- 22 Feb, 2024 23 commits
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Kefeng Wang authored
Call pfn_swap_entry_folio() in ptep_zap_swap_entry() as preparation for converting mm counter functions to take a folio. Link: https://lkml.kernel.org/r/20240111152429.3374566-5-willy@infradead.orgSigned-off-by:
Kefeng Wang <wangkefeng.wang@huawei.com> Signed-off-by:
Matthew Wilcox (Oracle) <willy@infradead.org> Cc: David Hildenbrand <david@redhat.com> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org>
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Matthew Wilcox (Oracle) authored
We only want to know whether the folio is anonymous, so use pfn_swap_entry_folio() and save a call to compound_head(). Link: https://lkml.kernel.org/r/20240111152429.3374566-4-willy@infradead.orgSigned-off-by:
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Matthew Wilcox (Oracle) authored
These callers only pass the result to PageAnon(), so we can save the extra call to compound_head() by using pfn_swap_entry_folio(). Link: https://lkml.kernel.org/r/20240111152429.3374566-3-willy@infradead.orgSigned-off-by:
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Matthew Wilcox (Oracle) authored
Patch series "mm: convert mm counter to take a folio", v3. Make sure all mm_counter() and mm_counter_file() callers have a folio, then convert mm counter functions to take a folio, which saves some compound_head() calls. This patch (of 10): Thanks to the compound_head() hidden inside PageLocked(), this saves a call to compound_head() over calling page_folio(pfn_swap_entry_to_page()) Link: https://lkml.kernel.org/r/20240111152429.3374566-1-willy@infradead.org Link: https://lkml.kernel.org/r/20240111152429.3374566-2-willy@infradead.orgSigned-off-by:
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Matthew Wilcox (Oracle) authored
Replace five calls to compound_head() with one. Link: https://lkml.kernel.org/r/20240111181219.3462852-5-willy@infradead.orgSigned-off-by:
Johannes Weiner <hannes@cmpxchg.org> Reviewed-by:
Roman Gushchin <roman.gushchin@linux.dev> Reviewed-by:
Muchun Song <muchun.song@linux.dev> Acked-by:
Shakeel Butt <shakeelb@google.com> Acked-by:
Michal Hocko <mhocko@suse.com> Signed-off-by:
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Matthew Wilcox (Oracle) authored
Replace seven calls to compound_head() with one. We still use the page as page_mapped() is different from folio_mapped(). Link: https://lkml.kernel.org/r/20240111181219.3462852-4-willy@infradead.orgSigned-off-by:
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Matthew Wilcox (Oracle) authored
All users of target.page convert it to the folio, so we can just return the folio directly and save a few calls to compound_head(). Link: https://lkml.kernel.org/r/20240111181219.3462852-3-willy@infradead.orgSigned-off-by:
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Matthew Wilcox (Oracle) authored
Patch series "Convert memcontrol charge moving to use folios". No part of these patches should change behaviour; all the called functions already convert from page to folio, so this ought to simply be a reduction in the number of calls to compound_head(). This patch (of 4): Remove many calls to compound_head() by calling page_folio() once at the start of each stanza which receives a struct page from 'target'. There should be no change in behaviour here as all the called functions start out by converting the page to its folio. Link: https://lkml.kernel.org/r/20240111181219.3462852-1-willy@infradead.org Link: https://lkml.kernel.org/r/20240111181219.3462852-2-willy@infradead.orgSigned-off-by:
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Yang Shi authored
We avoid allocating THP for temporary stack, even though khugepaged_enter_vma() is called for stack VMAs, it actualy returns false. So no need to call it in the first place at all. Link: https://lkml.kernel.org/r/20231221065943.2803551-1-shy828301@gmail.comSigned-off-by:
Yang Shi <yang@os.amperecomputing.com> Reviewed-by:
Yin Fengwei <fengwei.yin@intel.com> Cc: Christopher Lameter <cl@linux.com> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Rik van Riel <riel@surriel.com> Cc: kernel test robot <oliver.sang@intel.com> Signed-off-by:
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Haifeng Xu authored
list_lru_init_key() isn't used by anyone, remove it to clean up. Link: https://lkml.kernel.org/r/20231228062715.338672-2-haifeng.xu@shopee.comSigned-off-by:
