Revision tags: v6.6.25, v6.6.24, v6.6.23, v6.6.16, v6.6.15, v6.6.14 |
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601b5540 |
| 23-Jan-2024 |
Jan Kara <jack@suse.cz> |
blk-wbt: Fix detection of dirty-throttled tasks
commit f814bdda774c183b0cc15ec8f3b6e7c6f4527ba5 upstream.
The detection of dirty-throttled tasks in blk-wbt has been subtly broken since its beginnin
blk-wbt: Fix detection of dirty-throttled tasks
commit f814bdda774c183b0cc15ec8f3b6e7c6f4527ba5 upstream.
The detection of dirty-throttled tasks in blk-wbt has been subtly broken since its beginning in 2016. Namely if we are doing cgroup writeback and the throttled task is not in the root cgroup, balance_dirty_pages() will set dirty_sleep for the non-root bdi_writeback structure. However blk-wbt checks dirty_sleep only in the root cgroup bdi_writeback structure. Thus detection of recently throttled tasks is not working in this case (we noticed this when we switched to cgroup v2 and suddently writeback was slow).
Since blk-wbt has no easy way to get to proper bdi_writeback and furthermore its intention has always been to work on the whole device rather than on individual cgroups, just move the dirty_sleep timestamp from bdi_writeback to backing_dev_info. That fixes the checking for recently throttled task and saves memory for everybody as a bonus.
CC: stable@vger.kernel.org Fixes: b57d74aff9ab ("writeback: track if we're sleeping on progress in balance_dirty_pages()") Signed-off-by: Jan Kara <jack@suse.cz> Link: https://lore.kernel.org/r/20240123175826.21452-1-jack@suse.cz [axboe: fixup indentation errors] Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Revision tags: v6.6.13, v6.6.12, v6.6.11, v6.6.10, v6.6.9, v6.6.8, v6.6.7, v6.6.6, v6.6.5, v6.6.4, v6.6.3, v6.6.2, v6.5.11, v6.6.1, v6.5.10, v6.6, v6.5.9, v6.5.8, v6.5.7, v6.5.6, v6.5.5, v6.5.4, v6.5.3, v6.5.2, v6.1.51, v6.5.1, v6.1.50, v6.5, v6.1.49, v6.1.48, v6.1.46, v6.1.45, v6.1.44 |
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9af7c742 |
| 08-Aug-2023 |
Jinliang Zheng <alexjlzheng@tencent.com> |
writeback: remove redundant checks for root memcg
The check for root memcg will be done in wb_get_lookup(), so remove the redundant one to simplify the code.
Link: https://lkml.kernel.org/r/2023080
writeback: remove redundant checks for root memcg
The check for root memcg will be done in wb_get_lookup(), so remove the redundant one to simplify the code.
Link: https://lkml.kernel.org/r/20230808084431.1632934-1-alexjlzheng@tencent.com Signed-off-by: Jinliang Zheng <alexjlzheng@tencent.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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61f29738 |
| 03-Aug-2023 |
ZhangPeng <zhangpeng362@huawei.com> |
mm: remove redundant K() macro definition
Patch series "cleanup with helper macro K()".
Use helper macro K() to improve code readability. No functional modification involved. Remove redundant K()
mm: remove redundant K() macro definition
Patch series "cleanup with helper macro K()".
Use helper macro K() to improve code readability. No functional modification involved. Remove redundant K() macro definition.
This patch (of 7):
Since commit eb8589b4f8c1 ("mm: move mem_init_print_info() to mm_init.c"), the K() macro definition has been moved to mm/internal.h. Therefore, the definitions in mm/memcontrol.c, mm/backing-dev.c and mm/oom_kill.c are redundant. Drop redundant definitions.
[akpm@linux-foundation.org: oom_kill.c: remove "#undef K", per Kefeng] Link: https://lkml.kernel.org/r/20230804012559.2617515-1-zhangpeng362@huawei.com Link: https://lkml.kernel.org/r/20230804012559.2617515-2-zhangpeng362@huawei.com Signed-off-by: ZhangPeng <zhangpeng362@huawei.com> Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: David Hildenbrand <david@redhat.com> Cc: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Nanyong Sun <sunnanyong@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Revision tags: v6.1.43, v6.1.42, v6.1.41, v6.1.40, v6.1.39, v6.1.38, v6.1.37, v6.1.36, v6.4, v6.1.35 |
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b5665cf9 |
| 20-Jun-2023 |
Ivan Orlov <ivan.orlov0322@gmail.com> |
mm: backing-dev: make bdi_class a static const structure
Now that the driver core allows for struct class to be in read-only memory, move the bdi_class structure to be declared at build time placing
mm: backing-dev: make bdi_class a static const structure
Now that the driver core allows for struct class to be in read-only memory, move the bdi_class structure to be declared at build time placing it into read-only memory, instead of having to be dynamically allocated at load time.
Link: https://lkml.kernel.org/r/20230620183314.682822-2-gregkh@linuxfoundation.org Signed-off-by: Ivan Orlov <ivan.orlov0322@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Revision tags: v6.1.34, v6.1.33, v6.1.32, v6.1.31, v6.1.30, v6.1.29, v6.1.28, v6.1.27, v6.1.26, v6.3, v6.1.25, v6.1.24 |
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f6365881 |
| 08-Apr-2023 |
Tom Rix <trix@redhat.com> |
mm: backing-dev: set variables dev_attr_min,max_bytes storage-class-specifier to static
smatch reports mm/backing-dev.c:266:1: warning: symbol 'dev_attr_min_bytes' was not declared. Should it be s
mm: backing-dev: set variables dev_attr_min,max_bytes storage-class-specifier to static
smatch reports mm/backing-dev.c:266:1: warning: symbol 'dev_attr_min_bytes' was not declared. Should it be static? mm/backing-dev.c:294:1: warning: symbol 'dev_attr_max_bytes' was not declared. Should it be static?
These variables are only used in one file so should be static.
Link: https://lkml.kernel.org/r/20230408141609.2703647-1-trix@redhat.com Signed-off-by: Tom Rix <trix@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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1ba1199e |
| 10-Apr-2023 |
Baokun Li <libaokun1@huawei.com> |
writeback, cgroup: fix null-ptr-deref write in bdi_split_work_to_wbs
KASAN report null-ptr-deref: ================================================================== BUG: KASAN: null-ptr-deref in bdi
writeback, cgroup: fix null-ptr-deref write in bdi_split_work_to_wbs
KASAN report null-ptr-deref: ================================================================== BUG: KASAN: null-ptr-deref in bdi_split_work_to_wbs+0x5c5/0x7b0 Write of size 8 at addr 0000000000000000 by task sync/943 CPU: 5 PID: 943 Comm: sync Tainted: 6.3.0-rc5-next-20230406-dirty #461 Call Trace: <TASK> dump_stack_lvl+0x7f/0xc0 print_report+0x2ba/0x340 kasan_report+0xc4/0x120 kasan_check_range+0x1b7/0x2e0 __kasan_check_write+0x24/0x40 bdi_split_work_to_wbs+0x5c5/0x7b0 sync_inodes_sb+0x195/0x630 sync_inodes_one_sb+0x3a/0x50 iterate_supers+0x106/0x1b0 ksys_sync+0x98/0x160 [...] ==================================================================
The race that causes the above issue is as follows:
cpu1 cpu2 -------------------------|------------------------- inode_switch_wbs INIT_WORK(&isw->work, inode_switch_wbs_work_fn) queue_rcu_work(isw_wq, &isw->work) // queue_work async inode_switch_wbs_work_fn wb_put_many(old_wb, nr_switched) percpu_ref_put_many ref->data->release(ref) cgwb_release queue_work(cgwb_release_wq, &wb->release_work) // queue_work async &wb->release_work cgwb_release_workfn ksys_sync iterate_supers sync_inodes_one_sb sync_inodes_sb bdi_split_work_to_wbs kmalloc(sizeof(*work), GFP_ATOMIC) // alloc memory failed percpu_ref_exit ref->data = NULL kfree(data) wb_get(wb) percpu_ref_get(&wb->refcnt) percpu_ref_get_many(ref, 1) atomic_long_add(nr, &ref->data->count) atomic64_add(i, v) // trigger null-ptr-deref
bdi_split_work_to_wbs() traverses &bdi->wb_list to split work into all wbs. If the allocation of new work fails, the on-stack fallback will be used and the reference count of the current wb is increased afterwards. If cgroup writeback membership switches occur before getting the reference count and the current wb is released as old_wd, then calling wb_get() or wb_put() will trigger the null pointer dereference above.
