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[merged mm-hotfixes-stable] mm-memory-do-not-populate-page-table-entries-beyond-i_size.patch removed from -mm tree

by Andrew Morton

The quilt patch titled Subject: mm/memory: do not populate page table entries beyond i_size has been removed from the -mm tree. Its filename was mm-memory-do-not-populate-page-table-entries-beyond-i_size.patch This patch was dropped because it was merged into the mm-hotfixes-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: Kiryl Shutsemau <kas(a)kernel.org> Subject: mm/memory: do not populate page table entries beyond i_size Date: Mon, 27 Oct 2025 11:56:35 +0000 Patch series "Fix SIGBUS semantics with large folios", v3. Accessing memory within a VMA, but beyond i_size rounded up to the next page size, is supposed to generate SIGBUS. Darrick reported[1] an xfstests regression in v6.18-rc1. generic/749 failed due to missing SIGBUS. This was caused by my recent changes that try to fault in the whole folio where possible: 19773df031bc ("mm/fault: try to map the entire file folio in finish_fault()") 357b92761d94 ("mm/filemap: map entire large folio faultaround") These changes did not consider i_size when setting up PTEs, leading to xfstest breakage. However, the problem has been present in the kernel for a long time - since huge tmpfs was introduced in 2016. The kernel happily maps PMD-sized folios as PMD without checking i_size. And huge=always tmpfs allocates PMD-size folios on any writes. I considered this corner case when I implemented a large tmpfs, and my conclusion was that no one in their right mind should rely on receiving a SIGBUS signal when accessing beyond i_size. I cannot imagine how it could be useful for the workload. But apparently filesystem folks care a lot about preserving strict SIGBUS semantics. Generic/749 was introduced last year with reference to POSIX, but no real workloads were mentioned. It also acknowledged the tmpfs deviation from the test case. POSIX indeed says[3]: References within the address range starting at pa and continuing for len bytes to whole pages following the end of an object shall result in delivery of a SIGBUS signal. The patchset fixes the regression introduced by recent changes as well as more subtle SIGBUS breakage due to split failure on truncation. This patch (of 2): Accesses within VMA, but beyond i_size rounded up to PAGE_SIZE are supposed to generate SIGBUS. Recent changes attempted to fault in full folio where possible. They did not respect i_size, which led to populating PTEs beyond i_size and breaking SIGBUS semantics. Darrick reported generic/749 breakage because of this. However, the problem existed before the recent changes. With huge=always tmpfs, any write to a file leads to PMD-size allocation. Following the fault-in of the folio will install PMD mapping regardless of i_size. Fix filemap_map_pages() and finish_fault() to not install: - PTEs beyond i_size; - PMD mappings across i_size; Make an exception for shmem/tmpfs that for long time intentionally mapped with PMDs across i_size. Link: https://lkml.kernel.org/r/20251027115636.82382-1-kirill@shutemov.name Link: https://lkml.kernel.org/r/20251027115636.82382-2-kirill@shutemov.name Signed-off-by: Kiryl Shutsemau <kas(a)kernel.org> Fixes: 6795801366da ("xfs: Support large folios") Reported-by: "Darrick J. Wong" <djwong(a)kernel.org> Cc: Al Viro <viro(a)zeniv.linux.org.uk> Cc: Baolin Wang <baolin.wang(a)linux.alibaba.com> Cc: Christian Brauner <brauner(a)kernel.org> Cc: Dave Chinner <david(a)fromorbit.com> Cc: David Hildenbrand <david(a)redhat.com> Cc: Hugh Dickins <hughd(a)google.com> Cc: Johannes Weiner <hannes(a)cmpxchg.org> Cc: Liam Howlett <liam.howlett(a)oracle.com> Cc: Lorenzo Stoakes <lorenzo.stoakes(a)oracle.com> Cc: Matthew Wilcox (Oracle) <willy(a)infradead.org> Cc: Michal Hocko <mhocko(a)suse.com> Cc: Mike Rapoport <rppt(a)kernel.org> Cc: Rik van Riel <riel(a)surriel.com> Cc: Shakeel Butt <shakeel.butt(a)linux.dev> Cc: Suren Baghdasaryan <surenb(a)google.com> Cc: Vlastimil Babka <vbabka(a)suse.cz> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/filemap.c | 28 ++++++++++++++++++++-------- mm/memory.c | 20 +++++++++++++++++++- 2 files changed, 39 insertions(+), 9 deletions(-) --- a/mm/filemap.c~mm-memory-do-not-populate-page-table-entries-beyond-i_size +++ a/mm/filemap.c @@ -3681,7 +3681,8 @@ skip: static vm_fault_t filemap_map_folio_range(struct vm_fault *vmf, struct folio *folio, unsigned long start, unsigned long addr, unsigned int nr_pages, - unsigned long *rss, unsigned short *mmap_miss) + unsigned long *rss, unsigned short *mmap_miss, + bool can_map_large) { unsigned int ref_from_caller = 1; vm_fault_t ret = 0; @@ -3696,7 +3697,7 @@ static vm_fault_t filemap_map_folio_rang * The folio must not cross VMA or page table boundary. */ addr0 = addr - start * PAGE_SIZE; - if (folio_within_vma(folio, vmf->vma) && + if (can_map_large && folio_within_vma(folio, vmf->vma) && (addr0 & PMD_MASK) == ((addr0 + folio_size(folio) - 1) & PMD_MASK)) { vmf->pte -= start; page -= start; @@ -3811,13 +3812,27 @@ vm_fault_t filemap_map_pages(struct vm_f unsigned long rss = 0; unsigned int nr_pages = 0, folio_type; unsigned short mmap_miss = 0, mmap_miss_saved; + bool can_map_large; rcu_read_lock(); folio = next_uptodate_folio(&xas, mapping, end_pgoff); if (!folio) goto out; - if (filemap_map_pmd(vmf, folio, start_pgoff)) { + file_end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE) - 1; + end_pgoff = min(end_pgoff, file_end); + + /* + * Do not allow to map with PTEs beyond i_size and with PMD + * across i_size to preserve SIGBUS semantics. + * + * Make an exception for shmem/tmpfs that for long time + * intentionally mapped with PMDs across i_size. + */ + can_map_large = shmem_mapping(mapping) || + file_end >= folio_next_index(folio); + + if (can_map_large && filemap_map_pmd(vmf, folio, start_pgoff)) { ret = VM_FAULT_NOPAGE; goto out; } @@ -3830,10 +3845,6 @@ vm_fault_t filemap_map_pages(struct vm_f goto out; } - file_end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE) - 1; - if (end_pgoff > file_end) - end_pgoff = file_end; - folio_type = mm_counter_file(folio); do { unsigned long end; @@ -3850,7 +3861,8 @@ vm_fault_t filemap_map_pages(struct vm_f else ret |= filemap_map_folio_range(vmf, folio, xas.xa_index - folio->index, addr, - nr_pages, &rss, &mmap_miss); + nr_pages, &rss, &mmap_miss, + can_map_large); folio_unlock(folio); } while ((folio = next_uptodate_folio(&xas, mapping, end_pgoff)) != NULL); --- a/mm/memory.c~mm-memory-do-not-populate-page-table-entries-beyond-i_size +++ a/mm/memory.c @@ -65,6 +65,7 @@ #include <linux/gfp.h> #include <linux/migrate.h> #include <linux/string.h> +#include <linux/shmem_fs.h> #include <linux/memory-tiers.h> #include <linux/debugfs.h> #include <linux/userfaultfd_k.h> @@ -5501,8 +5502,25 @@ fallback: return ret; } + if (!needs_fallback && vma->vm_file) { + struct address_space *mapping = vma->vm_file->f_mapping; + pgoff_t file_end; + + file_end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE); + + /* + * Do not allow to map with PTEs beyond i_size and with PMD + * across i_size to preserve SIGBUS semantics. + * + * Make an exception for shmem/tmpfs that for long time + * intentionally mapped with PMDs across i_size. + */ + needs_fallback = !shmem_mapping(mapping) && + file_end < folio_next_index(folio); + } + if (pmd_none(*vmf->pmd)) { - if (folio_test_pmd_mappable(folio)) { + if (!needs_fallback && folio_test_pmd_mappable(folio)) { ret = do_set_pmd(vmf, folio, page); if (ret != VM_FAULT_FALLBACK) return ret; _ Patches currently in -mm which might be from kas(a)kernel.org are

