on IO and IO on writeback and it'll just be
confusing. I'm getting confused just writing this!So, rename the inode "for IO" list variable to i_io_list so we can
add a new "writeback list" in a subsequent patch.Signed-off-by: Dave Chinner
Signed-off-by: Josef Bacik
Reviewed-by: Jan Kara
Reviewed-by: Christoph Hellwig
Tested-by: Dave Chinner
02 Jul, 2015
2 commits
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52ebea749aae ("writeback: make backing_dev_info host cgroup-specific
bdi_writebacks") made bdi (backing_dev_info) host per-cgroup wb's
(bdi_writeback's). As the congested state needs to be per-wb and
referenced from blkcg side and multiple wbs, the patch made all
non-root cong's (bdi_writeback_congested's) reference counted and
indexed on bdi.When a bdi is destroyed, cgwb_bdi_destroy() tries to drain all
non-root cong's; however, this can hang indefinitely because wb's can
also be referenced from blkcg_gq's which are destroyed after bdi
destruction is complete.This patch fixes the bug by updating bdi destruction to not wait for
cong's to drain. A cong is unlinked from bdi->cgwb_congested_tree on
bdi destuction regardless of its reference count as the bdi may go
away any point after destruction. wb_congested_put() checks whether
the cong is already unlinked on release.Signed-off-by: Tejun Heo
Reported-by: Jon Christopherson
Link: https://bugzilla.kernel.org/show_bug.cgi?id=100681
Fixes: 52ebea749aae ("writeback: make backing_dev_info host cgroup-specific bdi_writebacks")
Tested-by: Jon Christopherson
Signed-off-by: Jens Axboe -
52ebea749aae ("writeback: make backing_dev_info host cgroup-specific
bdi_writebacks") made bdi (backing_dev_info) host per-cgroup wb's
(bdi_writeback's). As the congested state needs to be per-wb and
referenced from blkcg side and multiple wbs, the patch made all
non-root cong's (bdi_writeback_congested's) reference counted and
indexed on bdi.When a bdi is destroyed, cgwb_bdi_destroy() tries to drain all
non-root cong's; however, this can hang indefinitely because wb's can
also be referenced from blkcg_gq's which are destroyed after bdi
destruction is complete.To fix the bug, bdi destruction will be updated to not wait for cong's
to drain, which naturally means that cong's may outlive the associated
bdi. This is fine for non-root cong's but is problematic for the root
cong's which are embedded in their bdi's as they may end up getting
dereferenced after the containing bdi's are freed.This patch makes root cong's behave the same as non-root cong's. They
are no longer embedded in their bdi's but allocated separately during
bdi initialization, indexed and reference counted the same way.* As cong handling is the same for all wb's, wb->congested
initialization is moved into wb_init().* When !CONFIG_CGROUP_WRITEBACK, there was no indexing or refcnting.
bdi->wb_congested is now a pointer pointing to the root cong
allocated during bdi init and minimal refcnting operations are
implemented.* The above makes root wb init paths diverge depending on
CONFIG_CGROUP_WRITEBACK. root wb init is moved to cgwb_bdi_init().This patch in itself shouldn't cause any consequential behavior
differences but prepares for the actual fix.Signed-off-by: Tejun Heo
Reported-by: Jon Christopherson
Link: https://bugzilla.kernel.org/show_bug.cgi?id=100681
Tested-by: Jon ChristophersonAdded include to backing-dev.h for kfree() definition.