This issue was introduced in v4.3-rc7 (see fix tag1). Both sync_inodes_sb() and __writeback_inodes_sb_nr() calls to bdi_split_work_to_wbs() can trigger this issue. For scenarios called via sync_inodes_sb(), originally commit 7fc5854f8c6e ("writeback: synchronize sync(2) against cgroup writeback membership switches") reduced the possibility of the issue by adding wb_switch_rwsem, but in v5.14-rc1 (see fix tag2) removed the "inode_io_list_del_locked(inode, old_wb)" from inode_switch_wbs_work_fn() so that wb->state contains WB_has_dirty_io, thus old_wb is not skipped when traversing wbs in bdi_split_work_to_wbs(), and the issue becomes easily reproducible again.
To solve this problem, percpu_ref_exit() is called under RCU protection to avoid race between cgwb_release_workfn() and bdi_split_work_to_wbs(). Moreover, replace wb_get() with wb_tryget() in bdi_split_work_to_wbs(), and skip the current wb if wb_tryget() fails because the wb has already been shutdown.
Link: https://lkml.kernel.org/r/20230410130826.1492525-1-libaokun1@huawei.com Fixes: b817525a4a80 ("writeback: bdi_writeback iteration must not skip dying ones") Signed-off-by: Baokun Li <libaokun1@huawei.com> Reviewed-by: Jan Kara <jack@suse.cz> Acked-by: Tejun Heo <tj@kernel.org> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Andreas Dilger <adilger.kernel@dilger.ca> Cc: Christian Brauner <brauner@kernel.org> Cc: Dennis Zhou <dennis@kernel.org> Cc: Hou Tao <houtao1@huawei.com> Cc: yangerkun <yangerkun@huawei.com> Cc: Zhang Yi <yi.zhang@huawei.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Revision tags: v6.1.23, v6.1.22, v6.1.21, v6.1.20 |
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1aaba11d |
| 13-Mar-2023 |
Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
driver core: class: remove module * from class_create()
The module pointer in class_create() never actually did anything, and it shouldn't have been requred to be set as a parameter even if it did s
driver core: class: remove module * from class_create()
The module pointer in class_create() never actually did anything, and it shouldn't have been requred to be set as a parameter even if it did something. So just remove it and fix up all callers of the function in the kernel tree at the same time.
Cc: "Rafael J. Wysocki" <rafael@kernel.org> Acked-by: Benjamin Tissoires <benjamin.tissoires@redhat.com> Link: https://lore.kernel.org/r/20230313181843.1207845-4-gregkh@linuxfoundation.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Revision tags: v6.1.19, v6.1.18, v6.1.17, v6.1.16, v6.1.15, v6.1.14, v6.1.13, v6.2, v6.1.12, v6.1.11, v6.1.10, v6.1.9, v6.1.8, v6.1.7, v6.1.6, v6.1.5, v6.0.19, v6.0.18, v6.1.4, v6.1.3, v6.0.17, v6.1.2, v6.0.16, v6.1.1, v6.0.15, v6.0.14, v6.0.13, v6.1, v6.0.12, v6.0.11, v6.0.10, v5.15.80 |
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ad3e6dab |
| 18-Nov-2022 |
Stefan Roesch <shr@devkernel.io> |
mm: add /sys/class/bdi/<bdi>/min_ratio_fine knob
This adds the min_ratio_fine knob. The knob specifies the values not based on 1 of 100, but instead 1 per million.
Link: https://lkml.kernel.org/r/2
mm: add /sys/class/bdi/<bdi>/min_ratio_fine knob
This adds the min_ratio_fine knob. The knob specifies the values not based on 1 of 100, but instead 1 per million.
Link: https://lkml.kernel.org/r/20221119005215.3052436-20-shr@devkernel.io Signed-off-by: Stefan Roesch <shr@devkernel.io> Cc: Chris Mason <clm@meta.com> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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bca52dcb |
| 18-Nov-2022 |
Stefan Roesch <shr@devkernel.io> |
mm: add /sys/class/bdi/<bdi>/max_ratio_fine knob
This adds the max_ratio_fine knob. The knob specifies the values not based on 1 of 100, but instead 1 per million.
Link: https://lkml.kernel.org/r/2
mm: add /sys/class/bdi/<bdi>/max_ratio_fine knob
This adds the max_ratio_fine knob. The knob specifies the values not based on 1 of 100, but instead 1 per million.
Link: https://lkml.kernel.org/r/20221119005215.3052436-17-shr@devkernel.io Signed-off-by: Stefan Roesch <shr@devkernel.io> Cc: Chris Mason <clm@meta.com> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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9c84819b |
| 18-Nov-2022 |
Stefan Roesch <shr@devkernel.io> |
mm: add /sys/class/bdi/<bdi>/min_bytes knob
bdi has two existing knobs to limit the amount of dirty memory: min_ratio and max_ratio. However the granularity of the knobs is limited and often it is m
mm: add /sys/class/bdi/<bdi>/min_bytes knob
bdi has two existing knobs to limit the amount of dirty memory: min_ratio and max_ratio. However the granularity of the knobs is limited and often it is more convenient to specify limits in terms of bytes. This change adds the min_bytes knob.
It does not store the min_bytes value, instead it converts the max_bytes value to a ratio. The value is therefore more an approximation than an absolute value.
It also maintains the sum over all the bdi min_ratio values stored in the variable bdi_min_ratio.
Link: https://lkml.kernel.org/r/20221119005215.3052436-14-shr@devkernel.io Signed-off-by: Stefan Roesch <shr@devkernel.io> Cc: Chris Mason <clm@meta.com> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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c56e049a |
| 18-Nov-2022 |
Stefan Roesch <shr@devkernel.io> |
mm: add knob /sys/class/bdi/<bdi>/max_bytes
This adds the new knob max_bytes to specify a dirty memory limit for the corresponding bdi. The specified bytes value is converted to a ratio.
Link: http
mm: add knob /sys/class/bdi/<bdi>/max_bytes
This adds the new knob max_bytes to specify a dirty memory limit for the corresponding bdi. The specified bytes value is converted to a ratio.
