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There are no more multiple callers of __refill_stock(), so simply inline
it to refill_stock().
Link: https://lkml.kernel.org/r/20250404013913.1663035-5-shakeel.butt@linux.dev
Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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At multiple places in memcontrol.c, the memory and memsw page counters are
being uncharged. This is error-prone. Let's move the functionality to a
newly introduced memcg_uncharge and call it from all those places.
Link: https://lkml.kernel.org/r/20250404013913.1663035-4-shakeel.butt@linux.dev
Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Currently drain_obj_stock() can potentially call __refill_stock which
accesses local cpu stock and thus requires memcg stock's local_lock.
However if we look at the code paths leading to drain_obj_stock(), there
is never a good reason to refill the memcg stock at all from it.
At the moment, drain_obj_stock can be called from reclaim, hotplug cpu
teardown, mod_objcg_state() and refill_obj_stock(). For reclaim and
hotplug there is no need to refill. For the other two paths, most
probably the newly switched objcg would be used in near future and thus no
need to refill stock with the older objcg.
In addition, __refill_stock() from drain_obj_stock() happens on rare
cases, so performance is not really an issue. Let's just uncharge
directly instead of refill which will also decouple drain_obj_stock from
local cpu stock and local_lock requirements.
Link: https://lkml.kernel.org/r/20250404013913.1663035-3-shakeel.butt@linux.dev
Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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refill_stock can not be called with root memcg, so there is no need to
check it. Instead add a warning if root is ever passed to it.
Link: https://lkml.kernel.org/r/20250404013913.1663035-1-shakeel.butt@linux.dev
Link: https://lkml.kernel.org/r/20250404013913.1663035-2-shakeel.butt@linux.dev
Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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The vmalloc region can either be charged to a single memcg or none. At
the moment kernel traverses all the pages backing the vmalloc region to
update the MEMCG_VMALLOC stat. However there is no need to look at all
the pages as all those pages will be charged to a single memcg or none.
Simplify the MEMCG_VMALLOC update by just looking at the first page of the
vmalloc region.
[shakeel.butt@linux.dev: add comment]
Link: https://lkml.kernel.org/r/bmlkdbqgwboyqrnxyom7n52fjmo76ux77jhqw5odc6c6dfon3h@zdylwtmlywbt
Link: https://lkml.kernel.org/r/20250403053326.26860-1-shakeel.butt@linux.dev
Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Reviewed-by: Yosry Ahmed <yosry.ahmed@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Reduce the diff between low and high watermarks when compaction
proactiveness is set to high. This allows users who set the proactiveness
really high to have more stable fragmentation score over time.
Link: https://lkml.kernel.org/r/20250404111103.1994507-3-mclapinski@google.com
Signed-off-by: Michal Clapinski <mclapinski@google.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Patch series "mm/compaction: allow more aggressive proactive compaction",
v4.
Our goal is to keep memory usage of a VM low on the host. For that
reason, we use free page reporting which by default reports free pages of
order 9 and larger to the host to be freed. The feature works well only
if the memory in the guest is not fragmented below pages of order 9.
Proactive compaction can be reused to achieve defragmentation after some
parameter tweaking.
When the fragmentation score (lower is better) gets larger than the high
watermark, proactive compaction kicks in. Compaction stops when the score
goes below the low watermark (or no progress is made and backoff kicks
in). Let's define the difference between high and low watermarks as
leeway. Before these changes, the minimum possible value for low
watermark was 5 and the leeway was hardcoded to 10 (so minimum possible
value for high watermark was 15).
To test this, I created a VM with 19GB of memory and free page reporting
enabled. The VM was ~idle. I meassured the memory usage from inside the
guest (/proc/meminfo) and from the host (provided by the hypervisor).
Before:
https://drive.google.com/file/d/1Xw23lRry_PgEH3f6QRnSGvoHh2u9UHyI/view?usp=sharing
After:
https://drive.google.com/file/d/1wMhpIzepx6t44F70yCPA50n1S5V2AT-a/view?usp=sharing
This patch (of 2):
Previously a min cap of 5 has been set in the commit introducing proactive
compaction. This was to make sure users don't hurt themselves by setting
the proactiveness to 100 and making their system unresponsive. But the
compaction mechanism has a backoff mechanism that will sleep for 30s if no
progress is made, so I don't see a significant risk here. My system (19GB
of memory) has been perfectly fine with both watermarks hardcoded to 0.
Link: https://lkml.kernel.org/r/20250404111103.1994507-1-mclapinski@google.com
Link: https://lkml.kernel.org/r/20250404111103.1994507-2-mclapinski@google.com
Signed-off-by: Michal Clapinski <mclapinski@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Refactor free_page_is_bad() to call bad_page() directly, removing the
intermediate free_page_is_bad_report(). This reduces unnecessary
indirection, improving code clarity and maintainability without changing
functionality.
Link: https://lkml.kernel.org/r/20250328012031.1204993-1-ye.liu@linux.dev
Signed-off-by: Ye Liu <liuye@kylinos.cn>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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The writeback interface supports a page_index=N parameter which performs
writeback of the given page. Since we rarely need to writeback just one
single page, the typical use case involves a number of writeback calls,
each performing writeback of one page:
echo page_index=100 > zram0/writeback
...
echo page_index=200 > zram0/writeback
echo page_index=500 > zram0/writeback
...
echo page_index=700 > zram0/writeback
One obvious downside of this is that it increases the number of syscalls.