Haifeng Xu <haifeng.xu@shopee.com> Acked-by:
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Haifeng Xu authored
Actually, when using a boot time kernel option "cgroup.memory=nokmem", all lru items are inserted to list_lru_node. But for those users who invoke list_lru_init_memcg() to initialize list_lru, list_lru_memcg_aware() returns true. And this brings unneeded operations related to memcg. To make things more convenient, let's disable memcg_aware when cgroup.memory is set to "nokmem". Link: https://lkml.kernel.org/r/20231228062715.338672-1-haifeng.xu@shopee.comSigned-off-by:
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Kefeng Wang authored
The clear and copy of huge gigantic page has converted to use nth_page() to handle the possible discontinuous struct page(SPARSEMEM without VMEMMAP), but not change for the non-gigantic part, fix it too. Link: https://lkml.kernel.org/r/20231229082207.60235-1-wangkefeng.wang@huawei.comSigned-off-by:
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Yajun Deng authored
The file parameter in the __remove_shared_vm_struct is no longer used, remove it. These functions vma_link() and mmap_region() have some of the same code, introduce vma_link_file() helper function to simplify the code. Link: https://lkml.kernel.org/r/20240110084622.2425927-1-yajun.deng@linux.devSigned-off-by:
Yajun Deng <yajun.deng@linux.dev> Signed-off-by:
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Kuan-Ying Lee authored
The patch series "Mitigate a vmap lock contention" removes vmap_area_list, which will break the gdb vmallocinfo command: (gdb) lx-vmallocinfo Python Exception <class 'gdb.error'>: No symbol "vmap_area_list" in current context. Error occurred in Python: No symbol "vmap_area_list" in current context. So we can instead use vmap_nodes to iterate all vmallocinfo. Link: https://lkml.kernel.org/r/20240207085856.11190-1-Kuan-Ying.Lee@mediatek.comSigned-off-by:
Kuan-Ying Lee <Kuan-Ying.Lee@mediatek.com> Cc: Casper Li <casper.li@mediatek.com> Cc: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> Cc: Chinwen Chang <chinwen.chang@mediatek.com> Cc: Jan Kiszka <jan.kiszka@siemens.com> Cc: Kieran Bingham <kbingham@kernel.org> Cc: Matthias Brugger <matthias.bgg@gmail.com> Cc: Qun-Wei Lin <qun-wei.lin@mediatek.com> Cc: Uladzislau Rezki (Sony) <urezki@gmail.com> Signed-off-by:
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JP Kobryn authored
Replace some goto statements with return statements so that unmap() is not called on an undefined address. This change is made so that unmap() can only be reached after mmap() is called (and the address mentioned is defined). Returning MAP_FAILED seems acceptable since client code checks for this value. Link: https://lkml.kernel.org/r/20240105202401.28851-1-inwardvessel@gmail.com Fixes: 42096aa2 ("selftest/mm: ksm_functional_tests: test in mmap_and_merge_range() if anything got merged") Signed-off-by:
JP Kobryn <inwardvessel@gmail.com> Reviewed-by:
David Hildenbrand <david@redhat.com> Signed-off-by:
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Hongbo Li authored
The return type of function folio_test_hugetlb is bool type, there is no need to assign it to an integer type. Link: https://lkml.kernel.org/r/20240108044815.3291487-1-lihongbo22@huawei.comSigned-off-by:
Hongbo Li <lihongbo22@huawei.com> Reviewed-by:
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Sumanth Korikkar authored
Enable MHP_MEMMAP_ON_MEMORY to support "memmap on memory". memory_hotplug.memmap_on_memory=true kernel parameter should be set in kernel boot option to enable the feature. Link: https://lkml.kernel.org/r/20240108132747.3238763-6-sumanthk@linux.ibm.comReviewed-by:
Gerald Schaefer <gerald.schaefer@linux.ibm.com> Signed-off-by:
Sumanth Korikkar <sumanthk@linux.ibm.com> Cc: Alexander Gordeev <agordeev@linux.ibm.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: David Hildenbrand <david@redhat.com> Cc: Heiko Carstens <hca@linux.ibm.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Signed-off-by:
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Sumanth Korikkar authored
