kernel/linux.git/Documentation/admin-guide/mm, branch v6.12.80

mm: fix docs for the kernel parameter ``thp_anon=``

2024-11-07T22:14:59+00:00

If we add ``thp_anon=32,64K:always`` to the kernel command line, we will see the following error: [ 0.000000] huge_memory: thp_anon=32,64K:always: error parsing string, ignoring setting This happens because the correct format isn't ``thp_anon=,[KMG]:```, as [KMG] must follow each number to especify its unit. So, the correct format is ``thp_anon=[KMG],[KMG]:```. Therefore, adjust the documentation to reflect the correct format of the parameter ``thp_anon=``. Link: https://lkml.kernel.org/r/20241101165719.1074234-3-mcanal@igalia.com Fixes: dd4d30d1cdbe ("mm: override mTHP "enabled" defaults at kernel cmdline") Signed-off-by: Maíra Canal Acked-by: Barry Song Acked-by: David Hildenbrand Cc: Baolin Wang Cc: Hugh Dickins Cc: Jonathan Corbet Cc: Lance Yang Cc: Ryan Roberts Signed-off-by: Andrew Morton

Merge tag 'mm-nonmm-stable-2024-09-21-07-52' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2024-09-21T15:20:50+00:00

Pull non-MM updates from Andrew Morton: "Many singleton patches - please see the various changelogs for details. Quite a lot of nilfs2 work this time around. Notable patch series in this pull request are: - "mul_u64_u64_div_u64: new implementation" by Nicolas Pitre, with assistance from Uwe Kleine-König. Reimplement mul_u64_u64_div_u64() to provide (much) more accurate results. The current implementation was causing Uwe some issues in the PWM drivers. - "xz: Updates to license, filters, and compression options" from Lasse Collin. Miscellaneous maintenance and kinor feature work to the xz decompressor. - "Fix some GDB command error and add some GDB commands" from Kuan-Ying Lee. Fixes and enhancements to the gdb scripts. - "treewide: add missing MODULE_DESCRIPTION() macros" from Jeff Johnson. Adds lots of MODULE_DESCRIPTIONs, thus fixing lots of warnings about this. - "nilfs2: add support for some common ioctls" from Ryusuke Konishi. Adds various commonly-available ioctls to nilfs2. - "This series fixes a number of formatting issues in kernel doc comments" from Ryusuke Konishi does that. - "nilfs2: prevent unexpected ENOENT propagation" from Ryusuke Konishi. Fix issues where -ENOENT was being unintentionally and inappropriately returned to userspace. - "nilfs2: assorted cleanups" from Huang Xiaojia. - "nilfs2: fix potential issues with empty b-tree nodes" from Ryusuke Konishi fixes some issues which can occur on corrupted nilfs2 filesystems. - "scripts/decode_stacktrace.sh: improve error reporting and usability" from Luca Ceresoli does those things" * tag 'mm-nonmm-stable-2024-09-21-07-52' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (103 commits) list: test: increase coverage of list_test_list_replace*() list: test: fix tests for list_cut_position() proc: use __auto_type more treewide: correct the typo 'retun' ocfs2: cleanup return value and mlog in ocfs2_global_read_info() nilfs2: remove duplicate 'unlikely()' usage nilfs2: fix potential oob read in nilfs_btree_check_delete() nilfs2: determine empty node blocks as corrupted nilfs2: fix potential null-ptr-deref in nilfs_btree_insert() user_namespace: use kmemdup_array() instead of kmemdup() for multiple allocation tools/mm: rm thp_swap_allocator_test when make clean squashfs: fix percpu address space issues in decompressor_multi_percpu.c lib: glob.c: added null check for character class nilfs2: refactor nilfs_segctor_thread() nilfs2: use kthread_create and kthread_stop for the log writer thread nilfs2: remove sc_timer_task nilfs2: do not repair reserved inode bitmap in nilfs_new_inode() nilfs2: eliminate the shared counter and spinlock for i_generation nilfs2: separate inode type information from i_state field nilfs2: use the BITS_PER_LONG macro ...