2 days, 23 hours

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[merged mm-hotfixes-stable] fs-proc-fix-uaf-in-proc_readdir_de.patch removed from -mm tree

by Andrew Morton

The quilt patch titled Subject: fs/proc: fix uaf in proc_readdir_de() has been removed from the -mm tree. Its filename was fs-proc-fix-uaf-in-proc_readdir_de.patch This patch was dropped because it was merged into the mm-hotfixes-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: Wei Yang <albinwyang(a)tencent.com> Subject: fs/proc: fix uaf in proc_readdir_de() Date: Sat, 25 Oct 2025 10:42:33 +0800 Pde is erased from subdir rbtree through rb_erase(), but not set the node to EMPTY, which may result in uaf access. We should use RB_CLEAR_NODE() set the erased node to EMPTY, then pde_subdir_next() will return NULL to avoid uaf access. We found an uaf issue while using stress-ng testing, need to run testcase getdent and tun in the same time. The steps of the issue is as follows: 1) use getdent to traverse dir /proc/pid/net/dev_snmp6/, and current pde is tun3; 2) in the [time windows] unregister netdevice tun3 and tun2, and erase them from rbtree. erase tun3 first, and then erase tun2. the pde(tun2) will be released to slab; 3) continue to getdent process, then pde_subdir_next() will return pde(tun2) which is released, it will case uaf access. CPU 0 | CPU 1 ------------------------------------------------------------------------- traverse dir /proc/pid/net/dev_snmp6/ | unregister_netdevice(tun->dev) //tun3 tun2 sys_getdents64() | iterate_dir() | proc_readdir() | proc_readdir_de() | snmp6_unregister_dev() pde_get(de); | proc_remove() read_unlock(&proc_subdir_lock); | remove_proc_subtree() | write_lock(&proc_subdir_lock); [time window] | rb_erase(&root->subdir_node, &parent->subdir); | write_unlock(&proc_subdir_lock); read_lock(&proc_subdir_lock); | next = pde_subdir_next(de); | pde_put(de); | de = next; //UAF | rbtree of dev_snmp6 | pde(tun3) / \ NULL pde(tun2) Link: https://lkml.kernel.org/r/20251025024233.158363-1-albin_yang@163.com Signed-off-by: Wei Yang <albinwyang(a)tencent.com> Cc: Al Viro <viro(a)zeniv.linux.org.uk> Cc: Christian Brauner <brauner(a)kernel.org> Cc: wangzijie <wangzijie1(a)honor.com> Cc: Alexey Dobriyan <adobriyan(a)gmail.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- fs/proc/generic.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) --- a/fs/proc/generic.c~fs-proc-fix-uaf-in-proc_readdir_de +++ a/fs/proc/generic.c @@ -698,6 +698,12 @@ void pde_put(struct proc_dir_entry *pde) } } +static void pde_erase(struct proc_dir_entry *pde, struct proc_dir_entry *parent) +{ + rb_erase(&pde->subdir_node, &parent->subdir); + RB_CLEAR_NODE(&pde->subdir_node); +} + /* * Remove a /proc entry and free it if it's not currently in use. */ @@ -720,7 +726,7 @@ void remove_proc_entry(const char *name, WARN(1, "removing permanent /proc entry '%s'", de->name); de = NULL; } else { - rb_erase(&de->subdir_node, &parent->subdir); + pde_erase(de, parent); if (S_ISDIR(de->mode)) parent->nlink--; } @@ -764,7 +770,7 @@ int remove_proc_subtree(const char *name root->parent->name, root->name); return -EINVAL; } - rb_erase(&root->subdir_node, &parent->subdir); + pde_erase(root, parent); de = root; while (1) { @@ -776,7 +782,7 @@ int remove_proc_subtree(const char *name next->parent->name, next->name); return -EINVAL; } - rb_erase(&next->subdir_node, &de->subdir); + pde_erase(next, de); de = next; continue; } _ Patches currently in -mm which might be from albinwyang(a)tencent.com are

2 days, 23 hours

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[merged mm-hotfixes-stable] mm-huge_memory-preserve-pg_has_hwpoisoned-if-a-folio-is-split-to-0-order.patch removed from -mm tree