MEM_PREPARE_ONLINE memory notifier makes memory block physical accessible via sclp assign command. The notifier ensures self-contained memory maps are accessible and hence enabling the "memmap on memory" on s390. MEM_FINISH_OFFLINE memory notifier shifts the memory block to an inaccessible state via sclp unassign command. Implementation considerations: * When MHP_MEMMAP_ON_MEMORY is disabled, the system retains the old behavior. This means the memory map is allocated from default memory. * If MACHINE_HAS_EDAT1 is unavailable, MHP_MEMMAP_ON_MEMORY is automatically disabled. This ensures that vmemmap pagetables do not consume additional memory from the default memory allocator. * The MEM_GOING_ONLINE notifier has been modified to perform no operation, as MEM_PREPARE_ONLINE already executes the sclp assign command. * The MEM_CANCEL_ONLINE/MEM_OFFLINE notifier now performs no operation, as MEM_FINISH_OFFLINE already executes the sclp unassign command. Link: https://lkml.kernel.org/r/20240108132747.3238763-5-sumanthk@linux.ibm.comReviewed-by:
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Sumanth Korikkar authored
Remove memory notifier types which are unhandled by s390. Unhandled memory notifier types are covered by default case. Link: https://lkml.kernel.org/r/20240108132747.3238763-4-sumanthk@linux.ibm.comSuggested-by:
Alexander Gordeev <agordeev@linux.ibm.com> Reviewed-by:
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Sumanth Korikkar authored
Allocate memory map (struct pages array) from the hotplugged memory range, rather than using system memory. The change addresses the issue where standby memory, when configured to be much larger than online memory, could potentially lead to ipl failure due to memory map allocation from online memory. For example, 16MB of memory map allocation is needed for a memory block size of 1GB and when standby memory is configured much larger than online memory, this could lead to ipl failure. To address this issue, the solution involves introducing "memmap on memory" using the vmem_altmap structure on s390. Architectures that want to implement it should pass the altmap to the vmemmap_populate() function and its associated callchain. This enhancement is discussed in commit 4b94ffdc ("x86, mm: introduce vmem_altmap to augment vmemmap_populate()") Provide "memmap on memory" support for s390 by passing the altmap in vmemmap_populate() and its callchain. The allocation path is described as follows: * When altmap is NULL in vmemmap_populate(), memory map allocation occurs using the existing vmemmap_alloc_block_buf(). * When altmap is not NULL in vmemmap_populate(), memory map allocation still uses vmemmap_alloc_block_buf(), but this function internally calls altmap_alloc_block_buf(). For deallocation, the process is outlined as follows: * When altmap is NULL in vmemmap_free(), memory map deallocation happens through free_pages(). * When altmap is not NULL in vmemmap_free(), memory map deallocation occurs via vmem_altmap_free(). While memory map allocation is primarily handled through the self-contained memory map range, there might still be a small amount of system memory allocation required for vmemmap pagetables. To mitigate this impact, this feature will be limited to machines with EDAT1 support. Link: https://lkml.kernel.org/r/20240108132747.3238763-3-sumanthk@linux.ibm.comReviewed-by:
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Sumanth Korikkar authored
Patch series "implement "memmap on memory" feature on s390". This series provides "memmap on memory" support on s390 platform. "memmap on memory" allows struct pages array to be allocated from the hotplugged memory range instead of allocating it from main system memory. s390 currently preallocates struct pages array for all potentially possible memory, which ensures memory onlining always succeeds, but with the cost of significant memory consumption from the available system memory during boottime. In certain extreme configuration, this could lead to ipl failure. "memmap on memory" ensures struct pages array are populated from self contained hotplugged memory range instead of depleting the available system memory and this could eliminate ipl failure on s390 platform. On other platforms, system might go OOM when the physically hotplugged memory depletes the available memory before it is onlined. Hence, "memmap on memory" feature was introduced as described in commit a08a2ae3 ("mm,memory_hotplug: allocate memmap from the added memory range"). Unlike other architectures, s390 memory blocks are not physically accessible until it is online. To make it physically accessible two new memory notifiers MEM_PREPARE_ONLINE / MEM_FINISH_OFFLINE are added and this