Signed-off-by: Jens Axboe
26 Jun, 2015
1 commit
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Pull cgroup writeback support from Jens Axboe:
"This is the big pull request for adding cgroup writeback support.This code has been in development for a long time, and it has been
simmering in for-next for a good chunk of this cycle too. This is one
of those problems that has been talked about for at least half a
decade, finally there's a solution and code to go with it.Also see last weeks writeup on LWN:
http://lwn.net/Articles/648292/"
* 'for-4.2/writeback' of git://git.kernel.dk/linux-block: (85 commits)
writeback, blkio: add documentation for cgroup writeback support
vfs, writeback: replace FS_CGROUP_WRITEBACK with SB_I_CGROUPWB
writeback: do foreign inode detection iff cgroup writeback is enabled
v9fs: fix error handling in v9fs_session_init()
bdi: fix wrong error return value in cgwb_create()
buffer: remove unusued 'ret' variable
writeback: disassociate inodes from dying bdi_writebacks
writeback: implement foreign cgroup inode bdi_writeback switching
writeback: add lockdep annotation to inode_to_wb()
writeback: use unlocked_inode_to_wb transaction in inode_congested()
writeback: implement unlocked_inode_to_wb transaction and use it for stat updates
writeback: implement [locked_]inode_to_wb_and_lock_list()
writeback: implement foreign cgroup inode detection
writeback: make writeback_control track the inode being written back
writeback: relocate wb[_try]_get(), wb_put(), inode_{attach|detach}_wb()
mm: vmscan: disable memcg direct reclaim stalling if cgroup writeback support is in use
writeback: implement memcg writeback domain based throttling
writeback: reset wb_domain->dirty_limit[_tstmp] when memcg domain size changes
writeback: implement memcg wb_domain
writeback: update wb_over_bg_thresh() to use wb_domain aware operations
...
05 Jun, 2015
1 commit
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On wb_congested_get_create() failure, cgwb_create() forgot to set @ret
to -ENOMEM ending up returning 0. Fix it so that it returns -ENOMEM.Signed-off-by: Tejun Heo
Reported-by: Dan Carpenter
Signed-off-by: Jens Axboe
02 Jun, 2015
16 commits
-
Currently, majority of cgroup writeback support including all the
above functions are implemented in include/linux/backing-dev.h and
mm/backing-dev.c; however, the portion closely related to writeback
logic implemented in include/linux/writeback.h and mm/page-writeback.c
will expand to support foreign writeback detection and correction.This patch moves wb[_try]_get() and wb_put() to
include/linux/backing-dev-defs.h so that they can be used from
writeback.h and inode_{attach|detach}_wb() to writeback.h and
page-writeback.c.This is pure reorganization and doesn't introduce any functional
changes.Signed-off-by: Tejun Heo
Cc: Jens Axboe
Cc: Jan Kara
Cc: Wu Fengguang
Cc: Greg Thelen
Signed-off-by: Jens Axboe -
Dirtyable memory is distributed to a wb (bdi_writeback) according to
the relative bandwidth the wb is writing out in the whole system.
This distribution is global - each wb is measured against all other
wb's and gets the proportinately sized portion of the memory in the
whole system.For cgroup writeback, the amount of dirtyable memory is scoped by
memcg and thus each wb would need to be measured and controlled in its
memcg. IOW, a wb will belong to two writeback domains - the global
and memcg domains.The previous patches laid the groundwork to support the two wb_domains
and this patch implements memcg wb_domain. memcg->cgwb_domain is
initialized on css online and destroyed on css release,
wb->memcg_completions is added, and __wb_writeout_inc() is updated to
increment completions against both global and memcg wb_domains.The following patches will update balance_dirty_pages() and its
subroutines to actually consider memcg wb_domain for throttling.Signed-off-by: Tejun Heo
Cc: Jens Axboe
Cc: Jan Kara
Cc: Wu Fengguang
Cc: Greg Thelen
Signed-off-by: Jens Axboe -
The function name wb_dirty_limit(), its argument @dirty and the local
variable @wb_dirty are mortally confusing given that the function
calculates per-wb threshold value not dirty pages, especially given
that @dirty and @wb_dirty are used elsewhere for dirty pages.Let's rename the function to wb_calc_thresh() and wb_dirty to
wb_thresh.Signed-off-by: Tejun Heo
Cc: Jens Axboe
Cc: Jan Kara
Cc: Wu Fengguang
Cc: Greg Thelen
Signed-off-by: Jens Axboe -
If the completion of a wb_writeback_work can be waited upon by setting
its ->done to a struct completion and waiting on it; however, for
cgroup writeback support, it's necessary to issue multiple work items
to multiple bdi_writebacks and wait for the completion of all.This patch implements wb_completion which can wait for multiple work
items and replaces the struct completion with it. It can be defined
using DEFINE_WB_COMPLETION_ONSTACK(), used for multiple work items and
