Currently zram allocates 2 physically contiguous pages per-CPU's
compression stream (we may have up to 4 streams per-CPU). Since those
buffers are per-CPU we allocate them from CPU hotplug path, which may have
higher risks of failed allocations on devices with fragmented memory.
Switch to virtually contiguous allocations - crypto comp does not seem
impose requirements on compression working buffers to be physically
contiguous.
Link: https://lkml.kernel.org/r/20240213065400.6561-1-21cnbao@gmail.com
Signed-off-by: Barry Song <v-songbaohua@oppo.com>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
All platforms could benefit from page order check against MAX_PAGE_ORDER
before allocating a CMA area for gigantic hugetlb pages. Let's move this
check from individual platforms to generic hugetlb.
Link: https://lkml.kernel.org/r/20240209054221.1403364-1-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Jane Chu <jane.chu@oracle.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The reclaimable number of anon pages used to set initial reclaim priority
is only based on get_swappiness(). Use can_reclaim_anon_pages() to
include NUMA node demotion.
Also move the swappiness handling of when !__GFP_IO in
try_to_shrink_lruvec() into isolate_folios().
Link: https://lkml.kernel.org/r/20240214060538.3524462-6-kinseyho@google.com
Signed-off-by: Kinsey Ho <kinseyho@google.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Donet Tom <donettom@linux.vnet.ibm.com>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Rename max_seq to seq in struct lru_gen_mm_walk to keep consistent with
struct lru_gen_mm_state. Note that seq is not always up to date with
max_seq from lru_gen_folio.
No functional changes.
Link: https://lkml.kernel.org/r/20240214060538.3524462-5-kinseyho@google.com
Signed-off-by: Kinsey Ho <kinseyho@google.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Donet Tom <donettom@linux.vnet.ibm.com>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
struct lruvec* is already a field of struct lru_gen_mm_walk. Remove the
parameter struct lruvec* into functions that already have access to struct
lru_gen_mm_walk*.
Also, we do not need to handle reset histogram stats when
!should_walk_mmu(). Remove the call to reset_mm_stats() in
iterate_mm_list_nowalk().
Link: https://lkml.kernel.org/r/20240214060538.3524462-4-kinseyho@google.com
Signed-off-by: Kinsey Ho <kinseyho@google.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Donet Tom <donettom@linux.vnet.ibm.com>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
scan_control *sc does not need to be passed into should_run_aging(), as it
provides only the reclaim priority. This can be moved to
get_nr_to_scan().
Refactor should_run_aging() and get_nr_to_scan() to improve code
readability. No functional changes.
Link: https://lkml.kernel.org/r/20240214060538.3524462-3-kinseyho@google.com
Signed-off-by: Kinsey Ho <kinseyho@google.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Donet Tom <donettom@linux.vnet.ibm.com>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "mm/mglru: code cleanup and refactoring"
This provides MGLRU code cleanup and refactoring for better readability.
This patch (of 5):
struct scan_control *sc is currently passed into try_to_inc_max_seq() and
run_aging(). This parameter is not used.
Drop the unused parameter struct scan_control *sc. No functional change.
Link: https://lkml.kernel.org/r/20240214060538.3524462-1-kinseyho@google.com
Link: https://lkml.kernel.org/r/20240214060538.3524462-2-kinseyho@google.com
Signed-off-by: Kinsey Ho <kinseyho@google.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Donet Tom <donettom@linux.vnet.ibm.com>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The out-of-bounds test allocates an object that is three bytes too short
in order to validate the bounds checking. Starting with gcc-14, this
causes a compile-time warning as gcc has grown smart enough to understand
the sizeof() logic:
mm/kasan/kasan_test.c: In function 'kmalloc_oob_16':
mm/kasan/kasan_test.c:443:14: error: allocation of insufficient size '13' for type 'struct <anonymous>' with size '16' [-Werror=alloc-size]
443 | ptr1 = kmalloc(sizeof(*ptr1) - 3, GFP_KERNEL);
| ^
Hide the actual computation behind a RELOC_HIDE() that ensures
the compiler misses the intentional bug.
Link: https://lkml.kernel.org/r/20240212111609.869266-1-arnd@kernel.org
Fixes: 3f15801cdc ("lib: add kasan test module")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The memalloc_noreclaim_save() function currently has no documentation
comment, so the implications of its usage are not obvious. Namely that it
not only prevents entering reclaim (as the name suggests), but also allows
using all memory reserves and thus should be only used in contexts that
are allocating memory to free memory. This may lead to new improper
usages being added.
Thus add a documenting comment, based on the description of
__GFP_MEMALLOC. While at it, also document memalloc_pin_save() so that
all the memalloc_ scopes are documented. For those already documented,
add missing Return: descriptions, and mark Context: description per
kernel-docs style guide.