Link: https://lkml.kernel.org/r/20221119005215.3052436-9-shr@devkernel.io Signed-off-by: Stefan Roesch <shr@devkernel.io> Cc: Chris Mason <clm@meta.com> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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ae82291e |
| 18-Nov-2022 |
Stefan Roesch <shr@devkernel.io> |
mm: use part per 1000000 for bdi ratios
To get finer granularity for ratio calculations use part per million instead of percentiles. This is especially important if we want to automatically convert
mm: use part per 1000000 for bdi ratios
To get finer granularity for ratio calculations use part per million instead of percentiles. This is especially important if we want to automatically convert byte values to ratios. Otherwise the values that are actually used can be quite different. This is also important for machines with more main memory (1% of 256GB is already 2.5GB).
Link: https://lkml.kernel.org/r/20221119005215.3052436-5-shr@devkernel.io Signed-off-by: Stefan Roesch <shr@devkernel.io> Cc: Chris Mason <clm@meta.com> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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27bbe9d4 |
| 18-Nov-2022 |
Stefan Roesch <shr@devkernel.io> |
mm: add knob /sys/class/bdi/<bdi>/strict_limit
Add a new knob to /sys/class/bdi/<bdi>/strict_limit. This new knob allows to set/unset the flag BDI_CAP_STRICTLIMIT in the bdi capabilities.
Link: htt
mm: add knob /sys/class/bdi/<bdi>/strict_limit
Add a new knob to /sys/class/bdi/<bdi>/strict_limit. This new knob allows to set/unset the flag BDI_CAP_STRICTLIMIT in the bdi capabilities.
Link: https://lkml.kernel.org/r/20221119005215.3052436-3-shr@devkernel.io Signed-off-by: Stefan Roesch <shr@devkernel.io> Cc: Chris Mason <clm@meta.com> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Revision tags: v6.0.9, v5.15.79, v6.0.8, v5.15.78, v6.0.7, v5.15.77, v5.15.76, v6.0.6, v6.0.5, v5.15.75, v6.0.4, v6.0.3, v6.0.2, v5.15.74, v5.15.73, v6.0.1, v5.15.72, v6.0, v5.15.71, v5.15.70, v5.15.69, v5.15.68, v5.15.67, v5.15.66, v5.15.65, v5.15.64 |
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3083da7b |
| 26-Aug-2022 |
ye xingchen <ye.xingchen@zte.com.cn> |
mm: backing-dev: Remove the unneeded result variable
Return the value cgwb_bdi_init() directly instead of storing it in another redundant variable.
Link: https://lkml.kernel.org/r/20220826071906.25
mm: backing-dev: Remove the unneeded result variable
Return the value cgwb_bdi_init() directly instead of storing it in another redundant variable.
Link: https://lkml.kernel.org/r/20220826071906.252419-1-ye.xingchen@zte.com.cn Signed-off-by: ye xingchen <ye.xingchen@zte.com.cn> Reported-by: Zeal Robot <zealci@zte.com.cn> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Revision tags: v5.15.63, v5.15.62, v5.15.61, v5.15.60, v5.15.59 |
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f87904c0 |
| 01-Aug-2022 |
Khazhismel Kumykov <khazhy@chromium.org> |
writeback: avoid use-after-free after removing device
When a disk is removed, bdi_unregister gets called to stop further writeback and wait for associated delayed work to complete. However, wb_inod
writeback: avoid use-after-free after removing device
When a disk is removed, bdi_unregister gets called to stop further writeback and wait for associated delayed work to complete. However, wb_inode_writeback_end() may schedule bandwidth estimation dwork after this has completed, which can result in the timer attempting to access the just freed bdi_writeback.
Fix this by checking if the bdi_writeback is alive, similar to when scheduling writeback work.
Since this requires wb->work_lock, and wb_inode_writeback_end() may get called from interrupt, switch wb->work_lock to an irqsafe lock.
Link: https://lkml.kernel.org/r/20220801155034.3772543-1-khazhy@google.com Fixes: 45a2966fd641 ("writeback: fix bandwidth estimate for spiky workload") Signed-off-by: Khazhismel Kumykov <khazhy@google.com> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Michael Stapelberg <stapelberg+linux@google.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Revision tags: v5.19, v5.15.58, v5.15.57, v5.15.56, v5.15.55, v5.15.54, v5.15.53, v5.15.52, v5.15.51, v5.15.50, v5.15.49, v5.15.48 |
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4bca7e80 |
| 15-Jun-2022 |
Jan Kara <jack@suse.cz> |
init: Initialize noop_backing_dev_info early
noop_backing_dev_info is used by superblocks of various pseudofilesystems such as kdevtmpfs. After commit 10e14073107d ("writeback: Fix inode->i_io_list
init: Initialize noop_backing_dev_info early
noop_backing_dev_info is used by superblocks of various pseudofilesystems such as kdevtmpfs. After commit 10e14073107d ("writeback: Fix inode->i_io_list not be protected by inode->i_lock error") this broke because __mark_inode_dirty() started to access more fields from noop_backing_dev_info and this led to crashes inside locked_inode_to_wb_and_lock_list() called from __mark_inode_dirty(). Fix the problem by initializing noop_backing_dev_info before the filesystems get mounted.
Fixes: 10e14073107d ("writeback: Fix inode->i_io_list not be protected by inode->i_lock error") Reported-and-tested-by: Suzuki K Poulose <suzuki.poulose@arm.com> Reported-and-tested-by: Alexandru Elisei <alexandru.elisei@arm.com> Reported-and-tested-by: Guenter Roeck <linux@roeck-us.net> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jan Kara <jack@suse.cz>
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Revision tags: v5.15.47, v5.15.46, v5.15.45, v5.15.44, v5.15.43, v5.15.42, v5.18, v5.15.41, v5.15.40, v5.15.39, v5.15.38, v5.15.37, v5.15.36, v5.15.35 |
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c97ab271 |
| 19-Apr-2022 |
Christoph Hellwig <hch@lst.de> |
blk-cgroup: remove unneeded includes from <linux/blk-cgroup.h>
Remove all the includes that aren't actually needed from <linux/blk-cgroup.h> and push them to the actual source files where needed.
S
blk-cgroup: remove unneeded includes from <linux/blk-cgroup.h>
Remove all the includes that aren't actually needed from <linux/blk-cgroup.h> and push them to the actual source files where needed.
Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Tejun Heo <tj@kernel.org> Link: https://lore.kernel.org/r/20220420042723.1010598-12-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
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dec223c9 |
| 19-Apr-2022 |
Christoph Hellwig <hch@lst.de> |
blk-cgroup: move struct blkcg to block/blk-cgroup.h
There is no real need to expose the blkcg structure to the whole kernel. Move it to the private header an expose a helper to let the writeback cod
blk-cgroup: move struct blkcg to block/blk-cgroup.h
There is no real need to expose the blkcg structure to the whole kernel. Move it to the private header an expose a helper to let the writeback code access the cgwb_list member.
Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Tejun Heo <tj@kernel.org> Link: https://lore.kernel.org/r/20220420042723.1010598-8-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
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397c9f46 |
| 19-Apr-2022 |
Christoph Hellwig <hch@lst.de> |
blk-cgroup: move blkcg_{pin,unpin}_online out of line
Move these two functions out of line as there is no good reason to inline them. Also switch to passing a cgroup_subsys_state instead of doing t
blk-cgroup: move blkcg_{pin,unpin}_online out of line
Move these two functions out of line as there is no good reason to inline them. Also switch to passing a cgroup_subsys_state instead of doing the conversion in the caller to prepare for making the blkcg structure private to blk-cgroup.
Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Tejun Heo <tj@kernel.org> Link: https://lore.kernel.org/r/20220420042723.1010598-7-hch@lst.de Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Revision tags: v5.15.34, v5.15.33, v5.15.32, v5.15.31 |
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a88f2096 |
| 22-Mar-2022 |
NeilBrown <neilb@suse.de> |
remove congestion tracking framework
This framework is no longer used - so discard it.