Less obvious, but a significantly more important downside, is that when
given only one page to post-process zram cannot perform an optimal target
selection. This becomes a critical limitation when writeback_limit is
enabled, because under writeback_limit we want to guarantee the highest
memory savings hence we first need to writeback pages that release the
highest amount of zsmalloc pool memory.
This patch adds page_indexes=LOW-HIGH parameter to the writeback
interface:
echo page_indexes=100-200 page_indexes=500-700 > zram0/writeback
This gives zram a chance to apply an optimal target selection strategy on
each iteration of the writeback loop.
We also now permit multiple page_index parameters per call (previously
zram would recognize only one page_index) and a mix or single pages and
page ranges:
echo page_index=42 page_index=99 page_indexes=100-200 \
page_indexes=500-700 > zram0/writeback
Apart from that the patch also unifies parameters passing and resembles
other "modern" zram device attributes (e.g. recompression), while the old
interface used a mixed scheme: values-less parameters for mode and a
key=value format for page_index. We still support the "old" value-less
format for compatibility reasons.
[senozhatsky@chromium.org: simplify parse_page_index() range checks, per Brian]
nk: https://lkml.kernel.org/r/20250404015327.2427684-1-senozhatsky@chromium.org
[sozhatsky@chromium.org: fix uninitialized variable in zram_writeback_slots(), per Dan]
nk: https://lkml.kernel.org/r/20250409112611.1154282-1-senozhatsky@chromium.org
Link: https://lkml.kernel.org/r/20250327015818.4148660-1-senozhatsky@chromium.org
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Reviewed-by: Brian Geffon <bgeffon@google.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Richard Chang <richardycc@google.com>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Cppcheck warning:
int result is assigned to long long variable. If the variable is long long
to avoid loss of information, then you have loss of information.
This patch changes the type of page_size from 'unsigned int' to
'unsigned long' instead of using ULL suffixes. Changing hpage_size to
'unsigned long' was considered, but since gethugepage() expects an int,
this change was avoided.
Link: https://lkml.kernel.org/r/20250403101345.29226-1-siddarthsgml@gmail.com
Signed-off-by: Siddarth G <siddarthsgml@gmail.com>
Reported-by: David Binderman <dcb314@hotmail.com>
Closes: https://lore.kernel.org/all/AS8PR02MB10217315060BBFDB21F19643E9CA62@AS8PR02MB10217.eurprd02.prod.outlook.com/
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Refactors the si_meminfo_node() function by reducing redundant code and
improving readability.
Moved the calculation of managed_pages inside the existing loop that
processes pgdat->node_zones, eliminating the need for a separate loop.
Simplified the logic by removing unnecessary preprocessor conditionals.
Ensured that both totalram, totalhigh, and other memory statistics are
consistently set without duplication.
This change results in cleaner and more efficient code without altering
functionality.
Link: https://lkml.kernel.org/r/20250325073803.852594-1-ye.liu@linux.dev
Signed-off-by: Ye Liu <liuye@kylinos.cn>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Harry Yoo <harry.yoo@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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mm_struct.hiwater_rss can be accessed concurrently without proper
synchronization as reported by KCSAN.
This data race is benign as it only affects accounting information.
Annotate it with data_race() to make KCSAN happy.
Link: https://lkml.kernel.org/r/20250331-mm-maxrss-data-race-v2-1-cf958e6205bf@iencinas.com
Signed-off-by: Ignacio Encinas <ignacio@iencinas.com>
Reported-by: syzbot+419c4b42acc36c420ad3@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/67e3390c.050a0220.1ec46.0001.GAE@google.com/
Suggested-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: Pedro Falcato <pfalcato@suse.de>
Cc: Liam Howlett <liam.howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Use a folio in the hugetlb pathway during the compaction migrate-able
pageblock scan.
This removes a call to compound_head().
Link: https://lkml.kernel.org/r/20250401021025.637333-2-vishal.moola@gmail.com
Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Acked-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Capacity is stranded when CFMWS regions are not aligned to block size. On
x86, block size increases with capacity (2G blocks @ 64G capacity).
Use CFMWS base/size to report memory block size alignment advice.
Link: https://lkml.kernel.org/r/20250127153405.3379117-4-gourry@gourry.net
Signed-off-by: Gregory Price <gourry@gourry.net>
Suggested-by: Dan Williams <dan.j.williams@intel.com>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Dan Williams <dan.j.williams@intel.com>
Tested-by: Fan Ni <fan.ni@samsung.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Acked-by: Oscar Salvador <osalvador@suse.de>
Cc: Alison Schofield <alison.schofield@intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Bruno Faccini <bfaccini@nvidia.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Haibo Xu <haibo1.xu@intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Joanthan Cameron <Jonathan.Cameron@huawei.com>
Cc: Len Brown <lenb@kernel.org>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Robert Richter <rrichter@amd.com>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Systems with hotplug may provide an advisement value on what the memblock
size should be. Probe this value when the rest of the configuration
values are considered.
The new heuristic is as follows
1) set_memory_block_size_order value if already set (cmdline param)
2) minimum block size if memory is less than large block limit
3) if no hotplug advice: Max block size if system is bare-metal,
otherwise use end of memory alignment.
4) if hotplug advice: lesser of advice and end of memory alignment.