In the comments describing the relevant PF_MEMALLOC flags, refer to their
scope setting functions.
[vbabka@suse.cz: fix issues that Mike pointed out]
Link: https://lkml.kernel.org/r/20240215095827.13756-2-vbabka@suse.cz
Link: https://lkml.kernel.org/r/20240212182950.32730-2-vbabka@suse.cz
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Mike Rapoport (IBM) <rppt@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
We may encounter duplicate entry in the zswap_store():
1. swap slot that freed to per-cpu swap cache, doesn't invalidate
the zswap entry, then got reused. This has been fixed.
2. !exclusive load mode, swapin folio will leave its zswap entry
on the tree, then swapout again. This has been removed.
3. one folio can be dirtied again after zswap_store(), so need to
zswap_store() again. This should be handled correctly.
So we must invalidate the old duplicate entry before inserting the
new one, which actually doesn't have to be done at the beginning
of zswap_store().
The good point is that we don't need to lock the tree twice in the normal
store success path. And cleanup the loop as we are here.
Note we still need to invalidate the old duplicate entry when store failed
or zswap is disabled , otherwise the new data in swapfile could be
overwrite by the old data in zswap pool when lru writeback.
Link: https://lkml.kernel.org/r/20240209044112.3883835-1-chengming.zhou@linux.dev
Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Yosry Ahmed <yosryahmed@google.com>
Acked-by: Chris Li <chrisl@kernel.org>
Acked-by: Nhat Pham <nphamcs@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Every test result report in the compaction test prints a distinct log
messae, and some of the reports print a name that varies at runtime. This
causes problems for automation since a lot of automation software uses the
printed string as the name of the test, if the name varies from run to run
and from pass to fail then the automation software can't identify that a
test changed result or that the same tests are being run.
Refactor the logging to use a consistent name when printing the result of
the test, printing the existing messages as diagnostic information instead
so they are still available for people trying to interpret the results.
Link: https://lkml.kernel.org/r/20240209-kselftest-mm-cleanup-v1-2-a3c0386496b5@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: Muhammad Usama Anjum <usama.anjum@collabora.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "selftests/mm: Output cleanups for the compaction test".
A couple of small updates for the check_compaction selftest which make
it play more nicely with test automation systems.
This patch (of 2):
When the compaction test is run it checks to make sure that prerequistives
the test requires are available and skips the tests if not. When this
happens we log the test as a pass rather than a skip, log as a skip so
that the distinction is clear and automation can see unexpected skips.
Link: https://lkml.kernel.org/r/20240209-kselftest-mm-cleanup-v1-0-a3c0386496b5@kernel.org
Link: https://lkml.kernel.org/r/20240209-kselftest-mm-cleanup-v1-1-a3c0386496b5@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: Muhammad Usama Anjum <usama.anjum@collabora.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Refactor compact_node() to handle both proactive and synchronous compact
memory, which cleanups code a bit.
Link: https://lkml.kernel.org/r/20240208013607.1731817-1-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This adds the following new sysfs file tracking the number of successfully
released pages from a given CMA heap area. This file will be available
via CONFIG_CMA_SYSFS and help in determining active CMA pages available on
the CMA heap area. This adds a new 'nr_pages_released' (CONFIG_CMA_SYSFS)
into 'struct cma' which gets updated during cma_release().
/sys/kernel/mm/cma/<cma-heap-area>/release_pages_success
After this change, an user will be able to find active CMA pages available
in a given CMA heap area via the following method.
Active pages = alloc_pages_success - release_pages_success
That's valuable information for both software designers, and system admins
as it allows them to tune the number of CMA pages available in the system.
This increases user visibility for allocated CMA area and its
utilization.
Link: https://lkml.kernel.org/r/20240206045731.472759-1-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
DAMON debugfs selftests dependency checker assumes debugfs would be
mounted at /sys/kernel/debug. That would be ok for many cases, but some
systems might mounted the file system on some different places. Parse the
real mount point using /proc/mounts file.
Link: https://lkml.kernel.org/r/20240207203134.69976-9-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Commit ebb3f994dd ("mm/damon/dbgfs: fix 'struct pid' leaks in
'dbgfs_target_ids_write()'") fixes a pid leak bug in DAMON debugfs
interface, namely dbgfs_target_ids_write() function. Add a selftest for
the issue to prevent the problem from mistakenly recurring.
Link: https://lkml.kernel.org/r/20240207203134.69976-8-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
commit 3479641796 ("mm/damon/dbgfs: protect targets destructions with
kdamond_lock") fixed a race of DAMON debugfs interface. Specifically, the
race was happening between target_ids_read() and dbgfs_before_terminate().
Add a test for the issue to prevent the problem from accidentally
recurring.