by Andrew Morton

The quilt patch titled Subject: mm/huge_memory: preserve PG_has_hwpoisoned if a folio is split to >0 order has been removed from the -mm tree. Its filename was mm-huge_memory-preserve-pg_has_hwpoisoned-if-a-folio-is-split-to-0-order.patch This patch was dropped because it was merged into the mm-hotfixes-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: Zi Yan <ziy(a)nvidia.com> Subject: mm/huge_memory: preserve PG_has_hwpoisoned if a folio is split to >0 order Date: Wed, 22 Oct 2025 23:05:21 -0400 folio split clears PG_has_hwpoisoned, but the flag should be preserved in after-split folios containing pages with PG_hwpoisoned flag if the folio is split to >0 order folios. Scan all pages in a to-be-split folio to determine which after-split folios need the flag. An alternatives is to change PG_has_hwpoisoned to PG_maybe_hwpoisoned to avoid the scan and set it on all after-split folios, but resulting false positive has undesirable negative impact. To remove false positive, caller of folio_test_has_hwpoisoned() and folio_contain_hwpoisoned_page() needs to do the scan. That might be causing a hassle for current and future callers and more costly than doing the scan in the split code. More details are discussed in [1]. This issue can be exposed via: 1. splitting a has_hwpoisoned folio to >0 order from debugfs interface; 2. truncating part of a has_hwpoisoned folio in truncate_inode_partial_folio(). And later accesses to a hwpoisoned page could be possible due to the missing has_hwpoisoned folio flag. This will lead to MCE errors. Link: https://lore.kernel.org/all/CAHbLzkoOZm0PXxE9qwtF4gKR=cpRXrSrJ9V9Pm2DJexs98… [1] Link: https://lkml.kernel.org/r/20251023030521.473097-1-ziy@nvidia.com Fixes: c010d47f107f ("mm: thp: split huge page to any lower order pages") Signed-off-by: Zi Yan <ziy(a)nvidia.com> Acked-by: David Hildenbrand <david(a)redhat.com> Reviewed-by: Yang Shi <yang(a)os.amperecomputing.com> Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes(a)oracle.com> Reviewed-by: Lance Yang <lance.yang(a)linux.dev> Reviewed-by: Miaohe Lin <linmiaohe(a)huawei.com> Reviewed-by: Baolin Wang <baolin.wang(a)linux.alibaba.com> Reviewed-by: Wei Yang <richard.weiyang(a)gmail.com> Cc: Pankaj Raghav <kernel(a)pankajraghav.com> Cc: Barry Song <baohua(a)kernel.org> Cc: Dev Jain <dev.jain(a)arm.com> Cc: Jane Chu <jane.chu(a)oracle.com> Cc: Liam Howlett <liam.howlett(a)oracle.com> Cc: Luis Chamberalin <mcgrof(a)kernel.org> Cc: Matthew Wilcox (Oracle) <willy(a)infradead.org> Cc: Naoya Horiguchi <nao.horiguchi(a)gmail.com> Cc: Nico Pache <npache(a)redhat.com> Cc: Ryan Roberts <ryan.roberts(a)arm.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/huge_memory.c | 23 ++++++++++++++++++++--- 1 file changed, 20 insertions(+), 3 deletions(-) --- a/mm/huge_memory.c~mm-huge_memory-preserve-pg_has_hwpoisoned-if-a-folio-is-split-to-0-order +++ a/mm/huge_memory.c @@ -3263,6 +3263,14 @@ bool can_split_folio(struct folio *folio caller_pins; } +static bool page_range_has_hwpoisoned(struct page *page, long nr_pages) +{ + for (; nr_pages; page++, nr_pages--) + if (PageHWPoison(page)) + return true; + return false; +} + /* * It splits @folio into @new_order folios and copies the @folio metadata to * all the resulting folios. @@ -3270,17 +3278,24 @@ bool can_split_folio(struct folio *folio static void __split_folio_to_order(struct folio *folio, int old_order, int new_order) { + /* Scan poisoned pages when split a poisoned folio to large folios */ + const bool handle_hwpoison = folio_test_has_hwpoisoned(folio) && new_order; long new_nr_pages = 1 << new_order; long nr_pages = 1 << old_order; long i; + folio_clear_has_hwpoisoned(folio); + + /* Check first new_nr_pages since the loop below skips them */ + if (handle_hwpoison && + page_range_has_hwpoisoned(folio_page(folio, 0), new_nr_pages)) + folio_set_has_hwpoisoned(folio); /* * Skip the first new_nr_pages, since the new folio from them have all * the flags from the original folio. */ for (i = new_nr_pages; i < nr_pages; i += new_nr_pages) { struct page *new_head = &folio->page + i; - /* * Careful: new_folio is not a "real" folio before we cleared PageTail. * Don't pass it around before clear_compound_head(). @@ -3322,6 +3337,10 @@ static void __split_folio_to_order(struc (1L << PG_dirty) | LRU_GEN_MASK | LRU_REFS_MASK)); + if (handle_hwpoison && + page_range_has_hwpoisoned(new_head, new_nr_pages)) + folio_set_has_hwpoisoned(new_folio); + new_folio->mapping = folio->mapping; new_folio->index = folio->index + i; @@ -3422,8 +3441,6 @@ static int __split_unmapped_folio(struct if (folio_test_anon(folio)) mod_mthp_stat(order, MTHP_STAT_NR_ANON, -1); - folio_clear_has_hwpoisoned(folio); - /* * split to new_order one order at a time. For uniform split, * folio is split to new_order directly. _ Patches currently in -mm which might be from ziy(a)nvidia.com are mm-huge_memory-fix-folio-split-check-for-anon-folios-in-swapcache.patch mm-huge_memory-add-split_huge_page_to_order.patch mm-memory-failure-improve-large-block-size-folio-handling.patch mm-huge_memory-fix-kernel-doc-comments-for-folio_split-and-related.patch mm-huge_memory-fix-kernel-doc-comments-for-folio_split-and-related-fix.patch mm-huge_memory-fix-kernel-doc-comments-for-folio_split-and-related-fix-2.patch migrate-optimise-alloc_migration_target-fix.patch

2 days, 23 hours

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[merged mm-hotfixes-stable] ksm-use-range-walk-function-to-jump-over-holes-in-scan_get_next_rmap_item.patch removed from -mm tree

