ll_rw_block() is not safe for the sync read path because it cannot
guarantee that submitting read IO if the buffer has been locked. We
could get false positive EIO after wait_on_buffer() if the buffer has
been locked by others. So stop using ll_rw_block(). We also switch to
new bh_readahead_batch() helper for the buffer array readahead path.
Link: https://lkml.kernel.org/r/20220901133505.2510834-11-yi.zhang@huawei.com
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
ll_rw_block() is not safe for the sync read/write path because it cannot
guarantee that submitting read/write IO if the buffer has been locked.
We could get false positive EIO after wait_on_buffer() in read path if
the buffer has been locked by others. So stop using ll_rw_block() in
reiserfs. We also switch to new bh_readahead_batch() helper for the
buffer array readahead path.
Link: https://lkml.kernel.org/r/20220901133505.2510834-10-yi.zhang@huawei.com
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
ll_rw_block() is not safe for the sync read path because it cannot
guarantee that submitting read IO if the buffer has been locked. We
could get false positive EIO after wait_on_buffer() if the buffer has
been locked by others. So stop using ll_rw_block() in
journal_get_superblock(). We also switch to new bh_readahead_batch()
for the buffer array readahead path.
Link: https://lkml.kernel.org/r/20220901133505.2510834-7-yi.zhang@huawei.com
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
ll_rw_block() is not safe for the sync read path because it cannot
guarantee that submitting read IO if the buffer has been locked. We
could get false positive EIO return from zisofs_uncompress_block() if
he buffer has been locked by others. So stop using ll_rw_block(),
switch to sync helper instead.
Link: https://lkml.kernel.org/r/20220901133505.2510834-6-yi.zhang@huawei.com
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Current ll_rw_block() helper is fragile because it assumes that locked
buffer means it's under IO which is submitted by some other who holds
the lock, it skip buffer if it failed to get the lock, so it's only
safe on the readahead path. Unfortunately, now that most filesystems
still use this helper mistakenly on the sync metadata read path. There
is no guarantee that the one who holds the buffer lock always submit IO
(e.g. buffer_migrate_folio_norefs() after commit 88dbcbb3a4 ("blkdev:
avoid migration stalls for blkdev pages"), it could lead to false
positive -EIO when submitting reading IO.
This patch add some friendly buffer read helpers to prepare replacing
ll_rw_block() and similar calls. We can only call bh_readahead_[]
helpers for the readahead paths.
Link: https://lkml.kernel.org/r/20220901133505.2510834-3-yi.zhang@huawei.com
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
find_vmap_lowest_match() is now able to handle different roots. With
DEBUG_AUGMENT_LOWEST_MATCH_CHECK enabled as:
: --- a/mm/vmalloc.c
: +++ b/mm/vmalloc.c
: @@ -713,7 +713,7 @@ EXPORT_SYMBOL(vmalloc_to_pfn);
: /*** Global kva allocator ***/
:
: -#define DEBUG_AUGMENT_LOWEST_MATCH_CHECK 0
: +#define DEBUG_AUGMENT_LOWEST_MATCH_CHECK 1
compilation failed as:
mm/vmalloc.c: In function 'find_vmap_lowest_match_check':
mm/vmalloc.c:1328:32: warning: passing argument 1 of 'find_vmap_lowest_match' makes pointer from integer without a cast [-Wint-conversion]
1328 | va_1 = find_vmap_lowest_match(size, align, vstart, false);
| ^~~~
| |
| long unsigned int
mm/vmalloc.c:1236:40: note: expected 'struct rb_root *' but argument is of type 'long unsigned int'
1236 | find_vmap_lowest_match(struct rb_root *root, unsigned long size,
| ~~~~~~~~~~~~~~~~^~~~
mm/vmalloc.c:1328:9: error: too few arguments to function 'find_vmap_lowest_match'
1328 | va_1 = find_vmap_lowest_match(size, align, vstart, false);
| ^~~~~~~~~~~~~~~~~~~~~~
mm/vmalloc.c:1236:1: note: declared here
1236 | find_vmap_lowest_match(struct rb_root *root, unsigned long size,
| ^~~~~~~~~~~~~~~~~~~~~~
Extend find_vmap_lowest_match_check() and find_vmap_lowest_linear_match()
with extra arguments to fix this.