Link: https://lkml.kernel.org/r/20240207203134.69976-7-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Add a selftest for DAMOS apply intervals. It runs two schemes having
different apply interval agains an artificial memory access workload, and
check if the scheme with smaller apply interval was applied more
frequently.
Link: https://lkml.kernel.org/r/20240207203134.69976-6-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Add a selftest for verifying the DAMOS quota feature. The test is very
similar to sysfs_update_schemes_tried_regions_wss_estimation.py. It
starts an artificial workload of 20 MiB working set, run DAMON to find the
working set size, but with 1 MiB/100 ms size quota. Then, it collect the
DAMON-found working set size every 100 ms and check if the quota was
always applied as expected. For the confirmation, the tests shows the
stat-applied region size and the qt_exceeds stat.
Link: https://lkml.kernel.org/r/20240207203134.69976-5-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Update the test-purpose DAMON sysfs control Python module to support DAMOS
apply interval.
Link: https://lkml.kernel.org/r/20240207203134.69976-4-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Update the test-purpose DAMON sysfs control Python module to support DAMOS
stats.
Link: https://lkml.kernel.org/r/20240207203134.69976-3-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "selftests/damon: add more tests for core functionalities and
corner cases".
Continue DAMON selftests' test coverage improvement works with a trivial
improvement of the test code itself. The sequence of the patches in
patchset is as follows.
The first five patches add two DAMON core functionalities tests. Those
begins with three patches (patches 1-3) that update the test-purpose DAMON
sysfs interface wrapper to support DAMOS quota, stats, and apply interval
features, respectively. The fourth patch implements and adds a selftest
for DAMOS quota feature, using the DAMON sysfs interface wrapper's newly
added support of the quota and the stats feature. The fifth patch further
implements and adds a selftest for DAMOS apply interval using the DAMON
sysfs interface wrapper's newly added support of the apply interval and
the stats feature.
Two patches (patches 6 and 7) for implementing and adding two corner cases
handling selftests follow. Those try to avoid two previously fixed bugs
from recurring.
Finally, a patch for making DAMON debugfs selftests dependency checker to
use /proc/mounts instead of the hard-coded mount point assumption follows.
This patch (of 8):
Update the test-purpose DAMON sysfs control Python module to support DAMOS
quota.
Link: https://lkml.kernel.org/r/20240207203134.69976-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20240207203134.69976-2-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Some architectures, such as arm, have implemented optimized copy_page for
full page copying.
Replace the full page memcpy with copy_page to take advantage of the
optimization.
Link: https://lkml.kernel.org/r/20231007070554.8657-1-mark-pk.tsai@mediatek.com
Signed-off-by: Mark-PK Tsai <mark-pk.tsai@mediatek.com>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: YJ Chiang <yj.chiang@mediatek.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Currently, when a demotion occurs, it will prioritize selecting a node
from the preferred targets as the destination node for the demotion. If
the preferred node does not meet the requirements, it will try from all
the lower memory tier nodes until it finds a suitable demotion destination
node or ultimately fails.
However, the demotion target information isn't exposed to the users,
especially the preferred target information, which relies on more factors.
This makes it hard for users to understand the exact demotion behavior.
Rather than having a new sysfs interface to expose this information,
printing directly to kernel messages, just like the current page
allocation fallback order does.
A dmesg example with this patch is as follows:
[ 0.704860] Demotion targets for Node 0: null
[ 0.705456] Demotion targets for Node 1: null
// node 2 is onlined
[ 32.259775] Demotion targets for Node 0: perferred: 2, fallback: 2
[ 32.261290] Demotion targets for Node 1: perferred: 2, fallback: 2
[ 32.262726] Demotion targets for Node 2: null
// node 3 is onlined
[ 42.448809] Demotion targets for Node 0: perferred: 2, fallback: 2-3
[ 42.450704] Demotion targets for Node 1: perferred: 2, fallback: 2-3
[ 42.452556] Demotion targets for Node 2: perferred: 3, fallback: 3
[ 42.454136] Demotion targets for Node 3: null
// node 4 is onlined
[ 52.676833] Demotion targets for Node 0: perferred: 2, fallback: 2-4
[ 52.678735] Demotion targets for Node 1: perferred: 2, fallback: 2-4
[ 52.680493] Demotion targets for Node 2: perferred: 4, fallback: 3-4
[ 52.682154] Demotion targets for Node 3: null
[ 52.683405] Demotion targets for Node 4: null
// node 5 is onlined
[ 62.931902] Demotion targets for Node 0: perferred: 2, fallback: 2-5
[ 62.938266] Demotion targets for Node 1: perferred: 5, fallback: 2-5
[ 62.943515] Demotion targets for Node 2: perferred: 4, fallback: 3-4
[ 62.947471] Demotion targets for Node 3: null
[ 62.949908] Demotion targets for Node 4: null
[ 62.952137] Demotion targets for Node 5: perferred: 3, fallback: 3-4
Regarding this requirement, we have previously discussed [1]. The initial
proposal involved introducing a new sysfs interface. However, due to
concerns about potential changes and compatibility issues with the
interface in the future, a consensus was not reached with the community.