by Andrew Morton

The quilt patch titled Subject: ksm: use range-walk function to jump over holes in scan_get_next_rmap_item has been removed from the -mm tree. Its filename was ksm-use-range-walk-function-to-jump-over-holes-in-scan_get_next_rmap_item.patch This patch was dropped because it was merged into the mm-hotfixes-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: Pedro Demarchi Gomes <pedrodemargomes(a)gmail.com> Subject: ksm: use range-walk function to jump over holes in scan_get_next_rmap_item Date: Wed, 22 Oct 2025 12:30:59 -0300 Currently, scan_get_next_rmap_item() walks every page address in a VMA to locate mergeable pages. This becomes highly inefficient when scanning large virtual memory areas that contain mostly unmapped regions, causing ksmd to use large amount of cpu without deduplicating much pages. This patch replaces the per-address lookup with a range walk using walk_page_range(). The range walker allows KSM to skip over entire unmapped holes in a VMA, avoiding unnecessary lookups. This problem was previously discussed in [1]. Consider the following test program which creates a 32 TiB mapping in the virtual address space but only populates a single page: #include <unistd.h> #include <stdio.h> #include <sys/mman.h> /* 32 TiB */ const size_t size = 32ul * 1024 * 1024 * 1024 * 1024; int main() { char *area = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_NORESERVE | MAP_PRIVATE | MAP_ANON, -1, 0); if (area == MAP_FAILED) { perror("mmap() failed\n"); return -1; } /* Populate a single page such that we get an anon_vma. */ *area = 0; /* Enable KSM. */ madvise(area, size, MADV_MERGEABLE); pause(); return 0; } $ ./ksm-sparse & $ echo 1 > /sys/kernel/mm/ksm/run Without this patch ksmd uses 100% of the cpu for a long time (more then 1 hour in my test machine) scanning all the 32 TiB virtual address space that contain only one mapped page. This makes ksmd essentially deadlocked not able to deduplicate anything of value. With this patch ksmd walks only the one mapped page and skips the rest of the 32 TiB virtual address space, making the scan fast using little cpu. Link: https://lkml.kernel.org/r/20251023035841.41406-1-pedrodemargomes@gmail.com Link: https://lkml.kernel.org/r/20251022153059.22763-1-pedrodemargomes@gmail.com Link: https://lore.kernel.org/linux-mm/423de7a3-1c62-4e72-8e79-19a6413e420c@redha… [1] Fixes: 31dbd01f3143 ("ksm: Kernel SamePage Merging") Signed-off-by: Pedro Demarchi Gomes <pedrodemargomes(a)gmail.com> Co-developed-by: David Hildenbrand <david(a)redhat.com> Signed-off-by: David Hildenbrand <david(a)redhat.com> Reported-by: craftfever <craftfever(a)airmail.cc> Closes: https://lkml.kernel.org/r/020cf8de6e773bb78ba7614ef250129f11a63781@murena.io Suggested-by: David Hildenbrand <david(a)redhat.com> Acked-by: David Hildenbrand <david(a)redhat.com> Cc: Chengming Zhou <chengming.zhou(a)linux.dev> Cc: xu xin <xu.xin16(a)zte.com.cn> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/ksm.c | 113 ++++++++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 104 insertions(+), 9 deletions(-) --- a/mm/ksm.c~ksm-use-range-walk-function-to-jump-over-holes-in-scan_get_next_rmap_item +++ a/mm/ksm.c @@ -2455,6 +2455,95 @@ static bool should_skip_rmap_item(struct return true; } +struct ksm_next_page_arg { + struct folio *folio; + struct page *page; + unsigned long addr; +}; + +static int ksm_next_page_pmd_entry(pmd_t *pmdp, unsigned long addr, unsigned long end, + struct mm_walk *walk) +{ + struct ksm_next_page_arg *private = walk->private; + struct vm_area_struct *vma = walk->vma; + pte_t *start_ptep = NULL, *ptep, pte; + struct mm_struct *mm = walk->mm; + struct folio *folio; + struct page *page; + spinlock_t *ptl; + pmd_t pmd; + + if (ksm_test_exit(mm)) + return 0; + + cond_resched(); + + pmd = pmdp_get_lockless(pmdp); + if (!pmd_present(pmd)) + return 0; + + if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && pmd_leaf(pmd)) { + ptl = pmd_lock(mm, pmdp); + pmd = pmdp_get(pmdp); + + if (!pmd_present(pmd)) { + goto not_found_unlock; + } else if (pmd_leaf(pmd)) { + page = vm_normal_page_pmd(vma, addr, pmd); + if (!page) + goto not_found_unlock; + folio = page_folio(page); + + if (folio_is_zone_device(folio) || !folio_test_anon(folio)) + goto not_found_unlock; + + page += ((addr & (PMD_SIZE - 1)) >> PAGE_SHIFT); + goto found_unlock; + } + spin_unlock(ptl); + } + + start_ptep = pte_offset_map_lock(mm, pmdp, addr, &ptl); + if (!start_ptep) + return 0; + + for (ptep = start_ptep; addr < end; ptep++, addr += PAGE_SIZE) { + pte = ptep_get(ptep); + + if (!pte_present(pte)) + continue; + + page = vm_normal_page(vma, addr, pte); + if (!page) + continue; + folio = page_folio(page); + + if (folio_is_zone_device(folio) || !folio_test_anon(folio)) + continue; + goto found_unlock; + } + +not_found_unlock: + spin_unlock(ptl); + if (start_ptep) + pte_unmap(start_ptep); + return 0; +found_unlock: + folio_get(folio); + spin_unlock(ptl); + if (start_ptep) + pte_unmap(start_ptep); + private->page = page; + private->folio = folio; + private->addr = addr; + return 1; +} + +static struct mm_walk_ops ksm_next_page_ops = { + .pmd_entry = ksm_next_page_pmd_entry, + .walk_lock = PGWALK_RDLOCK, +}; + static struct ksm_rmap_item *scan_get_next_rmap_item(struct page **page) { struct mm_struct *mm; @@ -2542,21 +2631,27 @@ next_mm: ksm_scan.address = vma->vm_end; while (ksm_scan.address < vma->vm_end) { + struct ksm_next_page_arg ksm_next_page_arg; struct page *tmp_page = NULL; - struct folio_walk fw; struct folio *folio; if (ksm_test_exit(mm)) break; - folio = folio_walk_start(&fw, vma, ksm_scan.address, 0); - if (folio) { - if (!folio_is_zone_device(folio) && - folio_test_anon(folio)) { - folio_get(folio); - tmp_page = fw.page; - } - folio_walk_end(&fw, vma); + int found; + + found = walk_page_range_vma(vma, ksm_scan.address, + vma->vm_end, + &ksm_next_page_ops, + &ksm_next_page_arg); + + if (found > 0) { + folio = ksm_next_page_arg.folio; + tmp_page = ksm_next_page_arg.page; + ksm_scan.address = ksm_next_page_arg.addr; + } else { + VM_WARN_ON_ONCE(found < 0); + ksm_scan.address = vma->vm_end - PAGE_SIZE; } if (tmp_page) { _ Patches currently in -mm which might be from pedrodemargomes(a)gmail.com are revert-mm-ksm-convert-break_ksm-from-walk_page_range_vma-to-folio_walk.patch ksm-perform-a-range-walk-in-break_ksm.patch ksm-replace-function-unmerge_ksm_pages-with-break_ksm.patch

2 days, 23 hours

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[merged mm-hotfixes-stable] mm-kmsan-fix-kmsan-kmalloc-hook-when-no-stack-depots-are-allocated-yet.patch removed from -mm tree