Link: https://lkml.kernel.org/r/164549983747.9187.6171768583526866601.stgit@noble.brown Signed-off-by: NeilBro
remove congestion tracking framework
This framework is no longer used - so discard it.
Link: https://lkml.kernel.org/r/164549983747.9187.6171768583526866601.stgit@noble.brown Signed-off-by: NeilBrown <neilb@suse.de> Cc: Anna Schumaker <Anna.Schumaker@Netapp.com> Cc: Chao Yu <chao@kernel.org> Cc: Darrick J. Wong <djwong@kernel.org> Cc: Ilya Dryomov <idryomov@gmail.com> Cc: Jaegeuk Kim <jaegeuk@kernel.org> Cc: Jan Kara <jack@suse.cz> Cc: Jeff Layton <jlayton@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Lars Ellenberg <lars.ellenberg@linbit.com> Cc: Miklos Szeredi <miklos@szeredi.hu> Cc: Paolo Valente <paolo.valente@linaro.org> Cc: Philipp Reisner <philipp.reisner@linbit.com> Cc: Ryusuke Konishi <konishi.ryusuke@gmail.com> Cc: Trond Myklebust <trond.myklebust@hammerspace.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Revision tags: v5.17, v5.15.30, v5.15.29, v5.15.28, v5.15.27, v5.15.26, v5.15.25, v5.15.24, v5.15.23, v5.15.22, v5.15.21, v5.15.20, v5.15.19, v5.15.18, v5.15.17, v5.4.173, v5.15.16, v5.15.15, v5.16, v5.15.10, v5.15.9, v5.15.8 |
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3c376dfa |
| 10-Dec-2021 |
Manjong Lee <mj0123.lee@samsung.com> |
mm: bdi: initialize bdi_min_ratio when bdi is unregistered
Initialize min_ratio if it is set during bdi unregistration. This can prevent problems that may occur a when bdi is removed without resett
mm: bdi: initialize bdi_min_ratio when bdi is unregistered
Initialize min_ratio if it is set during bdi unregistration. This can prevent problems that may occur a when bdi is removed without resetting min_ratio.
For example. 1) insert external sdcard 2) set external sdcard's min_ratio 70 3) remove external sdcard without setting min_ratio 0 4) insert external sdcard 5) set external sdcard's min_ratio 70 << error occur(can't set)
Because when an sdcard is removed, the present bdi_min_ratio value will remain. Currently, the only way to reset bdi_min_ratio is to reboot.
[akpm@linux-foundation.org: tweak comment and coding style]
Link: https://lkml.kernel.org/r/20211021161942.5983-1-mj0123.lee@samsung.com Signed-off-by: Manjong Lee <mj0123.lee@samsung.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Changheun Lee <nanich.lee@samsung.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Christoph Hellwig <hch@infradead.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: <seunghwan.hyun@samsung.com> Cc: <sookwan7.kim@samsung.com> Cc: <yt0928.kim@samsung.com> Cc: <junho89.kim@samsung.com> Cc: <jisoo2146.oh@samsung.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Revision tags: v5.15.7, v5.15.6, v5.15.5, v5.15.4, v5.15.3, v5.15.2, v5.15.1 |
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8cd7c588 |
| 05-Nov-2021 |
Mel Gorman <mgorman@techsingularity.net> |
mm/vmscan: throttle reclaim until some writeback completes if congested
Patch series "Remove dependency on congestion_wait in mm/", v5.
This series that removes all calls to congestion_wait in mm/
mm/vmscan: throttle reclaim until some writeback completes if congested
Patch series "Remove dependency on congestion_wait in mm/", v5.
This series that removes all calls to congestion_wait in mm/ and deletes wait_iff_congested. It's not a clever implementation but congestion_wait has been broken for a long time [1].
Even if congestion throttling worked, it was never a great idea. While excessive dirty/writeback pages at the tail of the LRU is one possibility that reclaim may be slow, there is also the problem of too many pages being isolated and reclaim failing for other reasons (elevated references, too many pages isolated, excessive LRU contention etc).
This series replaces the "congestion" throttling with 3 different types.
- If there are too many dirty/writeback pages, sleep until a timeout or enough pages get cleaned
- If too many pages are isolated, sleep until enough isolated pages are either reclaimed or put back on the LRU
- If no progress is being made, direct reclaim tasks sleep until another task makes progress with acceptable efficiency.
This was initially tested with a mix of workloads that used to trigger corner cases that no longer work. A new test case was created called "stutterp" (pagereclaim-stutterp-noreaders in mmtests) using a freshly created XFS filesystem. Note that it may be necessary to increase the timeout of ssh if executing remotely as ssh itself can get throttled and the connection may timeout.
stutterp varies the number of "worker" processes from 4 up to NR_CPUS*4 to check the impact as the number of direct reclaimers increase. It has four types of worker.
- One "anon latency" worker creates small mappings with mmap() and times how long it takes to fault the mapping reading it 4K at a time
- X file writers which is fio randomly writing X files where the total size of the files add up to the allowed dirty_ratio. fio is allowed to run for a warmup period to allow some file-backed pages to accumulate. The duration of the warmup is based on the best-case linear write speed of the storage.
- Y file readers which is fio randomly reading small files
- Z anon memory hogs which continually map (100-dirty_ratio)% of memory
- Total estimated WSS = (100+dirty_ration) percentage of memory
X+Y+Z+1 == NR_WORKERS varying from 4 up to NR_CPUS*4
The intent is to maximise the total WSS with a mix of file and anon memory where some anonymous memory must be swapped and there is a high likelihood of dirty/writeback pages reaching the end of the LRU.
The test can be configured to have no background readers to stress dirty/writeback pages. The results below are based on having zero readers.
The short summary of the results is that the series works and stalls until some event occurs but the timeouts may need adjustment.
The test results are not broken down by patch as the series should be treated as one block that replaces a broken throttling mechanism with a working one.
Finally, three machines were tested but I'm reporting the worst set of results. The other two machines had much better latencies for example.