Therefore, this time, we are directly printing out the information.
[1] https://lore.kernel.org/all/d1d5add8-8f4a-4578-8bf0-2cbe79b09989@fujitsu.com/
Link: https://lkml.kernel.org/r/20240206020151.605516-1-lizhijian@fujitsu.com
Signed-off-by: Li Zhijian <lizhijian@fujitsu.com>
Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
DAMON sysfs interface need to access kdamond-touching data for some of
kdamond user commands. It uses ->after_aggregation() kdamond callback to
safely access the data in the case. It had to use the aggregation
interval callback because that was the only callback that users can access
complete monitoring results.
Since patch series "mm/damon: provide pseudo-moving sum based access
rate", which starts from commit 78fbfb155d ("mm/damon/core: define and
use a dedicated function for region access rate update"), DAMON provides
good-to-use quality moitoring results for every sampling interval. It
aims to help users who need to quickly retrieve the monitoring results.
When the aggregation interval is set too long and therefore waiting for
the aggregation interval can degrade user experience, or when the access
pattern is expected to be significantly changed[1] could be such cases.
However, because DAMON sysfs interface is still handling the commands per
aggregation interval, the end user cannot get the benefit. Update DAMON
sysfs interface to handle kdamond commands for every sampling interval if
applicable. Specifically, all kdamond data accessing commands except
'commit' command are applicable.
[1] https://lore.kernel.org/r/20240129121316.GA9706@cuiyangpei
Link: https://lkml.kernel.org/r/20240206025158.203097-1-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: xiongping1 <xiongping1@xiaomi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
alloc_and_dissolve_hugetlb_folio() preallocates a new hugetlb page before
it takes hugetlb_lock. In 3 out of 4 cases the page is not really used
and therefore the newly allocated page is just freed right away. This is
wasteful and it might cause pre-mature failures in those cases.
Address that by moving the allocation down to the only case (hugetlb page
is really in the free pages pool). We need to drop hugetlb_lock to do so
and therefore need to recheck the page state after regaining it.
The patch is more of a cleanup than an actual fix to an existing problem.
There are no known reports about pre-mature failures.
Link: https://lkml.kernel.org/r/62890fd60b1ecd5bf1cdc476c973f60fe37aa0cb.1707181934.git.baolin.wang@linux.alibaba.com
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Muchun Song <muchun.song@linux.dev>
Cc: David Hildenbrand <david@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
pte_mkdirty() sets both _PAGE_DIRTY and _PAGE_SOFT_DIRTY bits. The
_PAGE_SOFT_DIRTY can get set even if it wasn't set on original page before
migration. This makes non-soft-dirty pages soft-dirty just because of
migration/compaction. Clear the _PAGE_SOFT_DIRTY flag if it wasn't set on
original page.
By definition of soft-dirty feature, there can be spurious soft-dirty
pages because of kernel's internal activity such as VMA merging or
migration/compaction. This patch is eliminating the spurious soft-dirty
pages because of migration/compaction.
Link: https://lkml.kernel.org/r/20240206084838.34560-1-usama.anjum@collabora.com
Signed-off-by: Paul Gofman <pgofman@codeweavers.com>
Signed-off-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Acked-by: Andrei Vagin <avagin@gmail.com>
Cc: Michał Mirosław <emmir@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Since we don't need to leave zswap entry on the zswap tree anymore,
we should remove it from tree once we find it from the tree.
Then after using it, we can directly free it, no concurrent path
can find it from tree. Only the shrinker can see it from lru list,
which will also double check under tree lock, so no race problem.
So we don't need refcount in zswap entry anymore and don't need to
take the spinlock for the second time to invalidate it.
The side effect is that zswap_entry_free() maybe not happen in tree
spinlock, but it's ok since nothing need to be protected by the lock.
Link: https://lkml.kernel.org/r/20240201-b4-zswap-invalidate-entry-v2-6-99d4084260a0@bytedance.com
Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Reviewed-by: Nhat Pham <nphamcs@gmail.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The !zswap_exclusive_loads_enabled mode will leave compressed copy in
the zswap tree and lru list after the folio swapin.
There are some disadvantages in this mode:
1. It's a waste of memory since there are two copies of data, one is
folio, the other one is compressed data in zswap. And it's unlikely
the compressed data is useful in the near future.
2. If that folio is dirtied, the compressed data must be not useful,
but we don't know and don't invalidate the trashy memory in zswap.
3. It's not reclaimable from zswap shrinker since zswap_writeback_entry()
will always return -EEXIST and terminate the shrinking process.