waited for by wb_wait_for_completion().Nobody currently issues multiple work items and this patch doesn't
introduce any behavior changes.Signed-off-by: Tejun Heo
Cc: Jens Axboe
Cc: Jan Kara
Signed-off-by: Jens Axboe -
bdi_has_dirty_io() used to only reflect whether the root wb
(bdi_writeback) has dirty inodes. For cgroup writeback support, it
needs to take all active wb's into account. If any wb on the bdi has
dirty inodes, bdi_has_dirty_io() should return true.To achieve that, as inode_wb_list_{move|del}_locked() now keep track
of the dirty state transition of each wb, the number of dirty wbs can
be counted in the bdi; however, bdi is already aggregating
wb->avg_write_bandwidth which can easily be guaranteed to be > 0 when
there are any dirty inodes by ensuring wb->avg_write_bandwidth can't
dip below 1. bdi_has_dirty_io() can simply test whether
bdi->tot_write_bandwidth is zero or not.While this bumps the value of wb->avg_write_bandwidth to one when it
used to be zero, this shouldn't cause any meaningful behavior
difference.bdi_has_dirty_io() is made an inline function which tests whether
->tot_write_bandwidth is non-zero. Also, WARN_ON_ONCE()'s on its
value are added to inode_wb_list_{move|del}_locked().Signed-off-by: Tejun Heo
Cc: Jens Axboe
Cc: Jan Kara
Signed-off-by: Jens Axboe -
Currently, wb_has_dirty_io() determines whether a wb (bdi_writeback)
has any dirty inode by testing all three IO lists on each invocation
without actively keeping track. For cgroup writeback support, a
single bdi will host multiple wb's each of which will host dirty
inodes separately and we'll need to make bdi_has_dirty_io(), which
currently only represents the root wb, aggregate has_dirty_io from all
member wb's, which requires tracking transitions in has_dirty_io state
on each wb.This patch introduces inode_wb_list_{move|del}_locked() to consolidate
IO list operations leaving queue_io() the only other function which
directly manipulates IO lists (via move_expired_inodes()). All three
functions are updated to call wb_io_lists_[de]populated() which keep
track of whether the wb has dirty inodes or not and record it using
the new WB_has_dirty_io flag. inode_wb_list_moved_locked()'s return
value indicates whether the wb had no dirty inodes before.mark_inode_dirty() is restructured so that the return value of
inode_wb_list_move_locked() can be used for deciding whether to wake
up the wb.While at it, change {bdi|wb}_has_dirty_io()'s return values to bool.
These functions were returning 0 and 1 before. Also, add a comment
explaining the synchronization of wb_state flags.v2: Updated to accommodate b_dirty_time.
Signed-off-by: Tejun Heo
Cc: Jens Axboe
Cc: Jan Kara
Signed-off-by: Jens Axboe -
Currently, all congestion functions take bdi (backing_dev_info) and
always operate on the root wb (bdi->wb) and the congestion state from
the block layer is propagated only for the root blkcg. This patch
introduces {set|clear}_wb_congested() and wb_congested() which take a
bdi_writeback_congested and bdi_writeback respectively. The bdi
counteparts are now wrappers invoking the wb based functions on
@bdi->wb.While converting clear_bdi_congested() to clear_wb_congested(), the
local variable declaration order between @wqh and @bit is swapped for
cosmetic reason.This patch just adds the new wb based functions. The following
patches will apply them.v2: Updated for bdi_writeback_congested.
Signed-off-by: Tejun Heo
Reviewed-by: Jan Kara
Cc: Jens Axboe
Signed-off-by: Jens Axboe -
For the planned cgroup writeback support, on each bdi
(backing_dev_info), each memcg will be served by a separate wb
(bdi_writeback). This patch updates bdi so that a bdi can host
multiple wbs (bdi_writebacks).On the default hierarchy, blkcg implicitly enables memcg. This allows
using memcg's page ownership for attributing writeback IOs, and every
memcg - blkcg combination can be served by its own wb by assigning a
dedicated wb to each memcg. This means that there may be multiple
wb's of a bdi mapped to the same blkcg. As congested state is per
blkcg - bdi combination, those wb's should share the same congested
state. This is achieved by tracking congested state via
bdi_writeback_congested structs which are keyed by blkcg.bdi->wb remains unchanged and will keep serving the root cgroup.
cgwb's (cgroup wb's) for non-root cgroups are created on-demand or
looked up while dirtying an inode according to the memcg of the page
being dirtied or current task. Each cgwb is indexed on bdi->cgwb_tree
by its memcg id. Once an inode is associated with its wb, it can be
retrieved using inode_to_wb().Currently, none of the filesystems has FS_CGROUP_WRITEBACK and all
pages will keep being associated with bdi->wb.v3: inode_attach_wb() in account_page_dirtied() moved inside
mapping_cap_account_dirty() block where it's known to be !NULL.