Link: https://lkml.kernel.org/r/20220906060548.1127396-1-song@kernel.org
Link: https://lkml.kernel.org/r/20220831052734.3423079-1-song@kernel.org
Fixes: f9863be493 ("mm/vmalloc: extend __alloc_vmap_area() with extra arguments")
Signed-off-by: Song Liu <song@kernel.org>
Reviewed-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The damon regions that belong to the same damon target have the same
'struct mm_struct *mm', so it's unnecessary to compare the mm and last_mm
objects among the damon regions in one damon target when checking
accesses. But the check is necessary when the target changed in
'__damon_va_check_accesses()', so we can simplify the whole operation by
using the bool 'same_target' to indicate whether the target changed.
Link: https://lkml.kernel.org/r/1661590971-20893-3-git-send-email-kaixuxia@tencent.com
Signed-off-by: Kaixu Xia <kaixuxia@tencent.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
kswapd_run/stop() will set pgdat->kswapd to NULL, which could race with
kswapd_is_running() in kcompactd(),
kswapd_run/stop() kcompactd()
kswapd_is_running()
pgdat->kswapd // error or nomal ptr
verify pgdat->kswapd
// load non-NULL
pgdat->kswapd
pgdat->kswapd = NULL
task_is_running(pgdat->kswapd)
// Null pointer derefence
KASAN reports the null-ptr-deref shown below,
vmscan: Failed to start kswapd on node 0
...
BUG: KASAN: null-ptr-deref in kcompactd+0x440/0x504
Read of size 8 at addr 0000000000000024 by task kcompactd0/37
CPU: 0 PID: 37 Comm: kcompactd0 Kdump: loaded Tainted: G OE 5.10.60 #1
Hardware name: QEMU KVM Virtual Machine, BIOS 0.0.0 02/06/2015
Call trace:
dump_backtrace+0x0/0x394
show_stack+0x34/0x4c
dump_stack+0x158/0x1e4
__kasan_report+0x138/0x140
kasan_report+0x44/0xdc
__asan_load8+0x94/0xd0
kcompactd+0x440/0x504
kthread+0x1a4/0x1f0
ret_from_fork+0x10/0x18
At present kswapd/kcompactd_run() and kswapd/kcompactd_stop() are protected
by mem_hotplug_begin/done(), but without kcompactd(). There is no need to
involve memory hotplug lock in kcompactd(), so let's add a new mutex to
protect pgdat->kswapd accesses.
Also, because the kcompactd task will check the state of kswapd task, it's
better to call kcompactd_stop() before kswapd_stop() to reduce lock
conflicts.
[akpm@linux-foundation.org: add comments]
Link: https://lkml.kernel.org/r/20220827111959.186838-1-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Convert to use folios throughout. This is in preparation for the removal
for find_get_pages_contig(). Now also supports large folios.
The initial version of this function set the page_address to be returned
after finishing all the checks. Since folio_batches have a maximum of 15
folios, the function had to be modified to support getting and checking up
to lpages, 15 pages at a time while still returning the initial page
address. Now the function sets ret as soon as the first batch arrives,
and updates it only if a check fails.
The physical adjacency check utilizes the page frame numbers. The page
frame number of each folio must be nr_pages away from the first folio.
Link: https://lkml.kernel.org/r/20220824004023.77310-7-vishal.moola@gmail.com
Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Chris Mason <clm@fb.com>
Cc: David Sterba <dsterba@suse.com>
Cc: David Sterba <dsterb@suse.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
In commit 2f1ee0913c ("Revert "mm: use early_pfn_to_nid in
page_ext_init""), we call page_ext_init() after page_alloc_init_late() to
avoid some panic problem. It seems that we cannot track early page
allocations in current kernel even if page structure has been initialized
early.
This patch introduces a new boot parameter 'early_page_ext' to resolve
this problem. If we pass it to the kernel, page_ext_init() will be moved
up and the feature 'deferred initialization of struct pages' will be
disabled to initialize the page allocator early and prevent the panic
problem above. It can help us to catch early page allocations. This is
useful especially when we find that the free memory value is not the same
right after different kernel booting.