On the other hand, the only downside of zswap_exclusive_loads_enabled
is a little more cpu usage/latency when compression, and the same if
the folio is removed from swapcache or dirtied.
More explanation by Johannes on why we should consider exclusive load
as the default for zswap:
Caching "swapout work" is helpful when the system is thrashing. Then
recently swapped in pages might get swapped out again very soon. It
certainly makes sense with conventional swap, because keeping a clean
copy on the disk saves IO work and doesn't cost any additional memory.
But with zswap, it's different. It saves some compression work on a
thrashing page. But the act of keeping compressed memory contributes
to a higher rate of thrashing. And that can cause IO in other places
like zswap writeback and file memory.
And the A/B test results of the kernel build in tmpfs with limited memory
can support this theory:
!exclusive exclusive
real 63.80 63.01
user 1063.83 1061.32
sys 290.31 266.15
workingset_refault_anon 2383084.40 1976397.40
workingset_refault_file 44134.00 45689.40
workingset_activate_anon 837878.00 728441.20
workingset_activate_file 4710.00 4085.20
workingset_restore_anon 732622.60 639428.40
workingset_restore_file 1007.00 926.80
workingset_nodereclaim 0.00 0.00
pgscan 14343003.40 12409570.20
pgscan_kswapd 0.00 0.00
pgscan_direct 14343003.40 12409570.20
pgscan_khugepaged 0.00 0.00
Link: https://lkml.kernel.org/r/20240201-b4-zswap-invalidate-entry-v2-5-99d4084260a0@bytedance.com
Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Acked-by: Yosry Ahmed <yosryahmed@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Nhat Pham <nphamcs@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
cat /sys/kernel/debug/zswap/duplicate_entry
2086447
When testing, the duplicate_entry value is very high, but no warning
message in the kernel log. From the comment of duplicate_entry "Duplicate
store was encountered (rare)", it seems something goes wrong.
Actually it's incremented in the beginning of zswap_store(), which found
its zswap entry has already on the tree. And this is a normal case, since
the folio could leave zswap entry on the tree after swapin, later it's
dirtied and swapout/zswap_store again, found its original zswap entry.
So duplicate_entry should be only incremented in the real bug case, which
already have "WARN_ON(1)", it looks redundant to count bug case, so this
patch just remove it.
Link: https://lkml.kernel.org/r/20240201-b4-zswap-invalidate-entry-v2-4-99d4084260a0@bytedance.com
Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Nhat Pham <nphamcs@gmail.com>
Acked-by: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
When the shrinker encounter an existing folio in swap cache, it means we
are shrinking into the warmer region. We should terminate shrinking if
we're in the dynamic shrinker context.
This patch add LRU_STOP to support this, to avoid overshrinking.
Link: https://lkml.kernel.org/r/20240201-b4-zswap-invalidate-entry-v2-3-99d4084260a0@bytedance.com
Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Nhat Pham <nphamcs@gmail.com>
Reviewed-by: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
During testing I found there are some times the zswap_writeback_entry()
return -ENOMEM, which is not we expected:
bpftrace -e 'kr:zswap_writeback_entry {@[(int32)retval]=count()}'
@[-12]: 1563
@[0]: 277221
The reason is that __read_swap_cache_async() return NULL because
swapcache_prepare() failed. The reason is that we won't invalidate zswap
entry when swap entry freed to the per-cpu pool, these zswap entries are
still on the zswap tree and lru list.
This patch moves the invalidation ahead to when swap entry freed to the
per-cpu pool, since there is no any benefit to leave trashy zswap entry on
the tree and lru list.
With this patch:
bpftrace -e 'kr:zswap_writeback_entry {@[(int32)retval]=count()}'
@[0]: 259744
Note: large folio can't have zswap entry for now, so don't bother
to add zswap entry invalidation in the large folio swap free path.
Link: https://lkml.kernel.org/r/20240201-b4-zswap-invalidate-entry-v2-2-99d4084260a0@bytedance.com
Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Reviewed-by: Nhat Pham <nphamcs@gmail.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "mm/zswap: optimize zswap lru list", v2.
This series is motivated when observe the zswap lru list shrinking, noted
there are some unexpected cases in zswap_writeback_entry().
bpftrace -e 'kr:zswap_writeback_entry {@[(int32)retval]=count()}'
There are some -ENOMEM because when the swap entry is freed to per-cpu
swap pool, it doesn't invalidate/drop zswap entry. Then the shrinker
encounter these trashy zswap entries, it can't be reclaimed and return
-ENOMEM.
So move the invalidation ahead to when swap entry freed to the per-cpu
swap pool, since there is no any benefit to leave trashy zswap entries on
the zswap tree and lru list.