mm: add sysfs entry to disable splitting underused THPs

2024-09-09T23:39:04+00:00

If disabled, THPs faulted in or collapsed will not be added to _deferred_list, and therefore won't be considered for splitting under memory pressure if underused. Link: https://lkml.kernel.org/r/20240830100438.3623486-7-usamaarif642@gmail.com Signed-off-by: Usama Arif Cc: Alexander Zhu Cc: Barry Song Cc: David Hildenbrand Cc: Domenico Cerasuolo Cc: Johannes Weiner Cc: Jonathan Corbet Cc: Kairui Song Cc: Matthew Wilcox Cc: Mike Rapoport Cc: Nico Pache Cc: Rik van Riel Cc: Roman Gushchin Cc: Ryan Roberts Cc: Shakeel Butt Cc: Shuang Zhai Cc: Shuang Zhai Cc: Yu Zhao Cc: Hugh Dickins Signed-off-by: Andrew Morton

mm: split underused THPs

2024-09-09T23:39:04+00:00

This is an attempt to mitigate the issue of running out of memory when THP is always enabled. During runtime whenever a THP is being faulted in (__do_huge_pmd_anonymous_page) or collapsed by khugepaged (collapse_huge_page), the THP is added to _deferred_list. Whenever memory reclaim happens in linux, the kernel runs the deferred_split shrinker which goes through the _deferred_list. If the folio was partially mapped, the shrinker attempts to split it. If the folio is not partially mapped, the shrinker checks if the THP was underused, i.e. how many of the base 4K pages of the entire THP were zero-filled. If this number goes above a certain threshold (decided by /sys/kernel/mm/transparent_hugepage/khugepaged/max_ptes_none), the shrinker will attempt to split that THP. Then at remap time, the pages that were zero-filled are mapped to the shared zeropage, hence saving memory. Link: https://lkml.kernel.org/r/20240830100438.3623486-6-usamaarif642@gmail.com Signed-off-by: Usama Arif Suggested-by: Rik van Riel Co-authored-by: Johannes Weiner Cc: Alexander Zhu Cc: Barry Song Cc: David Hildenbrand Cc: Domenico Cerasuolo Cc: Jonathan Corbet Cc: Kairui Song Cc: Matthew Wilcox Cc: Mike Rapoport Cc: Nico Pache Cc: Roman Gushchin Cc: Ryan Roberts Cc: Shakeel Butt Cc: Shuang Zhai Cc: Yu Zhao Cc: Shuang Zhai Cc: Hugh Dickins Signed-off-by: Andrew Morton

Docs/damon: use damonitor GitHub organization instead of awslabs

2024-09-09T23:39:00+00:00

Patch series "Docs/damon: update GitHub repo URLs and maintainer-profile". Replace GitHub URLS on DAMON documents for none-kernel parts DAMON repos with new ones[1] via the first patch. With following two patches, wordsmith maitnainer-profile for better readability, and document the Google clendsar for bi-weekly meetups, respectively. [1] https://lore.kernel.org/20240813232158.83903-1-sj@kernel.org This patch (of 3): GitHub repos for non-kernel parts of DAMON project including 'damo', 'damon-tests' and 'damoos' will be moved[1] from 'awslabs' org to 'damonitor', by 2024-09-05. Update related URLs in kernel tree. [1] https://lore.kernel.org/20240813232158.83903-1-sj@kernel.org Link: https://lkml.kernel.org/r/20240826015741.80707-1-sj@kernel.org Link: https://lkml.kernel.org/r/20240826015741.80707-2-sj@kernel.org Signed-off-by: SeongJae Park Cc: Alex Shi Cc: Hu Haowen <2023002089@link.tyut.edu.cn> Cc: Jonathan Corbet Cc: Yanteng Si Signed-off-by: Andrew Morton

mm: count the number of partially mapped anonymous THPs per size

2024-09-09T23:38:57+00:00

When a THP is added to the deferred_list due to partially mapped, its partial pages are unused, leading to wasted memory and potentially increasing memory reclamation pressure. Detailing the specifics of how unmapping occurs is quite difficult and not that useful, so we adopt a simple approach: each time a THP enters the deferred_list, we increment the count by 1; whenever it leaves for any reason, we decrement the count by 1. Link: https://lkml.kernel.org/r/20240824010441.21308-3-21cnbao@gmail.com Signed-off-by: Barry Song Acked-by: David Hildenbrand Cc: Baolin Wang Cc: Chris Li Cc: Chuanhua Han Cc: Kairui Song Cc: Kalesh Singh Cc: Lance Yang Cc: Ryan Roberts Cc: Shuai Yuan Cc: Usama Arif Cc: Zi Yan Signed-off-by: Andrew Morton