[akpm@linux-foundation.org: fix section issue by removing __meminitdata]
Link: https://lkml.kernel.org/r/20220825102714.669-1-lizhe.67@bytedance.com
Signed-off-by: Li Zhe <lizhe.67@bytedance.com>
Suggested-by: Michal Hocko <mhocko@suse.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Jason A. Donenfeld <Jason@zx2c4.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kees Cook <keescook@chromium.org>
Cc: Mark-PK Tsai <mark-pk.tsai@mediatek.com>
Cc: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
When pud-sized hugepages were introduced for s390, the generic version of
follow_huge_pud() was using pte_page() instead of pud_page(). This would
be wrong for s390, see also commit 9753412701 ("mm/hugetlb: use
pmd_page() in follow_huge_pmd()"). Therefore, and probably because not
all archs were supporting pud_page() at that time, a private version of
follow_huge_pud() was added for s390, correctly using pud_page().
Since commit 3a194f3f8a ("mm/hugetlb: make pud_huge() and
follow_huge_pud() aware of non-present pud entry"), the generic version of
follow_huge_pud() is now also using pud_page(), and in general behaves
similar to follow_huge_pmd().
Therefore we can now switch to the generic version and get rid of the
s390-specific follow_huge_pud().
Link: https://lkml.kernel.org/r/20220818135717.609eef8a@thinkpad
Signed-off-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Haiyue Wang <haiyue.wang@intel.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
For several years, MEMCG_CHARGE_BATCH was kept at 32 but with bigger
machines and the network intensive workloads requiring througput in Gbps,
32 is too small and makes the memcg charging path a bottleneck. For now,
increase it to 64 for easy acceptance to 6.0. We will need to revisit
this in future for ever increasing demand of higher performance.
Please note that the memcg charge path drain the per-cpu memcg charge
stock, so there should not be any oom behavior change. Though it does
have impact on rstat flushing and high limit reclaim backoff.
To evaluate the impact of this optimization, on a 72 CPUs machine, we
ran the following workload in a three level of cgroup hierarchy.
$ netserver -6
# 36 instances of netperf with following params
$ netperf -6 -H ::1 -l 60 -t TCP_SENDFILE -- -m 10K
Results (average throughput of netperf):
Without (6.0-rc1) 10482.7 Mbps
With patch 17064.7 Mbps (62.7% improvement)
With the patch, the throughput improved by 62.7%.
Link: https://lkml.kernel.org/r/20220825000506.239406-4-shakeelb@google.com
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Reported-by: kernel test robot <oliver.sang@intel.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Reviewed-by: Feng Tang <feng.tang@intel.com>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Acked-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: "Michal Koutný" <mkoutny@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
With memcg v2 enabled, memcg->memory.usage is a very hot member for the
workloads doing memcg charging on multiple CPUs concurrently.
Particularly the network intensive workloads. In addition, there is a
false cache sharing between memory.usage and memory.high on the charge
path. This patch moves the usage into a separate cacheline and move all
the read most fields into separate cacheline.
To evaluate the impact of this optimization, on a 72 CPUs machine, we ran
the following workload in a three level of cgroup hierarchy.
$ netserver -6
# 36 instances of netperf with following params
$ netperf -6 -H ::1 -l 60 -t TCP_SENDFILE -- -m 10K
Results (average throughput of netperf):
Without (6.0-rc1) 10482.7 Mbps
With patch 12413.7 Mbps (18.4% improvement)
With the patch, the throughput improved by 18.4%.
One side-effect of this patch is the increase in the size of struct
mem_cgroup. For example with this patch on 64 bit build, the size of
struct mem_cgroup increased from 4032 bytes to 4416 bytes. However for
the performance improvement, this additional size is worth it. In
addition there are opportunities to reduce the size of struct mem_cgroup
like deprecation of kmem and tcpmem page counters and better packing.