by Andrew Morton

The quilt patch titled Subject: mm/kmsan: fix kmsan kmalloc hook when no stack depots are allocated yet has been removed from the -mm tree. Its filename was mm-kmsan-fix-kmsan-kmalloc-hook-when-no-stack-depots-are-allocated-yet.patch This patch was dropped because it was merged into the mm-hotfixes-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: Aleksei Nikiforov <aleksei.nikiforov(a)linux.ibm.com> Subject: mm/kmsan: fix kmsan kmalloc hook when no stack depots are allocated yet Date: Tue, 30 Sep 2025 13:56:01 +0200 If no stack depot is allocated yet, due to masking out __GFP_RECLAIM flags kmsan called from kmalloc cannot allocate stack depot. kmsan fails to record origin and report issues. This may result in KMSAN failing to report issues. Reusing flags from kmalloc without modifying them should be safe for kmsan. For example, such chain of calls is possible: test_uninit_kmalloc -> kmalloc -> __kmalloc_cache_noprof -> slab_alloc_node -> slab_post_alloc_hook -> kmsan_slab_alloc -> kmsan_internal_poison_memory. Only when it is called in a context without flags present should __GFP_RECLAIM flags be masked. With this change all kmsan tests start working reliably. Eric reported: : Yes, KMSAN seems to be at least partially broken currently. Besides the : fact that the kmsan KUnit test is currently failing (which I reported at : https://lore.kernel.org/r/20250911175145.GA1376@sol), I've confirmed that : the poly1305 KUnit test causes a KMSAN warning with Aleksei's patch : applied but does not cause a warning without it. The warning did get : reached via syzbot somehow : (https://lore.kernel.org/r/751b3d80293a6f599bb07770afcef24f623c7da0.17610263…), : so KMSAN must still work in some cases. But it didn't work for me. Link: https://lkml.kernel.org/r/20250930115600.709776-2-aleksei.nikiforov@linux.i… Link: https://lkml.kernel.org/r/20251022030213.GA35717@sol Fixes: 97769a53f117 ("mm, bpf: Introduce try_alloc_pages() for opportunistic page allocation") Signed-off-by: Aleksei Nikiforov <aleksei.nikiforov(a)linux.ibm.com> Reviewed-by: Alexander Potapenko <glider(a)google.com> Tested-by: Eric Biggers <ebiggers(a)kernel.org> Cc: Alexei Starovoitov <ast(a)kernel.org> Cc: Dmitriy Vyukov <dvyukov(a)google.com> Cc: Ilya Leoshkevich <iii(a)linux.ibm.com> Cc: Marco Elver <elver(a)google.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/kmsan/core.c | 3 --- mm/kmsan/hooks.c | 6 ++++-- mm/kmsan/shadow.c | 2 +- 3 files changed, 5 insertions(+), 6 deletions(-) --- a/mm/kmsan/core.c~mm-kmsan-fix-kmsan-kmalloc-hook-when-no-stack-depots-are-allocated-yet +++ a/mm/kmsan/core.c @@ -72,9 +72,6 @@ depot_stack_handle_t kmsan_save_stack_wi nr_entries = stack_trace_save(entries, KMSAN_STACK_DEPTH, 0); - /* Don't sleep. */ - flags &= ~(__GFP_DIRECT_RECLAIM | __GFP_KSWAPD_RECLAIM); - handle = stack_depot_save(entries, nr_entries, flags); return stack_depot_set_extra_bits(handle, extra); } --- a/mm/kmsan/hooks.c~mm-kmsan-fix-kmsan-kmalloc-hook-when-no-stack-depots-are-allocated-yet +++ a/mm/kmsan/hooks.c @@ -84,7 +84,8 @@ void kmsan_slab_free(struct kmem_cache * if (s->ctor) return; kmsan_enter_runtime(); - kmsan_internal_poison_memory(object, s->object_size, GFP_KERNEL, + kmsan_internal_poison_memory(object, s->object_size, + GFP_KERNEL & ~(__GFP_RECLAIM), KMSAN_POISON_CHECK | KMSAN_POISON_FREE); kmsan_leave_runtime(); } @@ -114,7 +115,8 @@ void kmsan_kfree_large(const void *ptr) kmsan_enter_runtime(); page = virt_to_head_page((void *)ptr); KMSAN_WARN_ON(ptr != page_address(page)); - kmsan_internal_poison_memory((void *)ptr, page_size(page), GFP_KERNEL, + kmsan_internal_poison_memory((void *)ptr, page_size(page), + GFP_KERNEL & ~(__GFP_RECLAIM), KMSAN_POISON_CHECK | KMSAN_POISON_FREE); kmsan_leave_runtime(); } --- a/mm/kmsan/shadow.c~mm-kmsan-fix-kmsan-kmalloc-hook-when-no-stack-depots-are-allocated-yet +++ a/mm/kmsan/shadow.c @@ -208,7 +208,7 @@ void kmsan_free_page(struct page *page, return; kmsan_enter_runtime(); kmsan_internal_poison_memory(page_address(page), page_size(page), - GFP_KERNEL, + GFP_KERNEL & ~(__GFP_RECLAIM), KMSAN_POISON_CHECK | KMSAN_POISON_FREE); kmsan_leave_runtime(); } _ Patches currently in -mm which might be from aleksei.nikiforov(a)linux.ibm.com are

2 days, 23 hours

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[merged mm-hotfixes-stable] mm-shmem-fix-thp-allocation-and-fallback-loop.patch removed from -mm tree

by Andrew Morton

The quilt patch titled Subject: mm/shmem: fix THP allocation and fallback loop has been removed from the -mm tree. Its filename was mm-shmem-fix-thp-allocation-and-fallback-loop.patch This patch was dropped because it was merged into the mm-hotfixes-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: Kairui Song <kasong(a)tencent.com> Subject: mm/shmem: fix THP allocation and fallback loop Date: Wed, 22 Oct 2025 18:57:19 +0800 The order check and fallback loop is updating the index value on every loop. This will cause the index to be wrongly aligned by a larger value while the loop shrinks the order. This may result in inserting and returning a folio of the wrong index and cause data corruption with some userspace workloads [1]. [kasong(a)tencent.com: introduce a temporary variable to improve code] Link: https://lkml.kernel.org/r/20251023065913.36925-1-ryncsn@gmail.com Link: https://lore.kernel.org/linux-mm/CAMgjq7DqgAmj25nDUwwu1U2cSGSn8n4-Hqpgotted… [1] Link: https://lkml.kernel.org/r/20251022105719.18321-1-ryncsn@gmail.com Link: https://lore.kernel.org/linux-mm/CAMgjq7DqgAmj25nDUwwu1U2cSGSn8n4-Hqpgotted… [1] Fixes: e7a2ab7b3bb5 ("mm: shmem: add mTHP support for anonymous shmem") Closes: https://lore.kernel.org/linux-mm/CAMgjq7DqgAmj25nDUwwu1U2cSGSn8n4-Hqpgotted… Signed-off-by: Kairui Song <kasong(a)tencent.com> Acked-by: David Hildenbrand <david(a)redhat.com> Acked-by: Zi Yan <ziy(a)nvidia.com> Reviewed-by: Baolin Wang <baolin.wang(a)linux.alibaba.com> Reviewed-by: Barry Song <baohua(a)kernel.org> Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes(a)oracle.com> Cc: Dev Jain <dev.jain(a)arm.com> Cc: Hugh Dickins <hughd(a)google.com> Cc: Liam Howlett <liam.howlett(a)oracle.com> Cc: Matthew Wilcox (Oracle) <willy(a)infradead.org> Cc: Nico Pache <npache(a)redhat.com> Cc: Ryan Roberts <ryan.roberts(a)arm.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/shmem.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) --- a/mm/shmem.c~mm-shmem-fix-thp-allocation-and-fallback-loop +++ a/mm/shmem.c @@ -1882,6 +1882,7 @@ static struct folio *shmem_alloc_and_add struct shmem_inode_info *info = SHMEM_I(inode); unsigned long suitable_orders = 0; struct folio *folio = NULL; + pgoff_t aligned_index; long pages; int error, order; @@ -1895,10 +1896,12 @@ static struct folio *shmem_alloc_and_add order = highest_order(suitable_orders); while (suitable_orders) { pages = 1UL << order; - index = round_down(index, pages); - folio = shmem_alloc_folio(gfp, order, info, index); - if (folio) + aligned_index = round_down(index, pages); + folio = shmem_alloc_folio(gfp, order, info, aligned_index); + if (folio) { + index = aligned_index; goto allocated; + } if (pages == HPAGE_PMD_NR) count_vm_event(THP_FILE_FALLBACK); _ Patches currently in -mm which might be from kasong(a)tencent.com are mm-swap-do-not-perform-synchronous-discard-during-allocation.patch mm-swap-rename-helper-for-setup-bad-slots.patch mm-swap-cleanup-swap-entry-allocation-parameter.patch mm-migrate-swap-drop-usage-of-folio_index.patch mm-swap-remove-redundant-argument-for-isolating-a-cluster.patch revert-mm-swap-avoid-redundant-swap-device-pinning.patch