notifier lets the hypervisor inform that the memory should be made physically accessible. This allows for "memmap on memory" initialization during memory hotplug onlining phase, which is performed before calling MEM_GOING_ONLINE notifier. Patch 1 introduces MEM_PREPARE_ONLINE/MEM_FINISH_OFFLINE memory notifiers to prepare the transition of memory to and from a physically accessible state. New mhp_flag MHP_OFFLINE_INACCESSIBLE is introduced to ensure altmap cannot be written when adding memory - before it is set online. This enhancement is crucial for implementing the "memmap on memory" feature for s390 in a subsequent patch. Patches 2 allocates vmemmap pages from self-contained memory range for s390. It allocates memory map (struct pages array) from the hotplugged memory range, rather than using system memory by passing altmap to vmemmap functions. Patch 3 removes unhandled memory notifier types on s390. Patch 4 implements MEM_PREPARE_ONLINE/MEM_FINISH_OFFLINE memory notifiers on s390. MEM_PREPARE_ONLINE memory notifier makes memory block physical accessible via sclp assign command. The notifier ensures self-contained memory maps are accessible and hence enabling the "memmap on memory" on s390. MEM_FINISH_OFFLINE memory notifier shifts the memory block to an inaccessible state via sclp unassign command. Patch 5 finally enables MHP_MEMMAP_ON_MEMORY on s390. This patch (of 5): Introduce MEM_PREPARE_ONLINE/MEM_FINISH_OFFLINE memory notifiers to prepare the transition of memory to and from a physically accessible state. This enhancement is crucial for implementing the "memmap on memory" feature for s390 in a subsequent patch. Platforms such as x86 can support physical memory hotplug via ACPI. When there is physical memory hotplug, ACPI event leads to the memory addition with the following callchain: acpi_memory_device_add() -> acpi_memory_enable_device() -> __add_memory() After this, the hotplugged memory is physically accessible, and altmap support prepared, before the "memmap on memory" initialization in memory_block_online() is called. On s390, memory hotplug works in a different way. The available hotplug memory has to be defined upfront in the hypervisor, but it is made physically accessible only when the user sets it online via sysfs, currently in the MEM_GOING_ONLINE notifier. This is too late and "memmap on memory" initialization is performed before calling MEM_GOING_ONLINE notifier. During the memory hotplug addition phase, altmap support is prepared and during the memory onlining phase s390 requires memory to be physically accessible and then subsequently initiate the "memmap on memory" initialization process. The memory provider will handle new MEM_PREPARE_ONLINE / MEM_FINISH_OFFLINE notifications and make the memory accessible. The mhp_flag MHP_OFFLINE_INACCESSIBLE is introduced and is relevant when used along with MHP_MEMMAP_ON_MEMORY, because the altmap cannot be written (e.g., poisoned) when adding memory -- before it is set online. This allows for adding memory with an altmap that is not currently made available by a hypervisor. When onlining that memory, the hypervisor can be instructed to make that memory accessible via the new notifiers and the onlining phase will not require any memory allocations, which is helpful in low-memory situations. All architectures ignore unknown memory notifiers. Therefore, the introduction of these new notifiers does not result in any functional modifications across architectures. Link: https://lkml.kernel.org/r/20240108132747.3238763-1-sumanthk@linux.ibm.com Link: https://lkml.kernel.org/r/20240108132747.3238763-2-sumanthk@linux.ibm.comSigned-off-by:
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Sidhartha Kumar authored
The function description comment for mas_node_count_gfp() mistakingly refers to the function as mas_node_count(). Change it to refer to the correct function. Link: https://lkml.kernel.org/r/20240109223119.162357-1-sidhartha.kumar@oracle.comSigned-off-by:
Sidhartha Kumar <sidhartha.kumar@oracle.com> Reviewed-by:
Liam R. Howlett <Liam.Howlett@oracle.com> Cc: Peng Zhang <zhangpeng.00@bytedance.com> Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com> Signed-off-by:
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Kalesh Singh authored