mm: count the number of anonymous THPs per size

2024-09-09T23:38:57+00:00

Patch series "mm: count the number of anonymous THPs per size", v4. Knowing the number of transparent anon THPs in the system is crucial for performance analysis. It helps in understanding the ratio and distribution of THPs versus small folios throughout the system. Additionally, partial unmapping by userspace can lead to significant waste of THPs over time and increase memory reclamation pressure. We need this information for comprehensive system tuning. This patch (of 2): Let's track for each anonymous THP size, how many of them are currently allocated. We'll track the complete lifespan of an anon THP, starting when it becomes an anon THP ("large anon folio") (->mapping gets set), until it gets freed (->mapping gets cleared). Introduce a new "nr_anon" counter per THP size and adjust the corresponding counter in the following cases: * We allocate a new THP and call folio_add_new_anon_rmap() to map it the first time and turn it into an anon THP. * We split an anon THP into multiple smaller ones. * We migrate an anon THP, when we prepare the destination. * We free an anon THP back to the buddy. Note that AnonPages in /proc/meminfo currently tracks the total number of *mapped* anonymous *pages*, and therefore has slightly different semantics. In the future, we might also want to track "nr_anon_mapped" for each THP size, which might be helpful when comparing it to the number of allocated anon THPs (long-term pinning, stuck in swapcache, memory leaks, ...). Further note that for now, we only track anon THPs after they got their ->mapping set, for example via folio_add_new_anon_rmap(). If we would allocate some in the swapcache, they will only show up in the statistics for now after they have been mapped to user space the first time, where we call folio_add_new_anon_rmap(). [akpm@linux-foundation.org: documentation fixups, per David] Link: https://lkml.kernel.org/r/3e8add35-e26b-443b-8a04-1078f4bc78f6@redhat.com Link: https://lkml.kernel.org/r/20240824010441.21308-1-21cnbao@gmail.com Link: https://lkml.kernel.org/r/20240824010441.21308-2-21cnbao@gmail.com Signed-off-by: Barry Song Acked-by: David Hildenbrand Cc: Baolin Wang Cc: Chris Li Cc: Chuanhua Han Cc: Kairui Song Cc: Kalesh Singh Cc: Lance Yang Cc: Ryan Roberts Cc: Shuai Yuan Cc: Usama Arif Cc: Zi Yan Signed-off-by: Andrew Morton

Document/kexec: generalize crash hotplug description

2024-09-02T03:43:37+00:00

Commit 79365026f869 ("crash: add a new kexec flag for hotplug support") generalizes the crash hotplug support to allow architectures to update multiple kexec segments on CPU/Memory hotplug and not just elfcorehdr. Therefore, update the relevant kernel documentation to reflect the same. No functional change. Link: https://lkml.kernel.org/r/20240812041651.703156-1-sourabhjain@linux.ibm.com Signed-off-by: Sourabh Jain Reviewed-by: Petr Tesarik Acked-by: Baoquan He Cc: Hari Bathini Cc: Petr Tesarik Cc: Sourabh Jain Cc: Jonathan Corbet Signed-off-by: Andrew Morton

mm: override mTHP "enabled" defaults at kernel cmdline

2024-09-02T03:26:18+00:00

Add thp_anon= cmdline parameter to allow specifying the default enablement of each supported anon THP size. The parameter accepts the following format and can be provided multiple times to configure each size: thp_anon=,[KMG]:;-[KMG]: An example: thp_anon=16K-64K:always;128K,512K:inherit;256K:madvise;1M-2M:never See Documentation/admin-guide/mm/transhuge.rst for more details. Configuring the defaults at boot time is useful to allow early user space to take advantage of mTHP before its been configured through sysfs. [v-songbaohua@oppo.com: use get_oder() and check size is is_power_of_2] Link: https://lkml.kernel.org/r/20240814224635.43272-1-21cnbao@gmail.com [ryan.roberts@arm.com: some minor cleanup according to David's comments] Link: https://lkml.kernel.org/r/20240820105244.62703-1-21cnbao@gmail.com Link: https://lkml.kernel.org/r/20240814020247.67297-1-21cnbao@gmail.com Signed-off-by: Ryan Roberts Co-developed-by: Barry Song Signed-off-by: Barry Song Reviewed-by: Baolin Wang Tested-by: Baolin Wang Acked-by: David Hildenbrand Cc: Jonathan Corbet Cc: Lance Yang Signed-off-by: Andrew Morton

Merge tag 'mm-stable-2024-07-21-14-50' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2024-07-22T00:15:46+00:00