Another case is -EEXIST, which is seen more in the case of
!zswap_exclusive_loads_enabled, in which case the swapin folio will leave
compressed copy on the tree and lru list. And it can't be reclaimed until
the folio is removed from swapcache.
Changing to zswap_exclusive_loads_enabled mode will invalidate when folio
swapin, which has its own drawback if that folio is still clean in
swapcache and swapout again, we need to compress it again. Please see the
commit for details on why we choose exclusive load as the default for
zswap.
Another optimization for -EEXIST is that we add LRU_STOP to support
terminating the shrinking process to avoid evicting warmer region.
Testing using kernel build in tmpfs, one 50GB swapfile and
zswap shrinker_enabled, with memory.max set to 2GB.
mm-unstable zswap-optimize
real 63.90s 63.25s
user 1064.05s 1063.40s
sys 292.32s 270.94s
The main optimization is in sys cpu, about 7% improvement.
This patch (of 6):
Add more comments in shrink_memcg_cb() to describe the deref dance which
is implemented to fix race problem between lru writeback and swapoff, and
the reason why we rotate the entry at the beginning.
Also fix the stale comments in zswap_writeback_entry(), and add more
comments to state that we only deref the tree after we get the swapcache
reference.
Link: https://lkml.kernel.org/r/20240201-b4-zswap-invalidate-entry-v2-0-99d4084260a0@bytedance.com
Link: https://lkml.kernel.org/r/20240201-b4-zswap-invalidate-entry-v2-1-99d4084260a0@bytedance.com
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Suggested-by: Yosry Ahmed <yosryahmed@google.com>
Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Yosry Ahmed <yosryahmed@google.com>
Reviewed-by: Nhat Pham <nphamcs@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Now that the driver core can properly handle constant struct bus_type,
move the memory_tier_subsys variable to be a constant structure as well,
placing it into read-only memory which can not be modified at runtime.
Link: https://lkml.kernel.org/r/20240204-bus_cleanup-mm-v1-1-00f49286f164@marliere.net
Signed-off-by: Ricardo B. Marliere <ricardo@marliere.net>
Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
too_many_isolated() should return bool as does the similar
too_many_isolated() in mm/compaction.c.
Link: https://lkml.kernel.org/r/20240205042618.108140-1-gehao@kylinos.cn
Signed-off-by: Hao Ge <gehao@kylinos.cn>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
There is no real difference between the global area, and other
additionally configured CMA areas via CONFIG_CMA_AREAS that always
defaults without user input. This makes MAX_CMA_AREAS same as
CONFIG_CMA_AREAS, also incrementing its default values, thus maintaining
current default for MAX_CMA_AREAS both for UMA and NUMA systems.
Link: https://lkml.kernel.org/r/20240205051929.298559-1-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
All pr_debug() prints in (mm/cma.c) could be enabled via standard Makefile
based method. Besides cma_debug_show_areas() should always be called
during cma_alloc() failure path. This seemingly redundant config,
CONFIG_CMA_DEBUG can be dropped without any problem.
[lukas.bulwahn@gmail.com: remove debug code to removed CONFIG_CMA_DEBUG]
Link: https://lkml.kernel.org/r/20240207143825.986-1-lukas.bulwahn@gmail.com
Link: https://lkml.kernel.org/r/20240205031647.283510-1-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
After commit f7e01ab828 ("kasan: move tests to mm/kasan/"), the test
module file is renamed from lib/test_kasan_module.c to
mm/kasan/kasan_test_module.c, in order to keep consistent, rename
test_kasan_module_init to kasan_test_module_init.
Link: https://lkml.kernel.org/r/20240205060925.15594-3-yangtiezhu@loongson.cn
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Acked-by: Marco Elver <elver@google.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
After commit f7e01ab828 ("kasan: move tests to mm/kasan/"), the test
file is renamed to mm/kasan/kasan_test.c and the test module is renamed to
kasan_test.ko, so update the descriptions in the document.
While at it, update the line number and testcase number when the tests
kmalloc_large_oob_right and kmalloc_double_kzfree failed to sync with the
current code in mm/kasan/kasan_test.c.
Link: https://lkml.kernel.org/r/20240205060925.15594-2-yangtiezhu@loongson.cn
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Acked-by: Marco Elver <elver@google.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
hugetlb_madv_vs_map selftest was not part of the mm test-suite since we
didn't have a fix for the problem it found.
Now that the problem is already fixed (see previous commit), let's enable
this selftest in the default test-suite.
Link: https://lkml.kernel.org/r/20240205191843.4009640-3-leitao@debian.org
Signed-off-by: Breno Leitao <leitao@debian.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Rik van Riel <riel@surriel.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "mm/hugetlb: Restore the reservation", v2.
This is a fix for a case where a backing huge page could stolen after
madvise(MADV_DONTNEED).