The current placement of trace_cma_alloc_start/finish misses the fail cases: !cma || !cma->count || !cma->bitmap. trace_cma_alloc_finish is also not emitted for the failure case where bitmap_count > bitmap_maxno. Fix these missed cases by moving the start event before the failure checks and moving the finish event to the out label. Link: https://lkml.kernel.org/r/20240110012234.3793639-1-kaleshsingh@google.com Fixes: 7bc1aec5 ("mm: cma: add trace events for CMA alloc perf testing") Signed-off-by:
Kalesh Singh <kaleshsingh@google.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Liam Mark <lmark@codeaurora.org> Signed-off-by:
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- 20 Feb, 2024 14 commits
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Benjamin Gray authored
release_free_meta() accesses the shadow directly through the path kasan_slab_free __kasan_slab_free kasan_release_object_meta release_free_meta kasan_mem_to_shadow There are no kasan_arch_is_ready() guards here, allowing an oops when the shadow is not initialized. The oops can be seen on a Power8 KVM guest. This patch adds the guard to release_free_meta(), as it's the first level that specifically requires the shadow. It is safe to put the guard at the start of this function, before the stack put: only kasan_save_free_info() can initialize the saved stack, which itself is guarded with kasan_arch_is_ready() by its caller poison_slab_object(). If the arch becomes ready before release_free_meta() then we will not observe KASAN_SLAB_FREE_META in the object's shadow, so we will not put an uninitialized stack either. Link: https://lkml.kernel.org/r/20240213033958.139383-1-bgray@linux.ibm.com Fixes: 63b85ac5 ("kasan: stop leaking stack trace handles") Signed-off-by:Benjamin Gray <bgray@linux.ibm.com> Reviewed-by:
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: Michael Ellerman <mpe@ellerman.id.au> Cc: Vincenzo Frascino <vincenzo.frascino@arm.com> Signed-off-by:
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SeongJae Park authored
For online parameters change, DAMON_LRU_SORT creates new schemes based on latest values of the parameters and replaces the old schemes with the new one. When creating it, the internal status of the quotas of the old schemes is not preserved. As a result, charging of the quota starts from zero after the online tuning. The data that collected to estimate the throughput of the scheme's action is also reset, and therefore the estimation should start from the scratch again. Because the throughput estimation is being used to convert the time quota to the effective size quota, this could result in temporal time quota inaccuracy. It would be recovered over time, though. In short, the quota accuracy could be temporarily degraded after online parameters update. Fix the problem by checking the case and copying the internal fields for the status. Link: https://lkml.kernel.org/r/20240216194025.9207-3-sj@kernel.org Fixes: 40e983cc ("mm/damon: introduce DAMON-based LRU-lists Sorting") Signed-off-by:
SeongJae Park <sj@kernel.org> Cc: <stable@vger.kernel.org> [6.0+] Signed-off-by:
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SeongJae Park authored
Patch series "mm/damon: fix quota status loss due to online tunings". DAMON_RECLAIM and DAMON_LRU_SORT is not preserving internal quota status when applying new user parameters, and hence could cause temporal quota accuracy degradation. Fix it by preserving the status. This patch (of 2): For online parameters change, DAMON_RECLAIM creates new scheme based on latest values of the parameters and replaces the old scheme with the new one. When creating it, the internal status of the quota of the old scheme is not preserved. As a result, charging of the quota starts from zero after the online tuning. The data that collected to estimate the throughput of the scheme's action is also reset, and therefore the estimation should start from the scratch again. Because the throughput estimation is being used to convert the time quota to the effective size quota, this could result in temporal time quota inaccuracy. It would be recovered over time, though. In short, the quota accuracy could be temporarily degraded after online parameters update. Fix the problem by checking the case and copying the internal fields for the status. Link: https://lkml.kernel.org/r/20240216194025.9207-1-sj@kernel.org Link: https://lkml.kernel.org/r/20240216194025.9207-2-sj@kernel.org Fixes: e035c280 ("mm/damon/reclaim: support online inputs update") Signed-off-by:
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Shakeel Butt authored