2 days, 23 hours

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[merged mm-hotfixes-stable] liveupdate-kho-allocate-metadata-directly-from-the-buddy-allocator.patch removed from -mm tree

by Andrew Morton

The quilt patch titled Subject: kho: allocate metadata directly from the buddy allocator has been removed from the -mm tree. Its filename was liveupdate-kho-allocate-metadata-directly-from-the-buddy-allocator.patch This patch was dropped because it was merged into the mm-hotfixes-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: Pasha Tatashin <pasha.tatashin(a)soleen.com> Subject: kho: allocate metadata directly from the buddy allocator Date: Mon, 20 Oct 2025 20:08:52 -0400 KHO allocates metadata for its preserved memory map using the slab allocator via kzalloc(). This metadata is temporary and is used by the next kernel during early boot to find preserved memory. A problem arises when KFENCE is enabled. kzalloc() calls can be randomly intercepted by kfence_alloc(), which services the allocation from a dedicated KFENCE memory pool. This pool is allocated early in boot via memblock. When booting via KHO, the memblock allocator is restricted to a "scratch area", forcing the KFENCE pool to be allocated within it. This creates a conflict, as the scratch area is expected to be ephemeral and overwriteable by a subsequent kexec. If KHO metadata is placed in this KFENCE pool, it leads to memory corruption when the next kernel is loaded. To fix this, modify KHO to allocate its metadata directly from the buddy allocator instead of slab. Link: https://lkml.kernel.org/r/20251021000852.2924827-4-pasha.tatashin@soleen.com Fixes: fc33e4b44b27 ("kexec: enable KHO support for memory preservation") Signed-off-by: Pasha Tatashin <pasha.tatashin(a)soleen.com> Reviewed-by: Pratyush Yadav <pratyush(a)kernel.org> Reviewed-by: Mike Rapoport (Microsoft) <rppt(a)kernel.org> Reviewed-by: David Matlack <dmatlack(a)google.com> Cc: Alexander Graf <graf(a)amazon.com> Cc: Christian Brauner <brauner(a)kernel.org> Cc: Jason Gunthorpe <jgg(a)ziepe.ca> Cc: Jonathan Corbet <corbet(a)lwn.net> Cc: Masahiro Yamada <masahiroy(a)kernel.org> Cc: Miguel Ojeda <ojeda(a)kernel.org> Cc: Randy Dunlap <rdunlap(a)infradead.org> Cc: Samiullah Khawaja <skhawaja(a)google.com> Cc: Tejun Heo <tj(a)kernel.org> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- include/linux/gfp.h | 3 +++ kernel/kexec_handover.c | 6 +++--- 2 files changed, 6 insertions(+), 3 deletions(-) --- a/include/linux/gfp.h~liveupdate-kho-allocate-metadata-directly-from-the-buddy-allocator +++ a/include/linux/gfp.h @@ -7,6 +7,7 @@ #include <linux/mmzone.h> #include <linux/topology.h> #include <linux/alloc_tag.h> +#include <linux/cleanup.h> #include <linux/sched.h> struct vm_area_struct; @@ -463,4 +464,6 @@ static inline struct folio *folio_alloc_ /* This should be paired with folio_put() rather than free_contig_range(). */ #define folio_alloc_gigantic(...) alloc_hooks(folio_alloc_gigantic_noprof(__VA_ARGS__)) +DEFINE_FREE(free_page, void *, free_page((unsigned long)_T)) + #endif /* __LINUX_GFP_H */ --- a/kernel/kexec_handover.c~liveupdate-kho-allocate-metadata-directly-from-the-buddy-allocator +++ a/kernel/kexec_handover.c @@ -142,7 +142,7 @@ static void *xa_load_or_alloc(struct xar if (res) return res; - void *elm __free(kfree) = kzalloc(PAGE_SIZE, GFP_KERNEL); + void *elm __free(free_page) = (void *)get_zeroed_page(GFP_KERNEL); if (!elm) return ERR_PTR(-ENOMEM); @@ -348,9 +348,9 @@ static_assert(sizeof(struct khoser_mem_c static struct khoser_mem_chunk *new_chunk(struct khoser_mem_chunk *cur_chunk, unsigned long order) { - struct khoser_mem_chunk *chunk __free(kfree) = NULL; + struct khoser_mem_chunk *chunk __free(free_page) = NULL; - chunk = kzalloc(PAGE_SIZE, GFP_KERNEL); + chunk = (void *)get_zeroed_page(GFP_KERNEL); if (!chunk) return ERR_PTR(-ENOMEM); _ Patches currently in -mm which might be from pasha.tatashin(a)soleen.com are lib-test_kho-check-if-kho-is-enabled.patch kho-make-debugfs-interface-optional.patch kho-add-interfaces-to-unpreserve-folios-page-ranges-and-vmalloc.patch memblock-unpreserve-memory-in-case-of-error.patch test_kho-unpreserve-memory-in-case-of-error.patch kho-dont-unpreserve-memory-during-abort.patch liveupdate-kho-move-to-kernel-liveupdate.patch liveupdate-kho-move-to-kernel-liveupdate-fix.patch maintainers-update-kho-maintainers.patch liveupdate-luo_core-luo_ioctl-live-update-orchestrator.patch liveupdate-luo_core-integrate-with-kho.patch reboot-call-liveupdate_reboot-before-kexec.patch liveupdate-kconfig-make-debugfs-optional.patch liveupdate-kho-when-live-update-add-kho-image-during-kexec-load.patch liveupdate-luo_session-add-sessions-support.patch liveupdate-luo_ioctl-add-user-interface.patch liveupdate-luo_file-implement-file-systems-callbacks.patch liveupdate-luo_session-add-ioctls-for-file-preservation-and-state-management.patch liveupdate-luo_flb-introduce-file-lifecycle-bound-global-state.patch docs-add-luo-documentation.patch maintainers-add-liveupdate-entry.patch selftests-liveupdate-add-userspace-api-selftests.patch selftests-liveupdate-add-kexec-based-selftest-for-session-lifecycle.patch selftests-liveupdate-add-kexec-test-for-multiple-and-empty-sessions.patch tests-liveupdate-add-in-kernel-liveupdate-test.patch

