In the following code, the second call to the mas_node_count will return
-ENOMEM:
mas_node_count(mas, MAPLE_ALLOC_SLOTS + 1);
mas_node_count(mas, MAPLE_ALLOC_SLOTS * 2 + 2);
This is because there may be some full maple_alloc node in current maple
state. Use full maple_alloc node will make max_req equal to 0. And it
leads to mt_alloc_bulk return 0. As a result, mas_node_count set mas.node
to MA_ERROR(-ENOMEM).
Find a non-full maple_alloc node, and if necessary, use this non-full node
in the next while loop.
Link: https://lkml.kernel.org/r/20240626160631.3636515-1-Liam.Howlett@oracle.com
Fixes: 54a611b605 ("Maple Tree: add new data structure")
Signed-off-by: Jiazi Li <jqqlijiazi@gmail.com>
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Suggested-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
refresh_zone_stat_thresholds function has two loops which is expensive for
higher number of CPUs and NUMA nodes.
Below is the rough estimation of total iterations done by these loops
based on number of NUMA and CPUs.
Total number of iterations: nCPU * 2 * Numa * mCPU
Where:
nCPU = total number of CPUs
Numa = total number of NUMA nodes
mCPU = mean value of total CPUs (e.g., 512 for 1024 total CPUs)
For the system under test with 16 NUMA nodes and 1024 CPUs, this results
in a substantial increase in the number of loop iterations during boot-up
when NUMA is enabled:
No NUMA = 1024*2*1*512 = 1,048,576 : Here refresh_zone_stat_thresholds
takes around 224 ms total for all the CPUs in the system under test.
16 NUMA = 1024*2*16*512 = 16,777,216 : Here refresh_zone_stat_thresholds
takes around 4.5 seconds total for all the CPUs in the system under test.
Calling this for each CPU is expensive when there are large number of CPUs
along with multiple NUMAs. Fix this by deferring
refresh_zone_stat_thresholds to be called later at once when all the
secondary CPUs are up. Also, register the DYN hooks to keep the existing
hotplug functionality intact.
Link: https://lkml.kernel.org/r/1723443220-20623-1-git-send-email-ssengar@linux.microsoft.com
Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>
Acked-by: Christoph Lameter <cl@linux.com>
Reviewed-by: Srivatsa S. Bhat (Microsoft) <srivatsa@csail.mit.edu>
Cc: Saurabh Singh Sengar <ssengar@microsoft.com>
Cc: Wei Liu <wei.liu@kernel.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
zswap_invalidation simply calls xa_erase, which acquires the Xarray lock
first, then does a look up. This has a higher overhead even if zswap is
not used or the tree is empty.
So instead, do a very lightweight xa_empty check first, if there is
nothing to erase, don't touch the lock or the tree.
Using xa_empty rather than zswap_never_enabled is more helpful as it cover
both case where zswap wes never used or the particular range doesn't have
any zswap entry. And it's safe as the swap slot should be currently
pinned by caller with HAS_CACHE.
Sequential SWAP in/out tests with zswap disabled showed a minor
performance gain, SWAP in of zero page with zswap enabled also showed a
performance gain. (swapout is basically unchanged so only test one case):
Swapout of 2G zero page using brd as SWAP, zswap disabled
(total time, 4 testrun, +0.1%):
Before: 1705013 us 1703119 us 1704335 us 1705848 us.
After: 1703579 us 1710640 us 1703625 us 1708699 us.
Swapin of 2G zero page using brd as SWAP, zswap disabled
(total time, 4 testrun, -3.5%):
Before: 1912312 us 1915692 us 1905837 us 1912706 us.
After: 1845354 us 1849691 us 1845868 us 1841828 us.
Swapin of 2G zero page using brd as SWAP, zswap enabled
(total time, 4 testrun, -3.3%):
Before: 1897994 us 1894681 us 1899982 us 1898333 us
After: 1835894 us 1834113 us 1832047 us 1833125 us
Swapin of 2G random page using brd as SWAP, zswap enabled
(total time, 4 testrun, -0.1%):
Before: 4519747 us 4431078 us 4430185 us 4439999 us
After: 4492176 us 4437796 us 4434612 us 4434289 us
And the performance is very slightly better or unchanged for
build kernel test with zswap enabled or disabled.