Also, an unnecessary NULL check before kfree() removed. Both
detected by the kbuild bot.v2: Updated so that wb association is per inode and wb is per memcg
rather than blkcg.Signed-off-by: Tejun Heo
Cc: kbuild test robot
Cc: Dan Carpenter
Cc: Jens Axboe
Cc: Jan Kara
Signed-off-by: Jens Axboe -
Currently, a wb's (bdi_writeback) congestion state is carried in its
->state field; however, cgroup writeback support will require multiple
wb's sharing the same congestion state. This patch separates out
congestion state into its own struct - struct bdi_writeback_congested.
A new field wb field, wb_congested, points to its associated congested
struct. The default wb, bdi->wb, always points to bdi->wb_congested.While this patch adds a layer of indirection, it doesn't introduce any
behavior changes.Signed-off-by: Tejun Heo
Signed-off-by: Jens Axboe -
wb_init() currently always uses GFP_KERNEL but the planned cgroup
writeback support needs using other allocation masks. Add @gfp to
wb_init().This patch doesn't introduce any behavior changes.
Signed-off-by: Tejun Heo
Reviewed-by: Jan Kara
Cc: Jens Axboe
Signed-off-by: Jens Axboe -
Now that bdi definitions are moved to backing-dev-defs.h,
backing-dev.h can include blkdev.h and inline inode_to_bdi() without
worrying about introducing circular include dependency. The function
gets called from hot paths and fairly trivial.This patch makes inode_to_bdi() and sb_is_blkdev_sb() that the
function calls inline. blockdev_superblock and noop_backing_dev_info
are EXPORT_GPL'd to allow the inline functions to be used from
modules.While at it, make sb_is_blkdev_sb() return bool instead of int.
v2: Fixed typo in description as suggested by Jan.
Signed-off-by: Tejun Heo
Reviewed-by: Jens Axboe
Cc: Christoph Hellwig
Signed-off-by: Jens Axboe -
Move wb_shutdown(), bdi_register(), bdi_register_dev(),
bdi_prune_sb(), bdi_remove_from_list() and bdi_unregister() so that
init / exit functions are grouped together. This will make updating
init / exit paths for cgroup writeback support easier.This is pure source file reorganization.
Signed-off-by: Tejun Heo
Reviewed-by: Jan Kara
Cc: Jens Axboe
Cc: Wu Fengguang
Signed-off-by: Jens Axboe -
Currently, a bdi (backing_dev_info) embeds single wb (bdi_writeback)
and the role of the separation is unclear. For cgroup support for
writeback IOs, a bdi will be updated to host multiple wb's where each
wb serves writeback IOs of a different cgroup on the bdi. To achieve
that, a wb should carry all states necessary for servicing writeback
IOs for a cgroup independently.This patch moves bdi->wb_lock and ->worklist into wb.
* The lock protects bdi->worklist and bdi->wb.dwork scheduling. While
moving, rename it to wb->work_lock as wb->wb_lock is confusing.
Also, move wb->dwork downwards so that it's colocated with the new
->work_lock and ->work_list fields.* bdi_writeback_workfn() -> wb_workfn()
bdi_wakeup_thread_delayed(bdi) -> wb_wakeup_delayed(wb)
bdi_wakeup_thread(bdi) -> wb_wakeup(wb)
bdi_queue_work(bdi, ...) -> wb_queue_work(wb, ...)
__bdi_start_writeback(bdi, ...) -> __wb_start_writeback(wb, ...)
get_next_work_item(bdi) -> get_next_work_item(wb)* bdi_wb_shutdown() is renamed to wb_shutdown() and now takes @wb.