A full reproducer is in selftest. See
https://lore.kernel.org/all/20240105155419.1939484-1-leitao@debian.org/
In order to test this patch, I instrumented the kernel with LOCKDEP and
KASAN, and run the following tests, without any regression:
* The self test that reproduces the problem
* All mm hugetlb selftests
SUMMARY: PASS=9 SKIP=0 FAIL=0
* All libhugetlbfs tests
PASS: 0 86
FAIL: 0 0
This patch (of 2):
Currently there is a bug that a huge page could be stolen, and when the
original owner tries to fault in it, it causes a page fault.
You can achieve that by:
1) Creating a single page
echo 1 > /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages
2) mmap() the page above with MAP_HUGETLB into (void *ptr1).
* This will mark the page as reserved
3) touch the page, which causes a page fault and allocates the page
* This will move the page out of the free list.
* It will also unreserved the page, since there is no more free
page
4) madvise(MADV_DONTNEED) the page
* This will free the page, but not mark it as reserved.
5) Allocate a secondary page with mmap(MAP_HUGETLB) into (void *ptr2).
* it should fail, but, since there is no more available page.
* But, since the page above is not reserved, this mmap() succeed.
6) Faulting at ptr1 will cause a SIGBUS
* it will try to allocate a huge page, but there is none
available
A full reproducer is in selftest. See
https://lore.kernel.org/all/20240105155419.1939484-1-leitao@debian.org/
Fix this by restoring the reserved page if necessary.
These are the condition for the page restore:
* The system is not using surplus pages. The goal is to reduce the
surplus usage for this case.
* If the VMA has the HPAGE_RESV_OWNER flag set, and is PRIVATE. This is
safely checked using __vma_private_lock()
* The page is anonymous
Once this is scenario is found, set the `hugetlb_restore_reserve` bit in
the folio. Then check if the resv reservations need to be adjusted
later, done later, after the spinlock, since the vma_xxxx_reservation()
might touch the file system lock.
Link: https://lkml.kernel.org/r/20240205191843.4009640-1-leitao@debian.org
Link: https://lkml.kernel.org/r/20240205191843.4009640-2-leitao@debian.org
Signed-off-by: Breno Leitao <leitao@debian.org>
Suggested-by: Rik van Riel <riel@surriel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Test that KASan can detect some unsafe atomic accesses.
As discussed in the linked thread below, these tests attempt to cover
the most common uses of atomics and, therefore, aren't exhaustive.
Link: https://lkml.kernel.org/r/20240202113259.3045705-1-paul.heidekrueger@tum.de
Link: https://lore.kernel.org/all/20240131210041.686657-1-paul.heidekrueger@tum.de/T/#u
Signed-off-by: Paul Heidekrüger <paul.heidekrueger@tum.de>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=214055
Acked-by: Mark Rutland <mark.rutland@arm.com>
Cc: Marco Elver <elver@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
"page_counter.h" does not need <linux/kernel.h>. <linux/limits.h> is enough
to get LONG_MAX.
Files that include page_counter.h are limited. They have been compile
tested or checked.
$ git grep page_counter\.h
include/linux/hugetlb_cgroup.h: struct page_counter hugepage[HUGE_MAX_HSTATE];
--> all files that include it have been compile tested
include/linux/memcontrol.h:#include <linux/page_counter.h>
--> <linux/kernel.h> has been added, to be safe
include/net/sock.h:#include <linux/page_counter.h>
--> already include <linux/kernel.h>
mm/hugetlb_cgroup.c:#include <linux/page_counter.h>
mm/memcontrol.c:#include <linux/page_counter.h>
mm/page_counter.c:#include <linux/page_counter.h>
--> compile tested
Link: https://lkml.kernel.org/r/adfdbe21c4d06400d7bd802868762deb85cae8b6.1706908921.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Before 388536ac291 ("mm:vmscan: fix inaccurate reclaim during proactive
reclaim") we passed the number of pages for the reclaim request directly
to try_to_free_mem_cgroup_pages, which could lead to significant
overreclaim. After 0388536ac2 the number of pages was limited to a
maximum 32 (SWAP_CLUSTER_MAX) to reduce the amount of overreclaim.
However such a small batch size caused a regression in reclaim performance
due to many more reclaim start/stop cycles inside memory_reclaim. The
restart cost is amortized over more pages with larger batch sizes, and
becomes a significant component of the runtime if the batch size is too
small.
Reclaim tries to balance nr_to_reclaim fidelity with fairness across nodes
and cgroups over which the pages are spread. As such, the bigger the
request, the bigger the absolute overreclaim error. Historic in-kernel
users of reclaim have used fixed, small sized requests to approach an
appropriate reclaim rate over time. When we reclaim a user request of
arbitrary size, use decaying batch sizes to manage error while maintaining
reasonable throughput.