Convert to cpu_feature_enabled() while at it.[1]
[1] https://lore.kernel.org/all/20241031103401.GBZyNdGQ-ZyXKyzC_z@fat_crate.local/
Link: https://lkml.kernel.org/r/20250127153405.3379117-3-gourry@gourry.net
Signed-off-by: Gregory Price <gourry@gourry.net>
Suggested-by: Borislav Petkov <bp@alien8.de>
Suggested-by: David Hildenbrand <david@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Acked-by: Dan Williams <dan.j.williams@intel.com>
Tested-by: Fan Ni <fan.ni@samsung.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Acked-by: Oscar Salvador <osalvador@suse.de>
Cc: Alison Schofield <alison.schofield@intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Bruno Faccini <bfaccini@nvidia.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Haibo Xu <haibo1.xu@intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Joanthan Cameron <Jonathan.Cameron@huawei.com>
Cc: Len Brown <lenb@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Robert Richter <rrichter@amd.com>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Patch series "memory,x86,acpi: hotplug memory alignment advisement", v8.
When physical address regions are not aligned to memory block size, the
misaligned portion is lost (stranded capacity).
Block size (min/max/selected) is architecture defined. Most architectures
tend to use the minimum block size or some simplistic heurist. On x86,
memory block size increases up to 2GB, and is otherwise fitted to the
alignment of non-hotplug (i.e. not special purpose memory).
CXL exposes its memory for management through the ACPI CEDT (CXL Early
Detection Table) in a field called the CXL Fixed Memory Window. Per the
CXL specification, this memory must be aligned to at least 256MB.
When a CFMW aligns on a size less than the block size, this causes a loss
of up to 2GB per CFMW on x86. It is not uncommon for CFMW to be allocated
per-device - though this behavior is BIOS defined.
This patch set provides 3 things:
1) implement advise/query functions in driverse/base/memory.c to
report/query architecture agnostic hotplug block alignment advice.
2) update x86 memblock size logic to consider the hotplug advice
3) add code in acpi/numa/srat.c to report CFMW alignment advice
The advisement interfaces are design to be called during arch_init code
prior to allocator and smp_init. start_kernel will call these through
setup_arch() (via acpi and mm/init_64.c on x86), which occurs prior to
mm_core_init and smp_init - so no need for atomics.
There's an attempt to signal callers to advise() that query has already
occurred, but this is predicated on the notion that query actually occurs
(which presently only happens on the x86 arch). This is to assist
debugging future users. Otherwise, the advise() call has been marked
__init to help static discovery of bad call times.
Once query is called the first time, it will always return the same value.
Interfaces return -EBUSY and 0 respectively on systems without hotplug.
This patch (of 3):
Hotplug memory sources may have opinions on what the memblock size should
be - usually for alignment purposes. For example, CXL memory extents can
be 256MB with a matching alignment. If this size/alignment is smaller
than the block size, it can result in stranded capacity.
Implement memory_block_advise_max_size for use prior to allocator init,
for software to advise the system on the max block size.
Implement memory_block_probe_max_size for use by arch init code to
calculate the best block size. Use of advice is architecture defined.
The probe value can never change after first probe. Calls to advise after
probe will return -EBUSY to aid debugging.
On systems without hotplug, always return -ENODEV and 0 respectively.
Link: https://lkml.kernel.org/r/20250127153405.3379117-1-gourry@gourry.net
Link: https://lkml.kernel.org/r/20250127153405.3379117-2-gourry@gourry.net
Signed-off-by: Gregory Price <gourry@gourry.net>
Suggested-by: Ira Weiny <ira.weiny@intel.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Acked-by: Dan Williams <dan.j.williams@intel.com>
Tested-by: Fan Ni <fan.ni@samsung.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Acked-by: Oscar Salvador <osalvador@suse.de>
Cc: Alison Schofield <alison.schofield@intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Bruno Faccini <bfaccini@nvidia.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Haibo Xu <haibo1.xu@intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Joanthan Cameron <Jonathan.Cameron@huawei.com>
Cc: Len Brown <lenb@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Robert Richter <rrichter@amd.com>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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In the current code, batch is a local variable, and it cannot be
concurrently modified. It's unnecessary to use READ_ONCE here, so remove
it.
Link: https://lkml.kernel.org/r/CAA=HWd1kn01ym8YuVFuAqK2Ggq3itEGkqX8T6eCXs_C7tiv-Jw@mail.gmail.com
Fixes: 51a755c56dc0 ("mm: tune PCP high automatically")
Signed-off-by: Songtang Liu <liusongtang@bytedance.com>
Reviewed-by: Qi Zheng <zhengqi.arch@bytedance.com>
Reviewed-by: Huang Ying <ying.huang@linux.alibaba.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Pankaj Gupta <pankaj.gupta@amd.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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7775face2079 ("memcg: killed threads should not invoke memcg OOM killer")
has added a bypass of the oom killer path for dying threads because a very
specific workload (described in the changelog) could hit "no killable
tasks" path. This itself is not fatal condition but it could be annoying
if this was a common case.
On the other hand the bypass has some issues on its own. Without
triggering oom killer we won't be able to trigger async oom reclaim
(oom_reaper) which can operate on killed tasks as well as long as they
still have their mm available. This could be the case during futex
cleanup when the memory as pointed out by Johannes in [1]. The said case
is still not fully understood but let's drop this bypass that was mostly
driven by an artificial workload and allow dying tasks to go into oom
path. This will make the code easier to reason about and also help corner
cases where oom_reaper could help to release memory.