Build Linux Kernel with defconfig and -j32 in 1G memory cgroup,
using brd SWAP, zswap disabled (sys time in seconds, 6 testrun, -0.1%):
Before: 1648.83 1653.52 1666.34 1665.95 1663.06 1656.67
After: 1651.36 1661.89 1645.70 1657.45 1662.07 1652.83
Build Linux Kernel with defconfig and -j32 in 2G memory cgroup,
using brd SWAP zswap enabled (sys time in seconds, 6 testrun, -0.3%):
Before: 1240.25 1254.06 1246.77 1265.92 1244.23 1227.74
After: 1226.41 1218.21 1249.12 1249.13 1244.39 1233.01
Link: https://lkml.kernel.org/r/20241011171950.62684-1-ryncsn@gmail.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Acked-by: Yosry Ahmed <yosryahmed@google.com>
Cc: Barry Song <v-songbaohua@oppo.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Chris Li <chrisl@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Nhat Pham <nphamcs@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
For clarity. It's increasingly hard to reason about the code, when KASLR
is moving around the boundaries. In this case where KASLR is randomizing
the location of the kernel image within physical memory, the maximum
number of address bits for physical memory has not changed.
What has changed is the ending address of memory that is allowed to be
directly mapped by the kernel.
Let's name the variable, and the associated macro accordingly.
Also, enhance the comment above the direct_map_physmem_end definition,
to further clarify how this all works.
Link: https://lkml.kernel.org/r/20241009025024.89813-1-jhubbard@nvidia.com
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Pankaj Gupta <pankaj.gupta@amd.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Will Deacon <will@kernel.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Jordan Niethe <jniethe@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Hugetlb mappings will no longer be special cased but rather go through the
generic mm_get_unmapped_area_vmflags function. For that to happen, let us
remove the .get_unmapped_area from hugetlbfs_file_operations struct, and
hint __get_unmapped_area that it should not send hugetlb mappings through
thp_get_unmapped_area_vmflags but through mm_get_unmapped_area_vmflags.
Create also a function called hugetlb_mmap_check_and_align() where a
couple of safety checks are being done and the addr is aligned to the huge
page size. Otherwise we will have to do this in every single function,
which duplicates quite a lot of code.
Link: https://lkml.kernel.org/r/20241007075037.267650-7-osalvador@suse.de
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Cc: David Hildenbrand <david@redhat.com>
Cc: Donet Tom <donettom@linux.ibm.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Peter Xu <peterx@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "Unify hugetlb into arch_get_unmapped_area functions", v4.
This is an attempt to get rid of a fair amount of duplicated code wrt.
hugetlb and *get_unmapped_area* functions.
HugeTLB registers a .get_unmapped_area function which gets called from
__get_unmapped_area().
hugetlb_get_unmapped_area() is defined by a bunch of architectures and
it also has a generic definition for those that do not define it.
Short-long story is that there is a ton of duplicated code between
specific hugetlb *_get_unmapped_area_* functions and mm-core functions,
so we can do better by teaching arch_get_unmapped_area* functions how
to deal with hugetlb mappings.
Note that not a lot of things need to be taught though.
hugetlb_get_unmapped_area, that gets called for hugetlb mappings, runs
some sanity checks prior to calling mm_get_unmapped_area_vmflags(), so we
do not need to that down the road in the respective
{generic,arch}_get_unmapped_area* functions.
More information can be found in the respective patches.
LTP mmapstress hugetlb selftests were ran succesfully on:
This patch (of 9):
We want to stop special casing hugetlb mappings and make them go through
generic channels, so teach generic_get_unmapped_area{_topdown} to handle
those. The main difference is that we set info.align_mask for huge
mappings.
Link: https://lkml.kernel.org/r/20241007075037.267650-1-osalvador@suse.de
Link: https://lkml.kernel.org/r/20241007075037.267650-2-osalvador@suse.de
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Cc: David Hildenbrand <david@redhat.com>
Cc: Donet Tom <donettom@linux.ibm.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Peter Xu <peterx@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Performance analysis using branch annotation on a fleet of 200 hosts
running web servers revealed that the 'unlikely' hint in
vms_gather_munmap_vmas() was 100% consistently incorrect. In all observed
cases, the branch behavior contradicted the hint.
Remove the 'unlikely' qualifier from the condition checking 'vms->uf'. By
doing so, we allow the compiler to make optimization decisions based on
its own heuristics and profiling data, rather than relying on a static
hint that has proven to be inaccurate in real-world scenarios.
Link: https://lkml.kernel.org/r/20241004164832.218681-1-leitao@debian.org
Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Many maple tree values output when an mt_validate() or equivalent hits an
issue utilise tagged pointers, most notably parent nodes. Also some
pivots/slots contain meaningful values, output as pointers, such as the
index of the last entry with data for example.
All pointer values such as this are destroyed by kernel pointer hashing
rendering the debug output obtained from CONFIG_DEBUG_VM_MAPLE_TREE
considerably less usable.