First the results of the "anon latency" latency
stutterp 5.15.0-rc1 5.15.0-rc1 vanilla mm-reclaimcongest-v5r4 Amean mmap-4 31.4003 ( 0.00%) 2661.0198 (-8374.52%) Amean mmap-7 38.1641 ( 0.00%) 149.2891 (-291.18%) Amean mmap-12 60.0981 ( 0.00%) 187.8105 (-212.51%) Amean mmap-21 161.2699 ( 0.00%) 213.9107 ( -32.64%) Amean mmap-30 174.5589 ( 0.00%) 377.7548 (-116.41%) Amean mmap-48 8106.8160 ( 0.00%) 1070.5616 ( 86.79%) Stddev mmap-4 41.3455 ( 0.00%) 27573.9676 (-66591.66%) Stddev mmap-7 53.5556 ( 0.00%) 4608.5860 (-8505.23%) Stddev mmap-12 171.3897 ( 0.00%) 5559.4542 (-3143.75%) Stddev mmap-21 1506.6752 ( 0.00%) 5746.2507 (-281.39%) Stddev mmap-30 557.5806 ( 0.00%) 7678.1624 (-1277.05%) Stddev mmap-48 61681.5718 ( 0.00%) 14507.2830 ( 76.48%) Max-90 mmap-4 31.4243 ( 0.00%) 83.1457 (-164.59%) Max-90 mmap-7 41.0410 ( 0.00%) 41.0720 ( -0.08%) Max-90 mmap-12 66.5255 ( 0.00%) 53.9073 ( 18.97%) Max-90 mmap-21 146.7479 ( 0.00%) 105.9540 ( 27.80%) Max-90 mmap-30 193.9513 ( 0.00%) 64.3067 ( 66.84%) Max-90 mmap-48 277.9137 ( 0.00%) 591.0594 (-112.68%) Max mmap-4 1913.8009 ( 0.00%) 299623.9695 (-15555.96%) Max mmap-7 2423.9665 ( 0.00%) 204453.1708 (-8334.65%) Max mmap-12 6845.6573 ( 0.00%) 221090.3366 (-3129.64%) Max mmap-21 56278.6508 ( 0.00%) 213877.3496 (-280.03%) Max mmap-30 19716.2990 ( 0.00%) 216287.6229 (-997.00%) Max mmap-48 477923.9400 ( 0.00%) 245414.8238 ( 48.65%)
For most thread counts, the time to mmap() is unfortunately increased. In earlier versions of the series, this was lower but a large number of throttling events were reaching their timeout increasing the amount of inefficient scanning of the LRU. There is no prioritisation of reclaim tasks making progress based on each tasks rate of page allocation versus progress of reclaim. The variance is also impacted for high worker counts but in all cases, the differences in latency are not statistically significant due to very large maximum outliers. Max-90 shows that 90% of the stalls are comparable but the Max results show the massive outliers which are increased to to stalling.
It is expected that this will be very machine dependant. Due to the test design, reclaim is difficult so allocations stall and there are variances depending on whether THPs can be allocated or not. The amount of memory will affect exactly how bad the corner cases are and how often they trigger. The warmup period calculation is not ideal as it's based on linear writes where as fio is randomly writing multiple files from multiple tasks so the start state of the test is variable. For example, these are the latencies on a single-socket machine that had more memory
Amean mmap-4 42.2287 ( 0.00%) 49.6838 * -17.65%* Amean mmap-7 216.4326 ( 0.00%) 47.4451 * 78.08%* Amean mmap-12 2412.0588 ( 0.00%) 51.7497 ( 97.85%) Amean mmap-21 5546.2548 ( 0.00%) 51.8862 ( 99.06%) Amean mmap-30 1085.3121 ( 0.00%) 72.1004 ( 93.36%)
The overall system CPU usage and elapsed time is as follows
5.15.0-rc3 5.15.0-rc3 vanilla mm-reclaimcongest-v5r4 Duration User 6989.03 983.42 Duration System 7308.12 799.68 Duration Elapsed 2277.67 2092.98
The patches reduce system CPU usage by 89% as the vanilla kernel is rarely stalling.
The high-level /proc/vmstats show
5.15.0-rc1 5.15.0-rc1 vanilla mm-reclaimcongest-v5r2 Ops Direct pages scanned 1056608451.00 503594991.00 Ops Kswapd pages scanned 109795048.00 147289810.00 Ops Kswapd pages reclaimed 63269243.00 31036005.00 Ops Direct pages reclaimed 10803973.00 6328887.00 Ops Kswapd efficiency % 57.62 21.07 Ops Kswapd velocity 48204.98 57572.86 Ops Direct efficiency % 1.02 1.26 Ops Direct velocity 463898.83 196845.97
Kswapd scanned less pages but the detailed pattern is different. The vanilla kernel scans slowly over time where as the patches exhibits burst patterns of scan activity. Direct reclaim scanning is reduced by 52% due to stalling.
The pattern for stealing pages is also slightly different. Both kernels exhibit spikes but the vanilla kernel when reclaiming shows pages being reclaimed over a period of time where as the patches tend to reclaim in spikes. The difference is that vanilla is not throttling and instead scanning constantly finding some pages over time where as the patched kernel throttles and reclaims in spikes.
Ops Percentage direct scans 90.59 77.37
For direct reclaim, vanilla scanned 90.59% of pages where as with the patches, 77.37% were direct reclaim due to throttling
Ops Page writes by reclaim 2613590.00 1687131.00
Page writes from reclaim context are reduced.
Ops Page writes anon 2932752.00 1917048.00
And there is less swapping.
Ops Page reclaim immediate 996248528.00 107664764.00
The number of pages encountered at the tail of the LRU tagged for immediate reclaim but still dirty/writeback is reduced by 89%.
Ops Slabs scanned 164284.00 153608.00
Slab scan activity is similar.
ftrace was used to gather stall activity
Vanilla ------- 1 writeback_wait_iff_congested: usec_timeout=100000 usec_delayed=16000 2 writeback_wait_iff_congested: usec_timeout=100000 usec_delayed=12000 8 writeback_wait_iff_congested: usec_timeout=100000 usec_delayed=8000 29 writeback_wait_iff_congested: usec_timeout=100000 usec_delayed=4000 82394 writeback_wait_iff_congested: usec_timeout=100000 usec_delayed=0
The fast majority of wait_iff_congested calls do not stall at all. What is likely happening is that cond_resched() reschedules the task for a short period when the BDI is not registering congestion (which it never will in this test setup).
1 writeback_congestion_wait: usec_timeout=100000 usec_delayed=120000 2 writeback_congestion_wait: usec_timeout=100000 usec_delayed=132000 4 writeback_congestion_wait: usec_timeout=100000 usec_delayed=112000 380 writeback_congestion_wait: usec_timeout=100000 usec_delayed=108000 778 writeback_congestion_wait: usec_timeout=100000 usec_delayed=104000
congestion_wait if called always exceeds the timeout as there is no trigger to wake it up.
Bottom line: Vanilla will throttle but it's not effective.
Patch series ------------
Kswapd throttle activity was always due to scanning pages tagged for immediate reclaim at the tail of the LRU
1 usec_timeout=100000 usect_delayed=72000 reason=VMSCAN_THROTTLE_WRITEBACK 4 usec_timeout=100000 usect_delayed=20000 reason=VMSCAN_THROTTLE_WRITEBACK 5 usec_timeout=100000 usect_delayed=12000 reason=VMSCAN_THROTTLE_WRITEBACK 6 usec_timeout=100000 usect_delayed=16000 reason=VMSCAN_THROTTLE_WRITEBACK 11 usec_timeout=100000 usect_delayed=100000 reason=VMSCAN_THROTTLE_WRITEBACK 11 usec_timeout=100000 usect_delayed=8000 reason=VMSCAN_THROTTLE_WRITEBACK 94 usec_timeout=100000 usect_delayed=0 reason=VMSCAN_THROTTLE_WRITEBACK 112 usec_timeout=100000 usect_delayed=4000 reason=VMSCAN_THROTTLE_WRITEBACK
The majority of events did not stall or stalled for a short period. Roughly 16% of stalls reached the timeout before expiry. For direct reclaim, the number of times stalled for each reason were
6624 reason=VMSCAN_THROTTLE_ISOLATED 93246 reason=VMSCAN_THROTTLE_NOPROGRESS 96934 reason=VMSCAN_THROTTLE_WRITEBACK
The most common reason to stall was due to excessive pages tagged for immediate reclaim at the tail of the LRU followed by a failure to make forward. A relatively small number were due to too many pages isolated from the LRU by parallel threads
For VMSCAN_THROTTLE_ISOLATED, the breakdown of delays was
9 usec_timeout=20000 usect_delayed=4000 reason=VMSCAN_THROTTLE_ISOLATED 12 usec_timeout=20000 usect_delayed=16000 reason=VMSCAN_THROTTLE_ISOLATED 83 usec_timeout=20000 usect_delayed=20000 reason=VMSCAN_THROTTLE_ISOLATED 6520 usec_timeout=20000 usect_delayed=0 reason=VMSCAN_THROTTLE_ISOLATED
Most did not stall at all. A small number reached the timeout.