Link: https://lore.kernel.org/all/20241212183012.GB1026@cmpxchg.org/T/#u [1]
Link: https://lkml.kernel.org/r/20250402090117.130245-1-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Rik van Riel <riel@surriel.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Currently, zsmalloc, zswap's and zram's backend memory allocator, does not
enforce any policy for the allocation of memory for the compressed data,
instead just adopting the memory policy of the task entering reclaim, or
the default policy (prefer local node) if no such policy is specified.
This can lead to several pathological behaviors in multi-node NUMA
systems:
1. Systems with CXL-based memory tiering can encounter the following
inversion with zswap/zram: the coldest pages demoted to the CXL tier
can return to the high tier when they are reclaimed to compressed swap,
creating memory pressure on the high tier.
2. Consider a direct reclaimer scanning nodes in order of allocation
preference. If it ventures into remote nodes, the memory it compresses
there should stay there. Trying to shift those contents over to the
reclaiming thread's preferred node further *increases* its local
pressure, and provoking more spills. The remote node is also the most
likely to refault this data again. This undesirable behavior was
pointed out by Johannes Weiner in [1].
3. For zswap writeback, the zswap entries are organized in
node-specific LRUs, based on the node placement of the original pages,
allowing for targeted zswap writeback for specific nodes.
However, the compressed data of a zswap entry can be placed on a
different node from the LRU it is placed on. This means that reclaim
targeted at one node might not free up memory used for zswap entries in
that node, but instead reclaiming memory in a different node.
All of these issues will be resolved if the compressed data go to the same
node as the original page. This patch encourages this behavior by having
zswap and zram pass the node of the original page to zsmalloc, and have
zsmalloc prefer the specified node if we need to allocate new (zs)pages
for the compressed data.
Note that we are not strictly binding the allocation to the preferred
node. We still allow the allocation to fall back to other nodes when the
preferred node is full, or if we have zspages with slots available on a
different node. This is OK, and still a strict improvement over the
status quo:
1. On a system with demotion enabled, we will generally prefer
demotions over compressed swapping, and only swap when pages have
already gone to the lowest tier. This patch should achieve the desired
effect for the most part.
2. If the preferred node is out of memory, letting the compressed data
going to other nodes can be better than the alternative (OOMs, keeping
cold memory unreclaimed, disk swapping, etc.).
3. If the allocation go to a separate node because we have a zspage
with slots available, at least we're not creating extra immediate
memory pressure (since the space is already allocated).
3. While there can be mixings, we generally reclaim pages in same-node
batches, which encourage zspage grouping that is more likely to go to
the right node.
4. A strict binding would require partitioning zsmalloc by node, which
is more complicated, and more prone to regression, since it reduces the
storage density of zsmalloc. We need to evaluate the tradeoff and
benchmark carefully before adopting such an involved solution.
[1]: https://lore.kernel.org/linux-mm/20250331165306.GC2110528@cmpxchg.org/
[senozhatsky@chromium.org: coding-style fixes]
Link: https://lkml.kernel.org/r/mnvexa7kseswglcqbhlot4zg3b3la2ypv2rimdl5mh5glbmhvz@wi6bgqn47hge
Link: https://lkml.kernel.org/r/20250402204416.3435994-1-nphamcs@gmail.com
Signed-off-by: Nhat Pham <nphamcs@gmail.com>
Suggested-by: Gregory Price <gourry@gourry.net>
Acked-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Chengming Zhou <chengming.zhou@linux.dev>
Acked-by: Sergey Senozhatsky <senozhatsky@chromium.org> [zram, zsmalloc]
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Yosry Ahmed <yosry.ahmed@linux.dev> [zswap/zsmalloc]
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Joanthan Cameron <Jonathan.Cameron@huawei.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
All callers now use folio_nr_pages(). Delete this wrapper.
Link: https://lkml.kernel.org/r/20250402210612.2444135-9-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
This function has no more callers; delete it.
Link: https://lkml.kernel.org/r/20250402210612.2444135-8-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Extract folios from i_mapping, not pages. Removes a hidden call to
compound_head(), a use of thp_nr_pages() and an unnecessary assertion that
we didn't find a tail page in the page cache.
Link: https://lkml.kernel.org/r/20250402210612.2444135-7-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
All users of this function now call folio_file_page() instead. Delete it.
Link: https://lkml.kernel.org/r/20250402210612.2444135-6-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
ITER_XARRAY is exclusively used with xarrays that contain folios, not
pages, so extract folio pointers from it, not page pointers. Removes a
use of find_subpage().
Link: https://lkml.kernel.org/r/20250402210612.2444135-5-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
ITER_XARRAY is exclusively used with xarrays that contain folios, not
pages, so extract folio pointers from it, not page pointers. Removes a
hidden call to compound_head() and a use of find_subpage().
Link: https://lkml.kernel.org/r/20250402210612.2444135-4-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
All callers have been converted to call offset_in_folio().
Link: https://lkml.kernel.org/r/20250402210612.2444135-3-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Patch series "Misc folio patches for 6.16".
Remove a few APIs that we've converted everybody from using. I also found
a few places that extract a page pointer from i_pages, which will be an
invalid thing to do when we separate pages from folios.
This patch (of 8):
All filesystems have now been converted to call readahead_folio() so we
can delete this wrapper.
Link: https://lkml.kernel.org/r/20250402210612.2444135-1-willy@infradead.org
Link: https://lkml.kernel.org/r/20250402210612.2444135-2-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
There are now no callers of mk_huge_pmd() and mk_pmd(). Remove them.