Update this code to output the raw pointers using %px rather than %p when
CONFIG_DEBUG_VM_MAPLE_TREE is defined. This is justified, as the use of
this configuration flag indicates that this is a test environment.
Userland does not understand %px, so use %p there.
In an abundance of caution, if CONFIG_DEBUG_VM_MAPLE_TREE is not set, also
use %p to avoid exposing raw kernel pointers except when we are positive a
testing mode is enabled.
This was inspired by the investigation performed in recent debugging
efforts around a maple tree regression [0] where kernel pointer tagging had
to be disabled in order to obtain truly meaningful and useful data.
[0]:https://lore.kernel.org/all/20241001023402.3374-1-spasswolf@web.de/
Link: https://lkml.kernel.org/r/20241007115335.90104-1-lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Currently mapping_try_invalidate() and invalidate_inode_pages2_range()
traverses the xarray in batches and then for each batch, maintains and
sets the flag named xa_has_values if the batch has a shadow entry to clear
the entries at the end of the iteration.
However they forgot to reset the flag at the end of the iteration which
causes them to always try to clear the shadow entries in the subsequent
iterations where there might not be any shadow entries.
Fix this inefficiency.
Link: https://lkml.kernel.org/r/20241002225150.2334504-1-shakeel.butt@linux.dev
Fixes: 61c663e020 ("mm/truncate: batch-clear shadow entries")
Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: Yu Zhao <yuzhao@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
There is a unnecessary return statement at the end of void function
cma_activate_area. This can be dropped.
While at it, also fix another warning related to unsigned.
These are reported by checkpatch as well.
WARNING: Prefer 'unsigned int' to bare use of 'unsigned'
+unsigned cma_area_count;
WARNING: void function return statements are not generally useful
+ return;
+}
Link: https://lkml.kernel.org/r/20240927181637.19941-1-quic_pintu@quicinc.com
Signed-off-by: Pintu Kumar <quic_pintu@quicinc.com>
Cc: Pintu Agarwal <pintu.ping@gmail.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The kernel invalidates the page cache in batches of PAGEVEC_SIZE. For
each batch, it traverses the page cache tree and collects the entries
(folio and shadow entries) in the struct folio_batch. For the shadow
entries present in the folio_batch, it has to traverse the page cache tree
for each individual entry to remove them. This patch optimize this by
removing them in a single tree traversal.
To evaluate the changes, we created 200GiB file on a fuse fs and in a
memcg. We created the shadow entries by triggering reclaim through
memory.reclaim in that specific memcg and measure the simple
fadvise(DONTNEED) operation.
# time xfs_io -c 'fadvise -d 0 ${file_size}' file
time (sec)
Without 5.12 +- 0.061
With-patch 4.19 +- 0.086 (18.16% decrease)
Link: https://lkml.kernel.org/r/20240925224716.2904498-3-shakeel.butt@linux.dev
Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Chris Mason <clm@fb.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Omar Sandoval <osandov@osandov.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "mm: optimize shadow entries removal", v2.
Some of our production workloads which processes a large amount of data
spends considerable amount of CPUs on truncation and invalidation of large
sized files (100s of GiBs of size). Tracing the operations showed that
most of the time is in shadow entries removal. This patch series
optimizes the truncation and invalidation operations.
This patch (of 2):
The kernel truncates the page cache in batches of PAGEVEC_SIZE. For each
batch, it traverses the page cache tree and collects the entries (folio
and shadow entries) in the struct folio_batch. For the shadow entries
present in the folio_batch, it has to traverse the page cache tree for
each individual entry to remove them. This patch optimize this by
removing them in a single tree traversal.
On large machines in our production which run workloads manipulating large
amount of data, we have observed that a large amount of CPUs are spent on
truncation of very large files (100s of GiBs file sizes). More
specifically most of time was spent on shadow entries cleanup, so
optimizing the shadow entries cleanup, even a little bit, has good impact.
To evaluate the changes, we created 200GiB file on a fuse fs and in a
memcg. We created the shadow entries by triggering reclaim through
memory.reclaim in that specific memcg and measure the simple truncation
operation.
# time truncate -s 0 file
time (sec)
Without 5.164 +- 0.059
With-patch 4.21 +- 0.066 (18.47% decrease)
Link: https://lkml.kernel.org/r/20240925224716.2904498-1-shakeel.butt@linux.dev
Link: https://lkml.kernel.org/r/20240925224716.2904498-2-shakeel.butt@linux.dev
Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Chris Mason <clm@fb.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Omar Sandoval <osandov@osandov.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