For VMSCAN_THROTTLE_NOPROGRESS, the breakdown of stalls were all over the map
1 usec_timeout=500000 usect_delayed=324000 reason=VMSCAN_THROTTLE_NOPROGRESS 1 usec_timeout=500000 usect_delayed=332000 reason=VMSCAN_THROTTLE_NOPROGRESS 1 usec_timeout=500000 usect_delayed=348000 reason=VMSCAN_THROTTLE_NOPROGRESS 1 usec_timeout=500000 usect_delayed=360000 reason=VMSCAN_THROTTLE_NOPROGRESS 2 usec_timeout=500000 usect_delayed=228000 reason=VMSCAN_THROTTLE_NOPROGRESS 2 usec_timeout=500000 usect_delayed=260000 reason=VMSCAN_THROTTLE_NOPROGRESS 2 usec_timeout=500000 usect_delayed=340000 reason=VMSCAN_THROTTLE_NOPROGRESS 2 usec_timeout=500000 usect_delayed=364000 reason=VMSCAN_THROTTLE_NOPROGRESS 2 usec_timeout=500000 usect_delayed=372000 reason=VMSCAN_THROTTLE_NOPROGRESS 2 usec_timeout=500000 usect_delayed=428000 reason=VMSCAN_THROTTLE_NOPROGRESS 2 usec_timeout=500000 usect_delayed=460000 reason=VMSCAN_THROTTLE_NOPROGRESS 2 usec_timeout=500000 usect_delayed=464000 reason=VMSCAN_THROTTLE_NOPROGRESS 3 usec_timeout=500000 usect_delayed=244000 reason=VMSCAN_THROTTLE_NOPROGRESS 3 usec_timeout=500000 usect_delayed=252000 reason=VMSCAN_THROTTLE_NOPROGRESS 3 usec_timeout=500000 usect_delayed=272000 reason=VMSCAN_THROTTLE_NOPROGRESS 4 usec_timeout=500000 usect_delayed=188000 reason=VMSCAN_THROTTLE_NOPROGRESS 4 usec_timeout=500000 usect_delayed=268000 reason=VMSCAN_THROTTLE_NOPROGRESS 4 usec_timeout=500000 usect_delayed=328000 reason=VMSCAN_THROTTLE_NOPROGRESS 4 usec_timeout=500000 usect_delayed=380000 reason=VMSCAN_THROTTLE_NOPROGRESS 4 usec_timeout=500000 usect_delayed=392000 reason=VMSCAN_THROTTLE_NOPROGRESS 4 usec_timeout=500000 usect_delayed=432000 reason=VMSCAN_THROTTLE_NOPROGRESS 5 usec_timeout=500000 usect_delayed=204000 reason=VMSCAN_THROTTLE_NOPROGRESS 5 usec_timeout=500000 usect_delayed=220000 reason=VMSCAN_THROTTLE_NOPROGRESS 5 usec_timeout=500000 usect_delayed=412000 reason=VMSCAN_THROTTLE_NOPROGRESS 5 usec_timeout=500000 usect_delayed=436000 reason=VMSCAN_THROTTLE_NOPROGRESS 6 usec_timeout=500000 usect_delayed=488000 reason=VMSCAN_THROTTLE_NOPROGRESS 7 usec_timeout=500000 usect_delayed=212000 reason=VMSCAN_THROTTLE_NOPROGRESS 7 usec_timeout=500000 usect_delayed=300000 reason=VMSCAN_THROTTLE_NOPROGRESS 7 usec_timeout=500000 usect_delayed=316000 reason=VMSCAN_THROTTLE_NOPROGRESS 7 usec_timeout=500000 usect_delayed=472000 reason=VMSCAN_THROTTLE_NOPROGRESS 8 usec_timeout=500000 usect_delayed=248000 reason=VMSCAN_THROTTLE_NOPROGRESS 8 usec_timeout=500000 usect_delayed=356000 reason=VMSCAN_THROTTLE_NOPROGRESS 8 usec_timeout=500000 usect_delayed=456000 reason=VMSCAN_THROTTLE_NOPROGRESS 9 usec_timeout=500000 usect_delayed=124000 reason=VMSCAN_THROTTLE_NOPROGRESS 9 usec_timeout=500000 usect_delayed=376000 reason=VMSCAN_THROTTLE_NOPROGRESS 9 usec_timeout=500000 usect_delayed=484000 reason=VMSCAN_THROTTLE_NOPROGRESS 10 usec_timeout=500000 usect_delayed=172000 reason=VMSCAN_THROTTLE_NOPROGRESS 10 usec_timeout=500000 usect_delayed=420000 reason=VMSCAN_THROTTLE_NOPROGRESS 10 usec_timeout=500000 usect_delayed=452000 reason=VMSCAN_THROTTLE_NOPROGRESS 11 usec_timeout=500000 usect_delayed=256000 reason=VMSCAN_THROTTLE_NOPROGRESS 12 usec_timeout=500000 usect_delayed=112000 reason=VMSCAN_THROTTLE_NOPROGRESS 12 usec_timeout=500000 usect_delayed=116000 reason=VMSCAN_THROTTLE_NOPROGRESS 12 usec_timeout=500000 usect_delayed=144000 reason=VMSCAN_THROTTLE_NOPROGRESS 12 usec_timeout=500000 usect_delayed=152000 reason=VMSCAN_THROTTLE_NOPROGRESS 12 usec_timeout=500000 usect_delayed=264000 reason=VMSCAN_THROTTLE_NOPROGRESS 12 usec_timeout=500000 usect_delayed=384000 reason=VMSCAN_THROTTLE_NOPROGRESS 12 usec_timeout=500000 usect_delayed=424000 reason=VMSCAN_THROTTLE_NOPROGRESS 12 usec_timeout=500000 usect_delayed=492000 reason=VMSCAN_THROTTLE_NOPROGRESS 13 usec_timeout=500000 usect_delayed=184000 reason=VMSCAN_THROTTLE_NOPROGRESS 13 usec_timeout=500000 usect_delayed=444000 reason=VMSCAN_THROTTLE_NOPROGRESS 14 usec_timeout=500000 usect_delayed=308000 reason=VMSCAN_THROTTLE_NOPROGRESS 14 usec_timeout=500000 usect_delayed=440000 reason=VMSCAN_THROTTLE_NOPROGRESS 14 usec_timeout=500000 usect_delayed=476000 reason=VMSCAN_THROTTLE_NOPROGRESS 16 usec_timeout=500000 usect_delayed=140000 reason=VMSCAN_THROTTLE_NOPROGRESS 17 usec_timeout=500000 usect_delayed=232000 reason=VMSCAN_THROTTLE_NOPROGRESS 17 usec_timeout=500000 usect_delayed=240000 reason=VMSCAN_THROTTLE_NOPROGRESS 17 usec_timeout=500000 usect_delayed=280000 reason=VMSCAN_THROTTLE_NOPROGRESS 18 usec_timeout=500000 usect_delayed=404000 reason=VMSCAN_THROTTLE_NOPROGRESS 20 usec_timeout=500000 usect_delayed=148000 reason=VMSCAN_THROTTLE_NOPROGRESS 20 usec_timeout=500000 usect_delayed=216000 reason=VMSCAN_THROTTLE_NOPROGRESS 20 usec_timeout=500000 usect_delayed=468000 reason=VMSCAN_THROTTLE_NOPROGRESS 21 usec_timeout=500000 usect_delayed=448000 