Link: https://lkml.kernel.org/r/20250402181709.2386022-12-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Richard Weinberger <richard@nod.at>
Cc: <x86@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Removes five conversions from folio to page. Also removes both callers of
mk_pmd() that aren't part of mk_huge_pmd(), getting us a step closer to
removing the confusion between mk_pmd(), mk_huge_pmd() and pmd_mkhuge().
Link: https://lkml.kernel.org/r/20250402181709.2386022-11-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Richard Weinberger <richard@nod.at>
Cc: <x86@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
The only remaining user of mk_huge_pte() is the debug code, so remove the
API and replace its use with pfn_pte() which lets us remove the conversion
to a page first. We should always call arch_make_huge_pte() to turn this
PTE into a huge PTE before operating on it with huge_pte_mkdirty() etc.
Link: https://lkml.kernel.org/r/20250402181709.2386022-10-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Richard Weinberger <richard@nod.at>
Cc: <x86@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
mk_huge_pte() is a bad API. Despite its name, it creates a normal PTE
which is later transformed into a huge PTE by arch_make_huge_pte(). So
replace the page argument with a folio argument and call folio_mk_pte()
instead. Then, because we now know this is a regular PTE rather than a
huge one, use pte_mkdirty() instead of huge_pte_mkdirty() (and similar
functions).
Link: https://lkml.kernel.org/r/20250402181709.2386022-9-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Richard Weinberger <richard@nod.at>
Cc: <x86@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Remove a cast from folio to page in four callers of mk_pte().
Link: https://lkml.kernel.org/r/20250402181709.2386022-8-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Richard Weinberger <richard@nod.at>
Cc: <x86@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
All architectures now use the common mk_pte() definition, so we can remove
the condition.
Link: https://lkml.kernel.org/r/20250402181709.2386022-7-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Richard Weinberger <richard@nod.at>
Cc: <x86@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Move the pfn_pte() definitions from the 2level and 4level files to the
generic pgtable.h and delete the custom definition of mk_pte() so that we
use the central definition.
Link: https://lkml.kernel.org/r/20250402181709.2386022-6-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: <x86@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Move the shadow stack check to pfn_pte() which lets us use the common
definition of mk_pte().
Link: https://lkml.kernel.org/r/20250402181709.2386022-5-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Richard Weinberger <richard@nod.at>
Cc: <x86@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Instead of defining pfn_pte() in terms of mk_pte(), make pfn_pte() the
base implementation. That lets us use the generic definition of mk_pte().
Link: https://lkml.kernel.org/r/20250402181709.2386022-4-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Zi Yan <ziy@nvidia.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Richard Weinberger <richard@nod.at>
Cc: <x86@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Most architectures simply call pfn_pte(). Centralise that as the normal
definition and remove the definition of mk_pte() from the architectures
which have either that exact definition or something similar.
Link: https://lkml.kernel.org/r/20250402181709.2386022-3-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> # m68k
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com> # s390
Cc: Zi Yan <ziy@nvidia.com>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Richard Weinberger <richard@nod.at>
Cc: <x86@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Patch series "Add folio_mk_pte()", v2.
Today if you have a folio and want to create a PTE that points to the
first page in it, you have to convert from a folio to a page. That's
zero-cost today but will be more expensive in the future.
I didn't want to add folio_mk_pte() to each architecture, and I didn't
want to lose any optimisations that architectures have from their own
implementation of mk_pte(). Fortunately, most architectures have by now
turned their mk_pte() into a fairly bland variant of pfn_pte(), but s390
has a special optimisation that needs to be moved into generic code in the
first patch.
At the end of this patch set, we have mk_pte() and folio_mk_pte() in mm.h
and each architecture only has to implement pfn_pte(). We've also
eliminated mk_huge_pte(), mk_huge_pmd() and mk_pmd().
This patch (of 11):
If the first access to a folio is a read that is then followed by a write,
we can save a page fault. s390 implemented this in their mk_pte() in
commit abf09bed3cce ("s390/mm: implement software dirty bits"), but other
architectures can also benefit from this.
Link: https://lkml.kernel.org/r/20250402181709.2386022-1-willy@infradead.org
Link: https://lkml.kernel.org/r/20250402181709.2386022-2-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com> # for s390
Cc: Zi Yan <ziy@nvidia.com>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Richard Weinberger <richard@nod.at>
Cc: <x86@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
In dirty_ratio_handler(), vm_dirty_bytes must be set to zero before
calling writeback_set_ratelimit(), as global_dirty_limits() always
prioritizes the value of vm_dirty_bytes.
It's domain_dirty_limits() that's relevant here, not node_dirty_ok:
dirty_ratio_handler
writeback_set_ratelimit
global_dirty_limits(&dirty_thresh) <- ratelimit_pages based on dirty_thresh
domain_dirty_limits
if (bytes) <- bytes = vm_dirty_bytes <--------+
thresh = f1(bytes) <- prioritizes vm_dirty_bytes |
else |
thresh = f2(ratio) |
ratelimit_pages = f3(dirty_thresh) |
vm_dirty_bytes = 0 <- it's late! ---------------------+
This causes ratelimit_pages to still use the value calculated based on
vm_dirty_bytes, which is wrong now.
The impact visible to userspace is difficult to capture directly because
there is no procfs/sysfs interface exported to user space. However, it
will have a real impact on the balance of dirty pages.