Moving to linux.dev based email for kernel work. Link: https://lkml.kernel.org/r/20240219205050.887810-1-shakeel.butt@linux.devSigned-off-by:
Shakeel Butt <shakeel.butt@linux.dev> Signed-off-by:
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SeongJae Park authored
'commit_schemes_quota_goals' command handler, damos_sysfs_set_quota_scores() assumes the number of schemes sysfs directory will be same to the number of schemes of the DAMON context. The assumption is wrong since users can remove schemes sysfs directories while DAMON is running. In the case, illegal memory accesses can happen. Fix it by checking the case. Link: https://lkml.kernel.org/r/20240213023633.124928-1-sj@kernel.org Fixes: d91beaa5 ("mm/damon/sysfs-schemes: implement a command for scheme quota goals only commit") Signed-off-by:
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Johannes Weiner authored
The swapaccount deprecation warning is throwing false positives. Since we deprecated the knob and defaulted to enabling, the only reports we've been getting are from folks that set swapaccount=1. While this is a nice affirmation that always-enabling was the right choice, we certainly don't want to warn when users request the supported mode. Only warn when disabling is requested, and clarify the warning. [colin.i.king@gmail.com: spelling: "commdandline" -> "commandline"] Link: https://lkml.kernel.org/r/20240215090544.1649201-1-colin.i.king@gmail.com Link: https://lkml.kernel.org/r/20240213081634.3652326-1-hannes@cmpxchg.org Fixes: b25806dc ("mm: memcontrol: deprecate swapaccounting=0 mode") Signed-off-by:
Colin Ian King <colin.i.king@gmail.com> Reported-by:
"Jonas Schäfer" <jonas@wielicki.name> Reported-by:
Narcis Garcia <debianlists@actiu.net> Suggested-by:
Yosry Ahmed <yosryahmed@google.com> Signed-off-by:
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Anshuman Khandual authored
The commit 77e6c43e ("memblock: introduce MEMBLOCK_RSRV_NOINIT flag") skipped adding this newly introduced memblock flag into flagname[] array, thus preventing a correct memblock flags output for applicable memblock regions. Link: https://lkml.kernel.org/r/20240209030912.1382251-1-anshuman.khandual@arm.com Fixes: 77e6c43e ("memblock: introduce MEMBLOCK_RSRV_NOINIT flag") Signed-off-by:
Anshuman Khandual <anshuman.khandual@arm.com> Reviewed-by:
Mike Rapoport <rppt@kernel.org> Cc: <stable@vger.kernel.org> Signed-off-by:
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Chengming Zhou authored
We have to invalidate any duplicate entry even when !zswap_enabled since zswap can be disabled anytime. If the folio store success before, then got dirtied again but zswap disabled, we won't invalidate the old duplicate entry in the zswap_store(). So later lru writeback may overwrite the new data in swapfile. Link: https://lkml.kernel.org/r/20240208023254.3873823-1-chengming.zhou@linux.dev Fixes: 42c06a0e ("mm: kill frontswap") Signed-off-by:
Chengming Zhou <zhouchengming@bytedance.com> Acked-by:
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Guenter Roeck authored
Trying to run the iov_iter unit test on a nommu system such as the qemu kc705-nommu emulation results in a crash. KTAP version 1 # Subtest: iov_iter # module: kunit_iov_iter 1..9 BUG: failure at mm/nommu.c:318/vmap()! Kernel panic - not syncing: BUG! The test calls vmap() directly, but vmap() is not supported on nommu systems, causing the crash. TEST_IOV_ITER therefore needs to depend on MMU. Link: https://lkml.kernel.org/r/20240208153010.1439753-1-linux@roeck-us.net Fixes: 2d71340f ("iov_iter: Kunit tests for copying to/from an iterator") Signed-off-by:Guenter Roeck <linux@roeck-us.net> Cc: David Howells <dhowells@redhat.com> Cc: <stable@vger.kernel.org> Signed-off-by:
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Kairui Song authored