MGLRU enabled - memcg LRU used
root - full reclaim pages/sec time (sec)
pre-0388536ac291 : 68047 10.46
post-0388536ac291 : 13742 inf
(reclaim-reclaimed)/4 : 67352 10.51
MGLRU enabled - memcg LRU not used
/uid_0 - 1G reclaim pages/sec time (sec) overreclaim (MiB)
pre-0388536ac291 : 258822 1.12 107.8
post-0388536ac291 : 105174 2.49 3.5
(reclaim-reclaimed)/4 : 233396 1.12 -7.4
MGLRU enabled - memcg LRU not used
/uid_0 - full reclaim pages/sec time (sec)
pre-0388536ac291 : 72334 7.09
post-0388536ac291 : 38105 14.45
(reclaim-reclaimed)/4 : 72914 6.96
[tjmercier@google.com: v4]
Link: https://lkml.kernel.org/r/20240206175251.3364296-1-tjmercier@google.com
Link: https://lkml.kernel.org/r/20240202233855.1236422-1-tjmercier@google.com
Fixes: 0388536ac2 ("mm:vmscan: fix inaccurate reclaim during proactive reclaim")
Signed-off-by: T.J. Mercier <tjmercier@google.com>
Reviewed-by: Yosry Ahmed <yosryahmed@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Michal Koutny <mkoutny@suse.com>
Acked-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Efly Young <yangyifei03@kuaishou.com>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
These vma_merge() callers will pass mm, anon_vma and file, they all from
the same vma. There is no need to pass three parameters at the same time.
Pass vma instead of mm, anon_vma and file to vma_merge(), so that it can
save two parameters.
Link: https://lkml.kernel.org/r/20240203014632.2726545-1-yajun.deng@linux.dev
Link: https://lore.kernel.org/lkml/20240125034922.1004671-2-yajun.deng@linux.dev/
Signed-off-by: Yajun Deng <yajun.deng@linux.dev>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Yajun Deng <yajun.deng@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The usage of run_vmtests.sh does not include hugetlb, which is a valid
test category.
Add the 'hugetlb' to the usage of run_vmtests.sh.
Link: https://lkml.kernel.org/r/20240129115246.1234253-1-leitao@debian.org
Signed-off-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Reviewed-by: Joel Savitz <jsavitz@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
... and conditionally return to the caller if any PTE except the first
one is writable. fork() has to make sure to properly write-protect in
case any PTE is writable. Other users (e.g., page unmaping) are expected
to not care.
Link: https://lkml.kernel.org/r/20240129124649.189745-16-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexandre Ghiti <alexghiti@rivosinc.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Naveen N. Rao <naveen.n.rao@linux.ibm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Russell King (Oracle) <linux@armlinux.org.uk>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Let's always ignore the accessed/young bit: we'll always mark the PTE as
old in our child process during fork, and upcoming users will similarly
not care.
Ignore the dirty bit only if we don't want to duplicate the dirty bit into
the child process during fork. Maybe, we could just set all PTEs in the
child dirty if any PTE is dirty. For now, let's keep the behavior
unchanged, this can be optimized later if required.
Ignore the soft-dirty bit only if the bit doesn't have any meaning in the
src vma, and similarly won't have any in the copied dst vma.
For now, we won't bother with the uffd-wp bit.
Link: https://lkml.kernel.org/r/20240129124649.189745-15-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexandre Ghiti <alexghiti@rivosinc.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Naveen N. Rao <naveen.n.rao@linux.ibm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Russell King (Oracle) <linux@armlinux.org.uk>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Let's implement PTE batching when consecutive (present) PTEs map
consecutive pages of the same large folio, and all other PTE bits besides
the PFNs are equal.
We will optimize folio_pte_batch() separately, to ignore selected PTE
bits. This patch is based on work by Ryan Roberts.
Use __always_inline for __copy_present_ptes() and keep the handling for
single PTEs completely separate from the multi-PTE case: we really want
the compiler to optimize for the single-PTE case with small folios, to not
degrade performance.
Note that PTE batching will never exceed a single page table and will
always stay within VMA boundaries.
Further, processing PTE-mapped THP that maybe pinned and have
PageAnonExclusive set on at least one subpage should work as expected, but
there is room for improvement: We will repeatedly (1) detect a PTE batch
(2) detect that we have to copy a page (3) fall back and allocate a single
page to copy a single page. For now we won't care as pinned pages are a
corner case, and we should rather look into maintaining only a single
PageAnonExclusive bit for large folios.
Link: https://lkml.kernel.org/r/20240129124649.189745-14-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
Reviewed-by: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexandre Ghiti <alexghiti@rivosinc.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Naveen N. Rao <naveen.n.rao@linux.ibm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Russell King (Oracle) <linux@armlinux.org.uk>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