For example:
1. On default, we have vm_dirty_ratio=40, vm_dirty_bytes=0
2. echo 8192 > dirty_bytes, then vm_dirty_bytes=8192,
vm_dirty_ratio=0, and ratelimit_pages is calculated based on
vm_dirty_bytes now.
3. echo 20 > dirty_ratio, then since vm_dirty_bytes is not reset to
zero when writeback_set_ratelimit() -> global_dirty_limits() ->
domain_dirty_limits() is called, reallimit_pages is still calculated
based on vm_dirty_bytes instead of vm_dirty_ratio. This does not
conform to the actual intent of the user.
Link: https://lkml.kernel.org/r/20250415090232.7544-1-alexjlzheng@tencent.com
Fixes: 9d823e8f6b1b ("writeback: per task dirty rate limit")
Signed-off-by: Jinliang Zheng <alexjlzheng@tencent.com>
Reviewed-by: MengEn Sun <mengensun@tencent.com>
Cc: Andrea Righi <andrea@betterlinux.com>
Cc: Fenggaung Wu <fengguang.wu@intel.com>
Cc: Jinliang Zheng <alexjlzheng@tencent.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
merge mm-unstable's "mm: add folio_mk_pte()",
|
|
As David pointed out, what truly matters for mremap and userfaultfd move
operations is the soft dirty bit. The current comment and
implementation—which always sets the dirty bit for present PTEs and
fails to set the soft dirty bit for swap PTEs—are incorrect. This could
break features like Checkpoint-Restore in Userspace (CRIU).
This patch updates the behavior to correctly set the soft dirty bit for
both present and swap PTEs in accordance with mremap.
Link: https://lkml.kernel.org/r/20250508220912.7275-1-21cnbao@gmail.com
Fixes: adef440691ba ("userfaultfd: UFFDIO_MOVE uABI")
Signed-off-by: Barry Song <v-songbaohua@oppo.com>
Reported-by: David Hildenbrand <david@redhat.com>
Closes: https://lore.kernel.org/linux-mm/02f14ee1-923f-47e3-a994-4950afb9afcc@redhat.com/
Acked-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Cc: Lokesh Gidra <lokeshgidra@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Do not mix class->size and object size during offsets/sizes calculation in
zs_obj_write(). Size classes can merge into clusters, based on
objects-per-zspage and pages-per-zspage characteristics, so some size
classes can store objects smaller than class->size. This becomes
problematic when object size is much smaller than class->size. zsmalloc
can falsely decide that object spans two physical pages, because a larger
class->size value is used for that check, while the actual object is much
smaller and fits the free space of the first physical page, so there is
nothing to write to the second page and memcpy() size calculation
underflows.
Unable to handle kernel paging request at virtual address ffffc00081ff4000
pc : __memcpy+0x10/0x24
lr : zs_obj_write+0x1b0/0x1d0 [zsmalloc]
Call trace:
__memcpy+0x10/0x24 (P)
zram_write_page+0x150/0x4fc [zram]
zram_submit_bio+0x5e0/0x6a4 [zram]
__submit_bio+0x168/0x220
submit_bio_noacct_nocheck+0x128/0x2c8
submit_bio_noacct+0x19c/0x2f8
This is mostly seen on system with larger page-sizes, because size class
cluters of such systems hold wider size ranges than on 4K PAGE_SIZE
systems.
Assume a 16K PAGE_SIZE system, a write of 820 bytes object to a 864-bytes
size class at offset 15560. 15560 + 864 is more than 16384 so zsmalloc
attempts to memcpy() it to two physical pages. However, 16384 - 15560 =
824 which is more than 820, so the object in fact doesn't span two
physical pages, and there is no data to write to the second physical page.
We always know the exact size in bytes of the object that we are about to
write (store), so use it instead of class->size.
Link: https://lkml.kernel.org/r/20250507054312.4135983-1-senozhatsky@chromium.org
Fixes: 44f76413496e ("zsmalloc: introduce new object mapping API")
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Reported-by: Igor Belousov <igor.b@beldev.am>
Tested-by: Igor Belousov <igor.b@beldev.am>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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|
The page allocator tracks the number of zones that have unaccepted memory
using static_branch_enc/dec() and uses that static branch in hot paths to
determine if it needs to deal with unaccepted memory.
Borislav and Thomas pointed out that the tracking is racy: operations on
static_branch are not serialized against adding/removing unaccepted pages
to/from the zone.
Sanity checks inside static_branch machinery detects it:
WARNING: CPU: 0 PID: 10 at kernel/jump_label.c:276 __static_key_slow_dec_cpuslocked+0x8e/0xa0
The comment around the WARN() explains the problem:
/*
* Warn about the '-1' case though; since that means a
* decrement is concurrent with a first (0->1) increment. IOW
* people are trying to disable something that wasn't yet fully
* enabled. This suggests an ordering problem on the user side.
*/
The effect of this static_branch optimization is only visible on
microbenchmark.
Instead of adding more complexity around it, remove it altogether.
Link: https://lkml.kernel.org/r/20250506133207.1009676-1-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Fixes: dcdfdd40fa82 ("mm: Add support for unaccepted memory")
Link: https://lore.kernel.org/all/20250506092445.GBaBnVXXyvnazly6iF@fat_crate.local
Reported-by: Borislav Petkov <bp@alien8.de>
Tested-by: Borislav Petkov (AMD) <bp@alien8.de>
Reported-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: <stable@vger.kernel.org> [6.5+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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|
try_alloc_pages() will not attempt to allocate memory if the system has
*any* unaccepted memory. Memory is accepted as needed and can remain in
the system indefinitely, causing the interface to always fail.