2 days, 23 hours

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[merged mm-hotfixes-stable] liveupdate-kho-increase-metadata-bitmap-size-to-page_size.patch removed from -mm tree

by Andrew Morton

The quilt patch titled Subject: kho: increase metadata bitmap size to PAGE_SIZE has been removed from the -mm tree. Its filename was liveupdate-kho-increase-metadata-bitmap-size-to-page_size.patch This patch was dropped because it was merged into the mm-hotfixes-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: Pasha Tatashin <pasha.tatashin(a)soleen.com> Subject: kho: increase metadata bitmap size to PAGE_SIZE Date: Mon, 20 Oct 2025 20:08:51 -0400 KHO memory preservation metadata is preserved in 512 byte chunks which requires their allocation from slab allocator. Slabs are not safe to be used with KHO because of kfence, and because partial slabs may lead leaks to the next kernel. Change the size to be PAGE_SIZE. The kfence specifically may cause memory corruption, where it randomly provides slab objects that can be within the scratch area. The reason for that is that kfence allocates its objects prior to KHO scratch is marked as CMA region. While this change could potentially increase metadata overhead on systems with sparsely preserved memory, this is being mitigated by ongoing work to reduce sparseness during preservation via 1G guest pages. Furthermore, this change aligns with future work on a stateless KHO, which will also use page-sized bitmaps for its radix tree metadata. Link: https://lkml.kernel.org/r/20251021000852.2924827-3-pasha.tatashin@soleen.com Fixes: fc33e4b44b27 ("kexec: enable KHO support for memory preservation") Signed-off-by: Pasha Tatashin <pasha.tatashin(a)soleen.com> Reviewed-by: Mike Rapoport (Microsoft) <rppt(a)kernel.org> Reviewed-by: Pratyush Yadav <pratyush(a)kernel.org> Cc: Alexander Graf <graf(a)amazon.com> Cc: Christian Brauner <brauner(a)kernel.org> Cc: David Matlack <dmatlack(a)google.com> Cc: Jason Gunthorpe <jgg(a)ziepe.ca> Cc: Jonathan Corbet <corbet(a)lwn.net> Cc: Masahiro Yamada <masahiroy(a)kernel.org> Cc: Miguel Ojeda <ojeda(a)kernel.org> Cc: Randy Dunlap <rdunlap(a)infradead.org> Cc: Samiullah Khawaja <skhawaja(a)google.com> Cc: Tejun Heo <tj(a)kernel.org> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- kernel/kexec_handover.c | 21 +++++++++++---------- 1 file changed, 11 insertions(+), 10 deletions(-) --- a/kernel/kexec_handover.c~liveupdate-kho-increase-metadata-bitmap-size-to-page_size +++ a/kernel/kexec_handover.c @@ -69,10 +69,10 @@ early_param("kho", kho_parse_enable); * Keep track of memory that is to be preserved across KHO. * * The serializing side uses two levels of xarrays to manage chunks of per-order - * 512 byte bitmaps. For instance if PAGE_SIZE = 4096, the entire 1G order of a - * 1TB system would fit inside a single 512 byte bitmap. For order 0 allocations - * each bitmap will cover 16M of address space. Thus, for 16G of memory at most - * 512K of bitmap memory will be needed for order 0. + * PAGE_SIZE byte bitmaps. For instance if PAGE_SIZE = 4096, the entire 1G order + * of a 8TB system would fit inside a single 4096 byte bitmap. For order 0 + * allocations each bitmap will cover 128M of address space. Thus, for 16G of + * memory at most 512K of bitmap memory will be needed for order 0. * * This approach is fully incremental, as the serialization progresses folios * can continue be aggregated to the tracker. The final step, immediately prior @@ -80,12 +80,14 @@ early_param("kho", kho_parse_enable); * successor kernel to parse. */ -#define PRESERVE_BITS (512 * 8) +#define PRESERVE_BITS (PAGE_SIZE * 8) struct kho_mem_phys_bits { DECLARE_BITMAP(preserve, PRESERVE_BITS); }; +static_assert(sizeof(struct kho_mem_phys_bits) == PAGE_SIZE); + struct kho_mem_phys { /* * Points to kho_mem_phys_bits, a sparse bitmap array. Each bit is sized @@ -133,19 +135,19 @@ static struct kho_out kho_out = { .finalized = false, }; -static void *xa_load_or_alloc(struct xarray *xa, unsigned long index, size_t sz) +static void *xa_load_or_alloc(struct xarray *xa, unsigned long index) { void *res = xa_load(xa, index); if (res) return res; - void *elm __free(kfree) = kzalloc(sz, GFP_KERNEL); + void *elm __free(kfree) = kzalloc(PAGE_SIZE, GFP_KERNEL); if (!elm) return ERR_PTR(-ENOMEM); - if (WARN_ON(kho_scratch_overlap(virt_to_phys(elm), sz))) + if (WARN_ON(kho_scratch_overlap(virt_to_phys(elm), PAGE_SIZE))) return ERR_PTR(-EINVAL); res = xa_cmpxchg(xa, index, NULL, elm, GFP_KERNEL); @@ -218,8 +220,7 @@ static int __kho_preserve_order(struct k } } - bits = xa_load_or_alloc(&physxa->phys_bits, pfn_high / PRESERVE_BITS, - sizeof(*bits)); + bits = xa_load_or_alloc(&physxa->phys_bits, pfn_high / PRESERVE_BITS); if (IS_ERR(bits)) return PTR_ERR(bits); _ Patches currently in -mm which might be from pasha.tatashin(a)soleen.com are lib-test_kho-check-if-kho-is-enabled.patch kho-make-debugfs-interface-optional.patch kho-add-interfaces-to-unpreserve-folios-page-ranges-and-vmalloc.patch memblock-unpreserve-memory-in-case-of-error.patch test_kho-unpreserve-memory-in-case-of-error.patch kho-dont-unpreserve-memory-during-abort.patch liveupdate-kho-move-to-kernel-liveupdate.patch liveupdate-kho-move-to-kernel-liveupdate-fix.patch maintainers-update-kho-maintainers.patch liveupdate-luo_core-luo_ioctl-live-update-orchestrator.patch liveupdate-luo_core-integrate-with-kho.patch reboot-call-liveupdate_reboot-before-kexec.patch liveupdate-kconfig-make-debugfs-optional.patch liveupdate-kho-when-live-update-add-kho-image-during-kexec-load.patch liveupdate-luo_session-add-sessions-support.patch liveupdate-luo_ioctl-add-user-interface.patch liveupdate-luo_file-implement-file-systems-callbacks.patch liveupdate-luo_session-add-ioctls-for-file-preservation-and-state-management.patch liveupdate-luo_flb-introduce-file-lifecycle-bound-global-state.patch docs-add-luo-documentation.patch maintainers-add-liveupdate-entry.patch selftests-liveupdate-add-userspace-api-selftests.patch selftests-liveupdate-add-kexec-based-selftest-for-session-lifecycle.patch selftests-liveupdate-add-kexec-test-for-multiple-and-empty-sessions.patch tests-liveupdate-add-in-kernel-liveupdate-test.patch