Pull MM updates from Andrew Morton: - In the series "mm: Avoid possible overflows in dirty throttling" Jan Kara addresses a couple of issues in the writeback throttling code. These fixes are also targetted at -stable kernels. - Ryusuke Konishi's series "nilfs2: fix potential issues related to reserved inodes" does that. This should actually be in the mm-nonmm-stable tree, along with the many other nilfs2 patches. My bad. - More folio conversions from Kefeng Wang in the series "mm: convert to folio_alloc_mpol()" - Kemeng Shi has sent some cleanups to the writeback code in the series "Add helper functions to remove repeated code and improve readability of cgroup writeback" - Kairui Song has made the swap code a little smaller and a little faster in the series "mm/swap: clean up and optimize swap cache index". - In the series "mm/memory: cleanly support zeropage in vm_insert_page*(), vm_map_pages*() and vmf_insert_mixed()" David Hildenbrand has reworked the rather sketchy handling of the use of the zeropage in MAP_SHARED mappings. I don't see any runtime effects here - more a cleanup/understandability/maintainablity thing. - Dev Jain has improved selftests/mm/va_high_addr_switch.c's handling of higher addresses, for aarch64. The (poorly named) series is "Restructure va_high_addr_switch". - The core TLB handling code gets some cleanups and possible slight optimizations in Bang Li's series "Add update_mmu_tlb_range() to simplify code". - Jane Chu has improved the handling of our fake-an-unrecoverable-memory-error testing feature MADV_HWPOISON in the series "Enhance soft hwpoison handling and injection". - Jeff Johnson has sent a billion patches everywhere to add MODULE_DESCRIPTION() to everything. Some landed in this pull. - In the series "mm: cleanup MIGRATE_SYNC_NO_COPY mode", Kefeng Wang has simplified migration's use of hardware-offload memory copying. - Yosry Ahmed performs more folio API conversions in his series "mm: zswap: trivial folio conversions". - In the series "large folios swap-in: handle refault cases first", Chuanhua Han inches us forward in the handling of large pages in the swap code. This is a cleanup and optimization, working toward the end objective of full support of large folio swapin/out. - In the series "mm,swap: cleanup VMA based swap readahead window calculation", Huang Ying has contributed some cleanups and a possible fixlet to his VMA based swap readahead code. - In the series "add mTHP support for anonymous shmem" Baolin Wang has taught anonymous shmem mappings to use multisize THP. By default this is a no-op - users must opt in vis sysfs controls. Dramatic improvements in pagefault latency are realized. - David Hildenbrand has some cleanups to our remaining use of page_mapcount() in the series "fs/proc: move page_mapcount() to fs/proc/internal.h". - David also has some highmem accounting cleanups in the series "mm/highmem: don't track highmem pages manually". - Build-time fixes and cleanups from John Hubbard in the series "cleanups, fixes, and progress towards avoiding "make headers"". - Cleanups and consolidation of the core pagemap handling from Barry Song in the series "mm: introduce pmd|pte_needs_soft_dirty_wp helpers and utilize them". - Lance Yang's series "Reclaim lazyfree THP without splitting" has reduced the latency of the reclaim of pmd-mapped THPs under fairly common circumstances. A 10x speedup is seen in a microbenchmark. It does this by punting to aother CPU but I guess that's a win unless all CPUs are pegged. - hugetlb_cgroup cleanups from Xiu Jianfeng in the series "mm/hugetlb_cgroup: rework on cftypes". - Miaohe Lin's series "Some cleanups for memory-failure" does just that thing. - Someone other than SeongJae has developed a DAMON feature in Honggyu Kim's series "DAMON based tiered memory management for CXL memory". This adds DAMON features which may be used to help determine the efficiency of our placement of CXL/PCIe attached DRAM. - DAMON user API centralization and simplificatio work in SeongJae Park's series "mm/damon: introduce DAMON parameters online commit function". - In the series "mm: page_type, zsmalloc and page_mapcount_reset()" David Hildenbrand does some maintenance work on zsmalloc - partially modernizing its use of pageframe fields. - Kefeng Wang provides more folio conversions in the series "mm: remove page_maybe_dma_pinned() and page_mkclean()". - More cleanup from David Hildenbrand, this time in the series "mm/memory_hotplug: use PageOffline() instead of PageReserved() for !ZONE_DEVICE". It "enlightens memory hotplug more about PageOffline() pages" and permits the removal of some virtio-mem hacks. - Barry Song's series "mm: clarify