Link: https://lkml.kernel.org/r/20220825000506.239406-3-shakeelb@google.com
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Reported-by: kernel test robot <oliver.sang@intel.com>
Reviewed-by: Feng Tang <feng.tang@intel.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: "Michal Koutný" <mkoutny@suse.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "memcg: optimize charge codepath", v2.
Recently Linux networking stack has moved from a very old per socket
pre-charge caching to per-cpu caching to avoid pre-charge fragmentation
and unwarranted OOMs. One impact of this change is that for network
traffic workloads, memcg charging codepath can become a bottleneck. The
kernel test robot has also reported this regression[1]. This patch series
tries to improve the memcg charging for such workloads.
This patch series implement three optimizations:
(A) Reduce atomic ops in page counter update path.
(B) Change layout of struct page_counter to eliminate false sharing
between usage and high.
(C) Increase the memcg charge batch to 64.
To evaluate the impact of these optimizations, on a 72 CPUs machine, we
ran the following workload in root memcg and then compared with scenario
where the workload is run in a three level of cgroup hierarchy with top
level having min and low setup appropriately.
$ netserver -6
# 36 instances of netperf with following params
$ netperf -6 -H ::1 -l 60 -t TCP_SENDFILE -- -m 10K
Results (average throughput of netperf):
1. root memcg 21694.8 Mbps
2. 6.0-rc1 10482.7 Mbps (-51.6%)
3. 6.0-rc1 + (A) 14542.5 Mbps (-32.9%)
4. 6.0-rc1 + (B) 12413.7 Mbps (-42.7%)
5. 6.0-rc1 + (C) 17063.7 Mbps (-21.3%)
6. 6.0-rc1 + (A+B+C) 20120.3 Mbps (-7.2%)
With all three optimizations, the memcg overhead of this workload has
been reduced from 51.6% to just 7.2%.
[1] https://lore.kernel.org/linux-mm/20220619150456.GB34471@xsang-OptiPlex-9020/
This patch (of 3):
For cgroups using low or min protections, the function
propagate_protected_usage() was doing an atomic xchg() operation
irrespectively. We can optimize out this atomic operation for one
specific scenario where the workload is using the protection (i.e. min >
0) and the usage is above the protection (i.e. usage > min).
This scenario is actually very common where the users want a part of their
workload to be protected against the external reclaim. Though this
optimization does introduce a race when the usage is around the protection
and concurrent charges and uncharged trip it over or under the protection.
In such cases, we might see lower effective protection but the subsequent
charge/uncharge will correct it.
To evaluate the impact of this optimization, on a 72 CPUs machine, we ran
the following workload in a three level of cgroup hierarchy with top level
having min and low setup appropriately to see if this optimization is
effective for the mentioned case.
$ netserver -6
# 36 instances of netperf with following params
$ netperf -6 -H ::1 -l 60 -t TCP_SENDFILE -- -m 10K
Results (average throughput of netperf):
Without (6.0-rc1) 10482.7 Mbps
With patch 14542.5 Mbps (38.7% improvement)
With the patch, the throughput improved by 38.7%
Link: https://lkml.kernel.org/r/20220825000506.239406-1-shakeelb@google.com
Link: https://lkml.kernel.org/r/20220825000506.239406-2-shakeelb@google.com
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Reported-by: kernel test robot <oliver.sang@intel.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Reviewed-by: Feng Tang <feng.tang@intel.com>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: "Michal Koutný" <mkoutny@suse.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Oliver Sang <oliver.sang@intel.com>
Cc: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
In page_counter_set_max, we want to make sure the new limit is not below
the concurrently-changing counter value. We read the counter and check
that the limit is not below the counter before the swap. After the swap,
we read the counter again and retry in case the counter is incremented as
this may violate the requirement. Even though the page_counter_try_charge
can see the old limit, it is guaranteed that the counter is not above the
old limit after the increment. So in case the new limit is not below the
old limit, the counter is guaranteed to be not above the new limit too.
We can skip the retry in this case to optimize a little bit.
Link: https://lkml.kernel.org/r/20220821154055.109635-1-minhquangbui99@gmail.com
Signed-off-by: Bui Quang Minh <minhquangbui99@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