reason=VMSCAN_THROTTLE_NOPROGRESS 23 usec_timeout=500000 usect_delayed=168000 reason=VMSCAN_THROTTLE_NOPROGRESS 23 usec_timeout=500000 usect_delayed=296000 reason=VMSCAN_THROTTLE_NOPROGRESS 25 usec_timeout=500000 usect_delayed=132000 reason=VMSCAN_THROTTLE_NOPROGRESS 25 usec_timeout=500000 usect_delayed=352000 reason=VMSCAN_THROTTLE_NOPROGRESS 26 usec_timeout=500000 usect_delayed=180000 reason=VMSCAN_THROTTLE_NOPROGRESS 27 usec_timeout=500000 usect_delayed=284000 reason=VMSCAN_THROTTLE_NOPROGRESS 28 usec_timeout=500000 usect_delayed=164000 reason=VMSCAN_THROTTLE_NOPROGRESS 29 usec_timeout=500000 usect_delayed=136000 reason=VMSCAN_THROTTLE_NOPROGRESS 30 usec_timeout=500000 usect_delayed=200000 reason=VMSCAN_THROTTLE_NOPROGRESS 30 usec_timeout=500000 usect_delayed=400000 reason=VMSCAN_THROTTLE_NOPROGRESS 31 usec_timeout=500000 usect_delayed=196000 reason=VMSCAN_THROTTLE_NOPROGRESS 32 usec_timeout=500000 usect_delayed=156000 reason=VMSCAN_THROTTLE_NOPROGRESS 33 usec_timeout=500000 usect_delayed=224000 reason=VMSCAN_THROTTLE_NOPROGRESS 35 usec_timeout=500000 usect_delayed=128000 reason=VMSCAN_THROTTLE_NOPROGRESS 35 usec_timeout=500000 usect_delayed=176000 reason=VMSCAN_THROTTLE_NOPROGRESS 36 usec_timeout=500000 usect_delayed=368000 reason=VMSCAN_THROTTLE_NOPROGRESS 36 usec_timeout=500000 usect_delayed=496000 reason=VMSCAN_THROTTLE_NOPROGRESS 37 usec_timeout=500000 usect_delayed=312000 reason=VMSCAN_THROTTLE_NOPROGRESS 38 usec_timeout=500000 usect_delayed=304000 reason=VMSCAN_THROTTLE_NOPROGRESS 40 usec_timeout=500000 usect_delayed=288000 reason=VMSCAN_THROTTLE_NOPROGRESS 43 usec_timeout=500000 usect_delayed=408000 reason=VMSCAN_THROTTLE_NOPROGRESS 55 usec_timeout=500000 usect_delayed=416000 reason=VMSCAN_THROTTLE_NOPROGRESS 56 usec_timeout=500000 usect_delayed=76000 reason=VMSCAN_THROTTLE_NOPROGRESS 58 usec_timeout=500000 usect_delayed=120000 reason=VMSCAN_THROTTLE_NOPROGRESS 59 usec_timeout=500000 usect_delayed=208000 reason=VMSCAN_THROTTLE_NOPROGRESS 61 usec_timeout=500000 usect_delayed=68000 reason=VMSCAN_THROTTLE_NOPROGRESS 71 usec_timeout=500000 usect_delayed=192000 reason=VMSCAN_THROTTLE_NOPROGRESS 71 usec_timeout=500000 usect_delayed=480000 reason=VMSCAN_THROTTLE_NOPROGRESS 79 usec_timeout=500000 usect_delayed=60000 reason=VMSCAN_THROTTLE_NOPROGRESS 82 usec_timeout=500000 usect_delayed=320000 reason=VMSCAN_THROTTLE_NOPROGRESS 82 usec_timeout=500000 usect_delayed=92000 reason=VMSCAN_THROTTLE_NOPROGRESS 85 usec_timeout=500000 usect_delayed=64000 reason=VMSCAN_THROTTLE_NOPROGRESS 85 usec_timeout=500000 usect_delayed=80000 reason=VMSCAN_THROTTLE_NOPROGRESS 88 usec_timeout=500000 usect_delayed=84000 reason=VMSCAN_THROTTLE_NOPROGRESS 90 usec_timeout=500000 usect_delayed=160000 reason=VMSCAN_THROTTLE_NOPROGRESS 90 usec_timeout=500000 usect_delayed=292000 reason=VMSCAN_THROTTLE_NOPROGRESS 94 usec_timeout=500000 usect_delayed=56000 reason=VMSCAN_THROTTLE_NOPROGRESS 118 usec_timeout=500000 usect_delayed=88000 reason=VMSCAN_THROTTLE_NOPROGRESS 119 usec_timeout=500000 usect_delayed=72000 reason=VMSCAN_THROTTLE_NOPROGRESS 126 usec_timeout=500000 usect_delayed=108000 reason=VMSCAN_THROTTLE_NOPROGRESS 146 usec_timeout=500000 usect_delayed=52000 reason=VMSCAN_THROTTLE_NOPROGRESS 148 usec_timeout=500000 usect_delayed=36000 reason=VMSCAN_THROTTLE_NOPROGRESS 148 usec_timeout=500000 usect_delayed=48000 reason=VMSCAN_THROTTLE_NOPROGRESS 159 usec_timeout=500000 usect_delayed=28000 reason=VMSCAN_THROTTLE_NOPROGRESS 178 usec_timeout=500000 usect_delayed=44000 reason=VMSCAN_THROTTLE_NOPROGRESS 183 usec_timeout=500000 usect_delayed=40000 reason=VMSCAN_THROTTLE_NOPROGRESS 237 usec_timeout=500000 usect_delayed=100000 reason=VMSCAN_THROTTLE_NOPROGRESS 266 usec_timeout=500000 usect_delayed=32000 reason=VMSCAN_THROTTLE_NOPROGRESS 313 usec_timeout=500000 usect_delayed=24000 reason=VMSCAN_THROTTLE_NOPROGRESS 347 usec_timeout=500000 usect_delayed=96000 reason=VMSCAN_THROTTLE_NOPROGRESS 470 usec_timeout=500000 usect_delayed=20000 reason=VMSCAN_THROTTLE_NOPROGRESS 559 usec_timeout=500000 usect_delayed=16000 reason=VMSCAN_THROTTLE_NOPROGRESS 964 usec_timeout=500000 usect_delayed=12000 reason=VMSCAN_THROTTLE_NOPROGRESS 2001 usec_timeout=500000 usect_delayed=104000 reason=VMSCAN_THROTTLE_NOPROGRESS 2447 usec_timeout=500000 usect_delayed=8000 reason=VMSCAN_THROTTLE_NOPROGRESS 7888 usec_timeout=500000 usect_delayed=4000 reason=VMSCAN_THROTTLE_NOPROGRESS 22727 usec_timeout=500000 usect_delayed=0 reason=VMSCAN_THROTTLE_NOPROGRESS 51305 usec_timeout=500000 usect_delayed=500000 reason=VMSCAN_THROTTLE_NOPROGRESS
The full timeout is often hit but a large number also do not stall at all. The remainder slept a little allowing other reclaim tasks to make progress.
While this timeout could be further increased, it could also negatively impact worst-case behaviour when there is no prioritisation of what task should make progress.