Rather than immediately giving up, attempt to use already accepted memory
on free lists.
Pass 'alloc_flags' to cond_accept_memory() and do not accept new memory
for ALLOC_TRYLOCK requests.
Found via code inspection - only BPF uses this at present and the
runtime effects are unclear.
Link: https://lkml.kernel.org/r/20250506112509.905147-2-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Fixes: 97769a53f117 ("mm, bpf: Introduce try_alloc_pages() for opportunistic page allocation")
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
As part of the ongoing efforts to sub-divide memory management
maintainership and reviewership, establish a section for GUP (Get User
Pages) support and add appropriate maintainers and reviewers.
Link: https://lkml.kernel.org/r/20250506173601.97562-1-lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Commit 51ff4d7486f0 ("mm: avoid extra mem_alloc_profiling_enabled()
checks") introduces a possible use-after-free scenario, when page
is non-compound, page[0] could be released by other thread right
after put_page_testzero failed in current thread, pgalloc_tag_sub_pages
afterwards would manipulate an invalid page for accounting remaining
pages:
[timeline] [thread1] [thread2]
| alloc_page non-compound
V
| get_page, rf counter inc
V
| in ___free_pages
| put_page_testzero fails
V
| put_page, page released
V
| in ___free_pages,
| pgalloc_tag_sub_pages
| manipulate an invalid page
V
Restore __free_pages() to its state before, retrieve alloc tag
beforehand.
Link: https://lkml.kernel.org/r/20250505193034.91682-1-00107082@163.com
Fixes: 51ff4d7486f0 ("mm: avoid extra mem_alloc_profiling_enabled() checks")
Signed-off-by: David Wang <00107082@163.com>
Acked-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
The following WARNING was triggered during swap stress test with mTHP
enabled:
[ 6609.335758] ------------[ cut here ]------------
[ 6609.337758] WARNING: CPU: 82 PID: 755116 at mm/memory.c:3794 do_wp_page+0x1084/0x10e0
[ 6609.340922] Modules linked in: zram virtiofs
[ 6609.342699] CPU: 82 UID: 0 PID: 755116 Comm: sh Kdump: loaded Not tainted 6.15.0-rc1+ #1429 PREEMPT(voluntary)
[ 6609.347620] Hardware name: Red Hat KVM/RHEL-AV, BIOS 0.0.0 02/06/2015
[ 6609.349909] RIP: 0010:do_wp_page+0x1084/0x10e0
[ 6609.351532] Code: ff ff 48 c7 c6 80 ba 49 82 4c 89 ef e8 95 fd fe ff 0f 0b bd f5 ff ff ff e9 43 fb ff ff 41 83 a9 bc 12 00 00 01 e9 5c fb ff ff <0f> 0b e9 a6 fc ff ff 65 ff 00 f0 48 0f b
a 6d 00 1f 0f 83 82 fc ff
[ 6609.357959] RSP: 0000:ffffc90002273d40 EFLAGS: 00010287
[ 6609.359915] RAX: 000000000000000f RBX: 0000000000000000 RCX: 000fffffffe00000
[ 6609.362606] RDX: 0000000000000010 RSI: 000055a119ac1000 RDI: ffffea000ae6ec00
[ 6609.365143] RBP: ffffea000ae6ec68 R08: 84000002b9bb1025 R09: 000055a119ab6000
[ 6609.367569] R10: ffff8881caa2ad80 R11: 0000000000000000 R12: ffff8881caa2ad80
[ 6609.370255] R13: ffffea000ae6ec00 R14: 000055a119ac1c9c R15: ffffc90002273dd8
[ 6609.373007] FS: 00007f08e467f740(0000) GS:ffff88a07c214000(0000) knlGS:0000000000000000
[ 6609.375999] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 6609.377946] CR2: 000055a119ac1c9c CR3: 00000001adfd6005 CR4: 0000000000770eb0
[ 6609.380376] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 6609.382853] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 6609.385216] PKRU: 55555554
[ 6609.386141] Call Trace:
[ 6609.387017] <TASK>
[ 6609.387718] ? ___pte_offset_map+0x1b/0x110
[ 6609.389056] __handle_mm_fault+0xa51/0xf00
[ 6609.390363] ? exc_page_fault+0x6a/0x140
[ 6609.391629] handle_mm_fault+0x13d/0x360
[ 6609.392856] do_user_addr_fault+0x2f2/0x7f0
[ 6609.394160] ? sigprocmask+0x77/0xa0
[ 6609.395375] exc_page_fault+0x6a/0x140
[ 6609.396735] asm_exc_page_fault+0x26/0x30
[ 6609.398224] RIP: 0033:0x55a1050bc18b
[ 6609.399567] Code: 8b 3f 4d 85 ff 74 40 41 39 5f 18 75 f2 49 8b 7f 08 44 38 27 75 e9 4c 89 c6 4c 89 45 c8 e8 bd 83 fa ff 4c 8b 45 c8 85 c0 75 d5 <41> 83 47 1c 01 48 83 c4 28 4c 89 f8 5b 4
1 5c 41 5d 41 5e 41 5f 5d
[ 6609.405971] RSP: 002b:00007ffcf5f37d90 EFLAGS: 00010246
[ 6609.407737] RAX: 0000000000000000 RBX: 00000000182768fa RCX: 0000000000000000
[ 6609.410151] RDX: 00000000000000fa RSI: 000055a105175c7b RDI: 000055a119ac1c60
[ 6609.412606] RBP: 00007ffcf5f37de0 R08: 000055a105175c7b R09: 0000000000000000
[ 6609.414998] R10: 000000004d2dfb5a R11: 0000000000000246 R12: 0000000000000050
[ 6609.417193] R13: 00000000000000fa R14: 000055a119abaf60 R15: 000055a119ac1c80
[ 6609.419268] </TASK>
[ 6609.419928] ---[ end trace 0000000000000000 ]---
The WARN_ON here is simply incorrect. The refcount here must be at least
the mapcount, not the opposite. Each mapcount must have a corresponding
refcount, but the refcount may increase if other components grab the
folio, which is acceptable. Meanwhile, having a mapcount larger than
refcount is a real problem.