When skipping swapcache for SWP_SYNCHRONOUS_IO, if two or more threads swapin the same entry at the same time, they get different pages (A, B). Before one thread (T0) finishes the swapin and installs page (A) to the PTE, another thread (T1) could finish swapin of page (B), swap_free the entry, then swap out the possibly modified page reusing the same entry. It breaks the pte_same check in (T0) because PTE value is unchanged, causing ABA problem. Thread (T0) will install a stalled page (A) into the PTE and cause data corruption. One possible callstack is like this: CPU0 CPU1 ---- ---- do_swap_page() do_swap_page() with same entry <direct swapin path> <direct swapin path> <alloc page A> <alloc page B> swap_read_folio() <- read to page A swap_read_folio() <- read to page B <slow on later locks or interrupt> <finished swapin first> ... set_pte_at() swap_free() <- entry is free <write to page B, now page A stalled> <swap out page B to same swap entry> pte_same() <- Check pass, PTE seems unchanged, but page A is stalled! swap_free() <- page B content lost! set_pte_at() <- staled page A installed! And besides, for ZRAM, swap_free() allows the swap device to discard the entry content, so even if page (B) is not modified, if swap_read_folio() on CPU0 happens later than swap_free() on CPU1, it may also cause data loss. To fix this, reuse swapcache_prepare which will pin the swap entry using the cache flag, and allow only one thread to swap it in, also prevent any parallel code from putting the entry in the cache. Release the pin after PT unlocked. Racers just loop and wait since it's a rare and very short event. A schedule_timeout_uninterruptible(1) call is added to avoid repeated page faults wasting too much CPU, causing livelock or adding too much noise to perf statistics. A similar livelock issue was described in commit 029c4628 ("mm: swap: get rid of livelock in swapin readahead") Reproducer: This race issue can be triggered easily using a well constructed reproducer and patched brd (with a delay in read path) [1]: With latest 6.8 mainline, race caused data loss can be observed easily: $ gcc -g -lpthread test-thread-swap-race.c && ./a.out Polulating 32MB of memory region... Keep swapping out... Starting round 0... Spawning 65536 workers... 32746 workers spawned, wait for done... Round 0: Error on 0x5aa00, expected 32746, got 32743, 3 data loss! Round 0: Error on 0x395200, expected 32746, got 32743, 3 data loss! Round 0: Error on 0x3fd000, expected 32746, got 32737, 9 data loss! Round 0 Failed, 15 data loss! This reproducer spawns multiple threads sharing the same memory region using a small swap device. Every two threads updates mapped pages one by one in opposite direction trying to create a race, with one dedicated thread keep swapping out the data out using madvise. The reproducer created a reproduce rate of about once every 5 minutes, so the race should be totally possible in production. After this patch, I ran the reproducer for over a few hundred rounds and no data loss observed. Performance overhead is minimal, microbenchmark swapin 10G from 32G zram: Before: 10934698 us After: 11157121 us Cached: 13155355 us (Dropping SWP_SYNCHRONOUS_IO flag) [kasong@tencent.com: v4] Link: https://lkml.kernel.org/r/20240219082040.7495-1-ryncsn@gmail.com Link: https://lkml.kernel.org/r/20240206182559.32264-1-ryncsn@gmail.com Fixes: 0bcac06f ("mm, swap: skip swapcache for swapin of synchronous device") Reported-by:"Huang, Ying" <ying.huang@intel.com> Closes: https://lore.kernel.org/lkml/87bk92gqpx.fsf_-_@yhuang6-desk2.ccr.corp.intel.com/ Link: https://github.com/ryncsn/emm-test-project/tree/master/swap-stress-race [1] Signed-off-by:
Kairui Song <kasong@tencent.com> Reviewed-by:
Yu Zhao <yuzhao@google.com> Acked-by:
Chris Li <chrisl@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Yosry Ahmed <yosryahmed@google.com> Cc: Yu Zhao <yuzhao@google.com> Cc: Barry Song <21cnbao@gmail.com> Cc: SeongJae Park <sj@kernel.org> Cc: <stable@vger.kernel.org> Signed-off-by:
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Nhat Pham authored
When a folio is swapped in, the protection size of the corresponding zswap LRU is incremented, so that the zswap shrinker is more conservative with its reclaiming action. This field is embedded within the struct lruvec, so updating it requires looking up the folio's memcg and lruvec. However, currently this lookup can happen after the folio is unlocked, for instance if a new folio is allocated, and swap_read_folio() unlocks the folio before returning. In this scenario, there is no stability guarantee for the binding between a folio and its memcg and lruvec: * A folio's memcg and lruvec can be freed between the lookup and the update, leading to a UAF. * Folio migration can clear the now-unlocked folio's memcg_data, which directs the zswap LRU protection size update towards the root memcg instead of the original memcg. This was recently picked up by the syzbot thanks to a warning in the inlined folio_lruvec() call. Move