For VMSCAN_THROTTLE_WRITEBACK, the breakdown was
1 usec_timeout=100000 usect_delayed=44000 reason=VMSCAN_THROTTLE_WRITEBACK 2 usec_timeout=100000 usect_delayed=76000 reason=VMSCAN_THROTTLE_WRITEBACK 3 usec_timeout=100000 usect_delayed=80000 reason=VMSCAN_THROTTLE_WRITEBACK 5 usec_timeout=100000 usect_delayed=48000 reason=VMSCAN_THROTTLE_WRITEBACK 5 usec_timeout=100000 usect_delayed=84000 reason=VMSCAN_THROTTLE_WRITEBACK 6 usec_timeout=100000 usect_delayed=72000 reason=VMSCAN_THROTTLE_WRITEBACK 7 usec_timeout=100000 usect_delayed=88000 reason=VMSCAN_THROTTLE_WRITEBACK 11 usec_timeout=100000 usect_delayed=56000 reason=VMSCAN_THROTTLE_WRITEBACK 12 usec_timeout=100000 usect_delayed=64000 reason=VMSCAN_THROTTLE_WRITEBACK 16 usec_timeout=100000 usect_delayed=92000 reason=VMSCAN_THROTTLE_WRITEBACK 24 usec_timeout=100000 usect_delayed=68000 reason=VMSCAN_THROTTLE_WRITEBACK 28 usec_timeout=100000 usect_delayed=32000 reason=VMSCAN_THROTTLE_WRITEBACK 30 usec_timeout=100000 usect_delayed=60000 reason=VMSCAN_THROTTLE_WRITEBACK 30 usec_timeout=100000 usect_delayed=96000 reason=VMSCAN_THROTTLE_WRITEBACK 32 usec_timeout=100000 usect_delayed=52000 reason=VMSCAN_THROTTLE_WRITEBACK 42 usec_timeout=100000 usect_delayed=40000 reason=VMSCAN_THROTTLE_WRITEBACK 77 usec_timeout=100000 usect_delayed=28000 reason=VMSCAN_THROTTLE_WRITEBACK 99 usec_timeout=100000 usect_delayed=36000 reason=VMSCAN_THROTTLE_WRITEBACK 137 usec_timeout=100000 usect_delayed=24000 reason=VMSCAN_THROTTLE_WRITEBACK 190 usec_timeout=100000 usect_delayed=20000 reason=VMSCAN_THROTTLE_WRITEBACK 339 usec_timeout=100000 usect_delayed=16000 reason=VMSCAN_THROTTLE_WRITEBACK 518 usec_timeout=100000 usect_delayed=12000 reason=VMSCAN_THROTTLE_WRITEBACK 852 usec_timeout=100000 usect_delayed=8000 reason=VMSCAN_THROTTLE_WRITEBACK 3359 usec_timeout=100000 usect_delayed=4000 reason=VMSCAN_THROTTLE_WRITEBACK 7147 usec_timeout=100000 usect_delayed=0 reason=VMSCAN_THROTTLE_WRITEBACK 83962 usec_timeout=100000 usect_delayed=100000 reason=VMSCAN_THROTTLE_WRITEBACK
The majority hit the timeout in direct reclaim context although a sizable number did not stall at all. This is very different to kswapd where only a tiny percentage of stalls due to writeback reached the timeout.
Bottom line, the throttling appears to work and the wakeup events may limit worst case stalls. There might be some grounds for adjusting timeouts but it's likely futile as the worst-case scenarios depend on the workload, memory size and the speed of the storage. A better approach to improve the series further would be to prioritise tasks based on their rate of allocation with the caveat that it may be very expensive to track.
This patch (of 5):
Page reclaim throttles on wait_iff_congested under the following conditions:
- kswapd is encountering pages under writeback and marked for immediate reclaim implying that pages are cycling through the LRU faster than pages can be cleaned.
- Direct reclaim will stall if all dirty pages are backed by congested inodes.
wait_iff_congested is almost completely broken with few exceptions. This patch adds a new node-based workqueue and tracks the number of throttled tasks and pages written back since throttling started. If enough pages belonging to the node are written back then the throttled tasks will wake early. If not, the throttled tasks sleeps until the timeout expires.
[neilb@suse.de: Uninterruptible sleep and simpler wakeups] [hdanton@sina.com: Avoid race when reclaim starts] [vbabka@suse.cz: vmstat irq-safe api, clarifications]
Link: https://lore.kernel.org/linux-mm/45d8b7a6-8548-65f5-cccf-9f451d4ae3d4@kernel.dk/ [1] Link: https://lkml.kernel.org/r/20211022144651.19914-1-mgorman@techsingularity.net Link: https://lkml.kernel.org/r/20211022144651.19914-2-mgorman@techsingularity.net Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: NeilBrown <neilb@suse.de> Cc: "Theodore Ts'o" <tytso@mit.edu> Cc: Andreas Dilger <adilger.kernel@dilger.ca> Cc: "Darrick J . Wong" <djwong@kernel.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Rik van Riel <riel@surriel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Jonathan Corbet <corbet@lwn.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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efee1713 |
| 05-Nov-2021 |
Christoph Hellwig <hch@lst.de> |
mm: simplify bdi refcounting
Move grabbing and releasing the bdi refcount out of the common wb_init/wb_exit helpers into code that is only used for the non-default memcg driven bdi_writeback structu
mm: simplify bdi refcounting
Move grabbing and releasing the bdi refcount out of the common wb_init/wb_exit helpers into code that is only used for the non-default memcg driven bdi_writeback structures.
[hch@lst.de: add comment] Link: https://lkml.kernel.org/r/20211027074207.GA12793@lst.de [akpm@linux-foundation.org: fix typo]
Link: https://lkml.kernel.org/r/20211021124441.668816-6-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Miquel Raynal <miquel.raynal@bootlin.com> Cc: Richard Weinberger <richard@nod.at> Cc: Vignesh Raghavendra <vigneshr@ti.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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702f2d1e |
| 05-Nov-2021 |
Christoph Hellwig <hch@lst.de> |
mm: don't automatically unregister bdis
All BDI users now unregister explicitly.
Link: https://lkml.kernel.org/r/20211021124441.668816-5-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Rev
mm: don't automatically unregister bdis
All BDI users now unregister explicitly.
Link: https://lkml.kernel.org/r/20211021124441.668816-5-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Miquel Raynal <miquel.raynal@bootlin.com> Cc: Richard Weinberger <richard@nod.at> Cc: Vignesh Raghavendra <vigneshr@ti.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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c6fd3ac0 |
| 05-Nov-2021 |
Christoph Hellwig <hch@lst.de> |
mm: export bdi_unregister
Patch series "simplify bdi unregistation".
This series simplifies the BDI code to get rid of the magic auto-unregister feature that hid a recent block layer refcounting bu
mm: export bdi_unregister
Patch series "simplify bdi unregistation".
This series simplifies the BDI code to get rid of the magic auto-unregister feature that hid a recent block layer refcounting bug.
This patch (of 5):
To wind down the magic auto-unregister semantics we'll need to push this into modular code.
Link: https://lkml.kernel.org/r/20211021124441.668816-1-hch@lst.de Link: https://lkml.kernel.org/r/20211021124441.668816-2-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jan Kara <jack@suse.cz> Cc: Miquel Raynal <miquel.raynal@bootlin.com> Cc: Richard Weinberger <richard@nod.at> Cc: Vignesh Raghavendra <vigneshr@ti.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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