So fix the WARN_ON condition.
Link: https://lkml.kernel.org/r/20250425074325.61833-1-ryncsn@gmail.com
Fixes: 1da190f4d0a6 ("mm: Copy-on-Write (COW) reuse support for PTE-mapped THP")
Signed-off-by: Kairui Song <kasong@tencent.com>
Reported-by: Kairui Song <kasong@tencent.com>
Closes: https://lore.kernel.org/all/CAMgjq7D+ea3eg9gRCVvRnto3Sv3_H3WVhupX4e=k8T5QAfBHbw@mail.gmail.com/
Suggested-by: David Hildenbrand <david@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Not intuitive, but vm_area_dup() located in kernel/fork.c is not only used
for duplicating VMAs during fork(), but also for duplicating VMAs when
splitting VMAs or when mremap()'ing them.
VM_PFNMAP mappings can at least get ordinarily mremap()'ed (no change in
size) and apparently also shrunk during mremap(), which implies
duplicating the VMA in __split_vma() first.
In case of ordinary mremap() (no change in size), we first duplicate the
VMA in copy_vma_and_data()->copy_vma() to then call untrack_pfn_clear() on
the old VMA: we effectively move the VM_PAT reservation. So the
untrack_pfn_clear() call on the new VMA duplicating is wrong in that
context.
Splitting of VMAs seems problematic, because we don't duplicate/adjust the
reservation when splitting the VMA. Instead, in memtype_erase() -- called
during zapping/munmap -- we shrink a reservation in case only the end
address matches: Assume we split a VMA into A and B, both would share a
reservation until B is unmapped.
So when unmapping B, the reservation would be updated to cover only A.
When unmapping A, we would properly remove the now-shrunk reservation.
That scenario describes the mremap() shrinking (old_size > new_size),
where we split + unmap B, and the untrack_pfn_clear() on the new VMA when
is wrong.
What if we manage to split a VM_PFNMAP VMA into A and B and unmap A first?
It would be broken because we would never free the reservation. Likely,
there are ways to trigger such a VMA split outside of mremap().
Affecting other VMA duplication was not intended, vm_area_dup() being used
outside of kernel/fork.c was an oversight. So let's fix that for; how to
handle VMA splits better should be investigated separately.
With a simple reproducer that uses mprotect() to split such a VMA I can
trigger
x86/PAT: pat_mremap:26448 freeing invalid memtype [mem 0x00000000-0x00000fff]
Link: https://lkml.kernel.org/r/20250422144942.2871395-1-david@redhat.com
Fixes: dc84bc2aba85 ("x86/mm/pat: Fix VM_PAT handling when fork() fails in copy_page_range()")
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Rik van Riel <riel@surriel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
During our testing with hugetlb subpool enabled, we observe that
hstate->resv_huge_pages may underflow into negative values. Root cause
analysis reveals a race condition in subpool reservation fallback handling
as follow:
hugetlb_reserve_pages()
/* Attempt subpool reservation */
gbl_reserve = hugepage_subpool_get_pages(spool, chg);
/* Global reservation may fail after subpool allocation */
if (hugetlb_acct_memory(h, gbl_reserve) < 0)
goto out_put_pages;
out_put_pages:
/* This incorrectly restores reservation to subpool */
hugepage_subpool_put_pages(spool, chg);
When hugetlb_acct_memory() fails after subpool allocation, the current
implementation over-commits subpool reservations by returning the full
'chg' value instead of the actual allocated 'gbl_reserve' amount. This
discrepancy propagates to global reservations during subsequent releases,
eventually causing resv_huge_pages underflow.
This problem can be trigger easily with the following steps:
1. reverse hugepage for hugeltb allocation
2. mount hugetlbfs with min_size to enable hugetlb subpool
3. alloc hugepages with two task(make sure the second will fail due to
insufficient amount of hugepages)
4. with for a few seconds and repeat step 3 which will make
hstate->resv_huge_pages to go below zero.
To fix this problem, return corrent amount of pages to subpool during the
fallback after hugepage_subpool_get_pages is called.
Link: https://lkml.kernel.org/r/20250410062633.3102457-1-mawupeng1@huawei.com
Fixes: 1c5ecae3a93f ("hugetlbfs: add minimum size accounting to subpools")
Signed-off-by: Wupeng Ma <mawupeng1@huawei.com>
Tested-by: Joshua Hahn <joshua.hahnjy@gmail.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: David Hildenbrand <david@redhat.com>
Cc: Ma Wupeng <mawupeng1@huawei.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
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|