the zswap LRU protection range update above the swap_read_folio() call, and only when a new page is allocated, to prevent this. [nphamcs@gmail.com: add VM_WARN_ON_ONCE() to zswap_folio_swapin()] Link: https://lkml.kernel.org/r/20240206180855.3987204-1-nphamcs@gmail.com [nphamcs@gmail.com: remove unneeded if (folio) checks] Link: https://lkml.kernel.org/r/20240206191355.83755-1-nphamcs@gmail.com Link: https://lkml.kernel.org/r/20240205232442.3240571-1-nphamcs@gmail.com Fixes: b5ba474f ("zswap: shrink zswap pool based on memory pressure") Reported-by: syzbot+17a611d10af7d18a7092@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/000000000000ae47f90610803260@google.com/Signed-off-by:
Nhat Pham <nphamcs@gmail.com> Reviewed-by:
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Terry Tritton authored
If HUGETLBFS is not enabled then the default_huge_page_size function will return 0 and cause a divide by 0 error. Add a check to see if the huge page size is 0 and skip the hugetlb tests if it is. Link: https://lkml.kernel.org/r/20240205145055.3545806-2-terry.tritton@linaro.org Fixes: 16a45b57 ("selftests/mm: add framework for uffd-unit-test") Signed-off-by:
Terry Tritton <terry.tritton@linaro.org> Cc: Peter Griffin <peter.griffin@linaro.org> Cc: Shuah Khan <shuah@kernel.org> Cc: Peter Xu <peterx@redhat.com> Cc: <stable@vger.kernel.org> Signed-off-by:
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SeongJae Park authored
kdamond_apply_schemes() checks apply intervals of schemes and avoid further applying any schemes if no scheme passed its apply interval. However, the following schemes applying function, damon_do_apply_schemes() iterates all schemes without the apply interval check. As a result, the shortest apply interval is applied to all schemes. Fix the problem by checking the apply interval in damon_do_apply_schemes(). Link: https://lkml.kernel.org/r/20240205201306.88562-1-sj@kernel.org Fixes: 42f994b7 ("mm/damon/core: implement scheme-specific apply interval") Signed-off-by:
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Yosry Ahmed authored
In zswap_writeback_entry(), after we get a folio from __read_swap_cache_async(), we grab the tree lock again to check that the swap entry was not invalidated and recycled. If it was, we delete the folio we just added to the swap cache and exit. However, __read_swap_cache_async() returns the folio locked when it is newly allocated, which is always true for this path, and the folio is ref'd. Make sure to unlock and put the folio before returning. This was discovered by code inspection, probably because this path handles a race condition that should not happen often, and the bug would not crash the system, it will only strand the folio indefinitely. Link: https://lkml.kernel.org/r/20240125085127.1327013-1-yosryahmed@google.com Fixes: 04fc7816 ("mm: fix zswap writeback race condition") Signed-off-by:
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- 18 Feb, 2024 3 commits
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Linus Torvalds authored
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Linus Torvalds authored
Merge tag 'kbuild-fixes-v6.8-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild Pull Kbuild fixes from Masahiro Yamada: - Reformat nested if-conditionals in Makefiles with 4 spaces - Fix CONFIG_DEBUG_INFO_BTF builds for big endian - Fix modpost for module srcversion - Fix an escape sequence warning in gen_compile_commands.py - Fix kallsyms to ignore ARMv4 thunk symbols * tag 'kbuild-fixes-v6.8-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: kallsyms: ignore ARMv4 thunks along with others modpost: trim leading spaces when processing source files list gen_compile_commands: fix invalid escape sequence warning kbuild: Fix changing ELF file type for output of gen_btf for big endian docs: kconfig: Fix grammar and formatting kbuild: use 4-space indentation when followed by conditionals
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tipLinus Torvalds authored
Pull x86 fix from Borislav Petkov: - Use a GB page for identity mapping only when memory of this size is requested so that mapping of reserved regions is prevented which would otherwise lead to system crashes on UV machines * tag 'x86_urgent_for_v6.8_rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/mm/ident_map: Use gbpages only where full GB page should be mapped.
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