The function contained parts which belong to the containing bdi
rather than the wb itself - testing cap_writeback_dirty and
bdi_remove_from_list() invocation. Those are moved to
bdi_unregister().* bdi_wb_{init|exit}() are renamed to wb_{init|exit}().
Initializations of the moved bdi->wb_lock and ->work_list are
relocated from bdi_init() to wb_init().* As there's still only one bdi_writeback per backing_dev_info, all
uses of bdi->state are mechanically replaced with bdi->wb.state
introducing no behavior changes.Signed-off-by: Tejun Heo
Reviewed-by: Jan Kara
Cc: Jens Axboe
Cc: Wu Fengguang
Signed-off-by: Jens Axboe -
Currently, a bdi (backing_dev_info) embeds single wb (bdi_writeback)
and the role of the separation is unclear. For cgroup support for
writeback IOs, a bdi will be updated to host multiple wb's where each
wb serves writeback IOs of a different cgroup on the bdi. To achieve
that, a wb should carry all states necessary for servicing writeback
IOs for a cgroup independently.This patch moves bandwidth related fields from backing_dev_info into
bdi_writeback.* The moved fields are: bw_time_stamp, dirtied_stamp, written_stamp,
write_bandwidth, avg_write_bandwidth, dirty_ratelimit,
balanced_dirty_ratelimit, completions and dirty_exceeded.* writeback_chunk_size() and over_bground_thresh() now take @wb
instead of @bdi.* bdi_writeout_fraction(bdi, ...) -> wb_writeout_fraction(wb, ...)
bdi_dirty_limit(bdi, ...) -> wb_dirty_limit(wb, ...)
bdi_position_ration(bdi, ...) -> wb_position_ratio(wb, ...)
bdi_update_writebandwidth(bdi, ...) -> wb_update_write_bandwidth(wb, ...)
[__]bdi_update_bandwidth(bdi, ...) -> [__]wb_update_bandwidth(wb, ...)
bdi_{max|min}_pause(bdi, ...) -> wb_{max|min}_pause(wb, ...)
bdi_dirty_limits(bdi, ...) -> wb_dirty_limits(wb, ...)* Init/exits of the relocated fields are moved to bdi_wb_init/exit()
respectively. Note that explicit zeroing is dropped in the process
as wb's are cleared in entirety anyway.* As there's still only one bdi_writeback per backing_dev_info, all
uses of bdi->stat[] are mechanically replaced with bdi->wb.stat[]
introducing no behavior changes.v2: Typo in description fixed as suggested by Jan.
Signed-off-by: Tejun Heo
Reviewed-by: Jan Kara
Cc: Jens Axboe
Cc: Wu Fengguang
Cc: Jaegeuk Kim
Cc: Steven Whitehouse
Signed-off-by: Jens Axboe -
Currently, a bdi (backing_dev_info) embeds single wb (bdi_writeback)
and the role of the separation is unclear. For cgroup support for
writeback IOs, a bdi will be updated to host multiple wb's where each
wb serves writeback IOs of a different cgroup on the bdi. To achieve
that, a wb should carry all states necessary for servicing writeback
IOs for a cgroup independently.This patch moves bdi->bdi_stat[] into wb.
* enum bdi_stat_item is renamed to wb_stat_item and the prefix of all
enums is changed from BDI_ to WB_.* BDI_STAT_BATCH() -> WB_STAT_BATCH()
* [__]{add|inc|dec|sum}_wb_stat(bdi, ...) -> [__]{add|inc}_wb_stat(wb, ...)
* bdi_stat[_error]() -> wb_stat[_error]()
* bdi_writeout_inc() -> wb_writeout_inc()
* stat init is moved to bdi_wb_init() and bdi_wb_exit() is added and
frees stat.* As there's still only one bdi_writeback per backing_dev_info, all
uses of bdi->stat[] are mechanically replaced with bdi->wb.stat[]
introducing no behavior changes.Signed-off-by: Tejun Heo
Reviewed-by: Jan Kara
Cc: Jens Axboe
Cc: Wu Fengguang
Cc: Miklos Szeredi
Cc: Trond Myklebust
Signed-off-by: Jens Axboe -
Currently, a bdi (backing_dev_info) embeds single wb (bdi_writeback)
and the role of the separation is unclear. For cgroup support for
writeback IOs, a bdi will be updated to host multiple wb's where each
wb serves writeback IOs of a different cgroup on the bdi. To achieve
that, a wb should carry all states necessary for servicing writeback
IOs for a cgroup independently.This patch moves bdi->state into wb.