folio_add_new_anon_rmap() and __folio_add_anon_rmap()" is a cleanup to the anon folio handling in preparation for mTHP (multisize THP) swapin. - Kefeng Wang's series "mm: improve clear and copy user folio" implements more folio conversions, this time in the area of large folio userspace copying. - The series "Docs/mm/damon/maintaier-profile: document a mailing tool and community meetup series" tells people how to get better involved with other DAMON developers. From SeongJae Park. - A large series ("kmsan: Enable on s390") from Ilya Leoshkevich does that. - David Hildenbrand sends along more cleanups, this time against the migration code. The series is "mm/migrate: move NUMA hinting fault folio isolation + checks under PTL". - Jan Kara has found quite a lot of strangenesses and minor errors in the readahead code. He addresses this in the series "mm: Fix various readahead quirks". - SeongJae Park's series "selftests/damon: test DAMOS tried regions and {min,max}_nr_regions" adds features and addresses errors in DAMON's self testing code. - Gavin Shan has found a userspace-triggerable WARN in the pagecache code. The series "mm/filemap: Limit page cache size to that supported by xarray" addresses this. The series is marked cc:stable. - Chengming Zhou's series "mm/ksm: cmp_and_merge_page() optimizations and cleanup" cleans up and slightly optimizes KSM. - Roman Gushchin has separated the memcg-v1 and memcg-v2 code - lots of code motion. The series (which also makes the memcg-v1 code Kconfigurable) are "mm: memcg: separate legacy cgroup v1 code and put under config option" and "mm: memcg: put cgroup v1-specific memcg data under CONFIG_MEMCG_V1" - Dan Schatzberg's series "Add swappiness argument to memory.reclaim" adds an additional feature to this cgroup-v2 control file. - The series "Userspace controls soft-offline pages" from Jiaqi Yan permits userspace to stop the kernel's automatic treatment of excessive correctable memory errors. In order to permit userspace to monitor and handle this situation. - Kefeng Wang's series "mm: migrate: support poison recover from migrate folio" teaches the kernel to appropriately handle migration from poisoned source folios rather than simply panicing. - SeongJae Park's series "Docs/damon: minor fixups and improvements" does those things. - In the series "mm/zsmalloc: change back to per-size_class lock" Chengming Zhou improves zsmalloc's scalability and memory utilization. - Vivek Kasireddy's series "mm/gup: Introduce memfd_pin_folios() for pinning memfd folios" makes the GUP code use FOLL_PIN rather than bare refcount increments. So these paes can first be moved aside if they reside in the movable zone or a CMA block. - Andrii Nakryiko has added a binary ioctl()-based API to /proc/pid/maps for much faster reading of vma information. The series is "query VMAs from /proc//maps". - In the series "mm: introduce per-order mTHP split counters" Lance Yang improves the kernel's presentation of developer information related to multisize THP splitting. - Michael Ellerman has developed the series "Reimplement huge pages without hugepd on powerpc (8xx, e500, book3s/64)". This permits userspace to use all available huge page sizes. - In the series "revert unconditional slab and page allocator fault injection calls" Vlastimil Babka removes a performance-affecting and not very useful feature from slab fault injection. * tag 'mm-stable-2024-07-21-14-50' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (411 commits) mm/mglru: fix ineffective protection calculation mm/zswap: fix a white space issue mm/hugetlb: fix kernel NULL pointer dereference when migrating hugetlb folio mm/hugetlb: fix possible recursive locking detected warning mm/gup: clear the LRU flag of a page before adding to LRU batch mm/numa_balancing: teach mpol_to_str about the balancing mode mm: memcg1: convert charge move flags to unsigned long long alloc_tag: fix page_ext_get/page_ext_put sequence during page splitting lib: reuse page_ext_data() to obtain codetag_ref lib: add missing newline character in the warning message mm/mglru: fix overshooting shrinker memory mm/mglru: fix div-by-zero in vmpressure_calc_level() mm/kmemleak: replace strncpy() with strscpy() mm, page_alloc: put should_fail_alloc_page() back behing CONFIG_FAIL_PAGE_ALLOC mm, slab: put should_failslab() back behind CONFIG_SHOULD_FAILSLAB mm: ignore data-race in __swap_writepage hugetlbfs: ensure generic_hugetlb_get_unmapped_area() returns higher address than mmap_min_addr mm: shmem: rename mTHP shmem counters mm: swap_state: use folio_alloc_mpol() in __read_swap_cache_async() mm/migrate: putback split folios when numa hint migration fails ...