* enum bdi_state is renamed to wb_state and the prefix of all enums is
changed from BDI_ to WB_.* Explicit zeroing of bdi->state is removed without adding zeoring of
wb->state as the whole data structure is zeroed on init anyway.* As there's still only one bdi_writeback per backing_dev_info, all
uses of bdi->state are mechanically replaced with bdi->wb.state
introducing no behavior changes.Signed-off-by: Tejun Heo
Reviewed-by: Jan Kara
Cc: Jens Axboe
Cc: Wu Fengguang
Cc: drbd-dev@lists.linbit.com
Cc: Neil Brown
Cc: Alasdair Kergon
Cc: Mike Snitzer
Signed-off-by: Jens Axboe
29 May, 2015
1 commit
-
bdi_unregister() now contains very little functionality.
It contains a "WARN_ON" if bdi->dev is NULL. This warning is of no
real consequence as bdi->dev isn't needed by anything else in the function,
and it triggers if
blk_cleanup_queue() -> bdi_destroy()
is called before bdi_unregister, which happens since
Commit: 6cd18e711dd8 ("block: destroy bdi before blockdev is unregistered.")So this isn't wanted.
It also calls bdi_set_min_ratio(). This needs to be called after
writes through the bdi have all been flushed, and before the bdi is destroyed.
Calling it early is better than calling it late as it frees up a global
resource.Calling it immediately after bdi_wb_shutdown() in bdi_destroy()
perfectly fits these requirements.So bdi_unregister() can be discarded with the important content moved to
bdi_destroy(), as can the
writeback_bdi_unregister
event which is already not used.Reported-by: Mike Snitzer
Cc: stable@vger.kernel.org (v4.0)
Fixes: c4db59d31e39 ("fs: don't reassign dirty inodes to default_backing_dev_info")
Fixes: 6cd18e711dd8 ("block: destroy bdi before blockdev is unregistered.")
Acked-by: Peter Zijlstra (Intel)
Acked-by: Dan Williams
Tested-by: Nicholas Moulin
Signed-off-by: NeilBrown
Reviewed-by: Christoph Hellwig
Signed-off-by: Jens Axboe
18 Feb, 2015
1 commit
-
Pull lazytime mount option support from Al Viro:
"Lazytime stuff from tytso"* 'lazytime' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
ext4: add optimization for the lazytime mount option
vfs: add find_inode_nowait() function
vfs: add support for a lazytime mount option
05 Feb, 2015
1 commit
-
Add a new mount option which enables a new "lazytime" mode. This mode
causes atime, mtime, and ctime updates to only be made to the
in-memory version of the inode. The on-disk times will only get
updated when (a) if the inode needs to be updated for some non-time
related change, (b) if userspace calls fsync(), syncfs() or sync(), or
(c) just before an undeleted inode is evicted from memory.This is OK according to POSIX because there are no guarantees after a
crash unless userspace explicitly requests via a fsync(2) call.For workloads which feature a large number of random write to a
preallocated file, the lazytime mount option significantly reduces
writes to the inode table. The repeated 4k writes to a single block
will result in undesirable stress on flash devices and SMR disk
drives. Even on conventional HDD's, the repeated writes to the inode
table block will trigger Adjacent Track Interference (ATI) remediation
latencies, which very negatively impact long tail latencies --- which
is a very big deal for web serving tiers (for example).Google-Bug-Id: 18297052
Signed-off-by: Theodore Ts'o
Signed-off-by: Al Viro
21 Jan, 2015
1 commit
-
Now that default_backing_dev_info is not used for writeback purposes we can
git rid of it easily:- instead of using it's name for tracing unregistered bdi we just use
"unknown"
- btrfs and ceph can just assign the default read ahead window themselves
like several other filesystems already do.
- we can assign noop_backing_dev_info as the default one in alloc_super.
All filesystems already either assigned their own or
noop_backing_dev_info.Signed-off-by: Christoph Hellwig
Reviewed-by: Tejun Heo
Reviewed-by: Jan Kara
Signed-off-by: Jens Axboe