2 days, 23 hours

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[merged mm-hotfixes-stable] liveupdate-kho-warn-and-fail-on-metadata-or-preserved-memory-in-scratch-area.patch removed from -mm tree

by Andrew Morton

The quilt patch titled Subject: kho: warn and fail on metadata or preserved memory in scratch area has been removed from the -mm tree. Its filename was liveupdate-kho-warn-and-fail-on-metadata-or-preserved-memory-in-scratch-area.patch This patch was dropped because it was merged into the mm-hotfixes-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: Pasha Tatashin <pasha.tatashin(a)soleen.com> Subject: kho: warn and fail on metadata or preserved memory in scratch area Date: Mon, 20 Oct 2025 20:08:50 -0400 Patch series "KHO: kfence + KHO memory corruption fix", v3. This series fixes a memory corruption bug in KHO that occurs when KFENCE is enabled. The root cause is that KHO metadata, allocated via kzalloc(), can be randomly serviced by kfence_alloc(). When a kernel boots via KHO, the early memblock allocator is restricted to a "scratch area". This forces the KFENCE pool to be allocated within this scratch area, creating a conflict. If KHO metadata is subsequently placed in this pool, it gets corrupted during the next kexec operation. Google is using KHO and have had obscure crashes due to this memory corruption, with stacks all over the place. I would prefer this fix to be properly backported to stable so we can also automatically consume it once we switch to the upstream KHO. Patch 1/3 introduces a debug-only feature (CONFIG_KEXEC_HANDOVER_DEBUG) that adds checks to detect and fail any operation that attempts to place KHO metadata or preserved memory within the scratch area. This serves as a validation and diagnostic tool to confirm the problem without affecting production builds. Patch 2/3 Increases bitmap to PAGE_SIZE, so buddy allocator can be used. Patch 3/3 Provides the fix by modifying KHO to allocate its metadata directly from the buddy allocator instead of slab. This bypasses the KFENCE interception entirely. This patch (of 3): It is invalid for KHO metadata or preserved memory regions to be located within the KHO scratch area, as this area is overwritten when the next kernel is loaded, and used early in boot by the next kernel. This can lead to memory corruption. Add checks to kho_preserve_* and KHO's internal metadata allocators (xa_load_or_alloc, new_chunk) to verify that the physical address of the memory does not overlap with any defined scratch region. If an overlap is detected, the operation will fail and a WARN_ON is triggered. To avoid performance overhead in production kernels, these checks are enabled only when CONFIG_KEXEC_HANDOVER_DEBUG is selected. [rppt(a)kernel.org: fix KEXEC_HANDOVER_DEBUG Kconfig dependency] Link: https://lkml.kernel.org/r/aQHUyyFtiNZhx8jo@kernel.org [pasha.tatashin(a)soleen.com: build fix] Link: https://lkml.kernel.org/r/CA+CK2bBnorfsTymKtv4rKvqGBHs=y=MjEMMRg_tE-RME6n-z… Link: https://lkml.kernel.org/r/20251021000852.2924827-1-pasha.tatashin@soleen.com Link: https://lkml.kernel.org/r/20251021000852.2924827-2-pasha.tatashin@soleen.com Fixes: fc33e4b44b27 ("kexec: enable KHO support for memory preservation") Signed-off-by: Pasha Tatashin <pasha.tatashin(a)soleen.com> Signed-off-by: Mike Rapoport <rppt(a)kernel.org> Reviewed-by: Mike Rapoport (Microsoft) <rppt(a)kernel.org> Reviewed-by: Pratyush Yadav <pratyush(a)kernel.org> Cc: Alexander Graf <graf(a)amazon.com> Cc: Christian Brauner <brauner(a)kernel.org> Cc: David Matlack <dmatlack(a)google.com> Cc: Jason Gunthorpe <jgg(a)ziepe.ca> Cc: Jonathan Corbet <corbet(a)lwn.net> Cc: Masahiro Yamada <masahiroy(a)kernel.org> Cc: Miguel Ojeda <ojeda(a)kernel.org> Cc: Randy Dunlap <rdunlap(a)infradead.org> Cc: Samiullah Khawaja <skhawaja(a)google.com> Cc: Tejun Heo <tj(a)kernel.org> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- kernel/Kconfig.kexec | 9 ++++ kernel/Makefile | 1 kernel/kexec_handover.c | 57 +++++++++++++++++++---------- kernel/kexec_handover_debug.c | 25 ++++++++++++ kernel/kexec_handover_internal.h | 20 ++++++++++ 5 files changed, 93 insertions(+), 19 deletions(-) --- a/kernel/Kconfig.kexec~liveupdate-kho-warn-and-fail-on-metadata-or-preserved-memory-in-scratch-area +++ a/kernel/Kconfig.kexec @@ -109,6 +109,15 @@ config KEXEC_HANDOVER to keep data or state alive across the kexec. For this to work, both source and target kernels need to have this option enabled. +config KEXEC_HANDOVER_DEBUG + bool "Enable Kexec Handover debug checks" + depends on KEXEC_HANDOVER + help + This option enables extra sanity checks for the Kexec Handover + subsystem. Since, KHO performance is crucial in live update + scenarios and the extra code might be adding overhead it is + only optionally enabled. + config CRASH_DUMP bool "kernel crash dumps" default ARCH_DEFAULT_CRASH_DUMP --- a/kernel/kexec_handover.c~liveupdate-kho-warn-and-fail-on-metadata-or-preserved-memory-in-scratch-area +++ a/kernel/kexec_handover.c @@ -8,6 +8,7 @@ #define pr_fmt(fmt) "KHO: " fmt +#include <linux/cleanup.h> #include <linux/cma.h> #include <linux/count_zeros.h> #include <linux/debugfs.h> @@ -22,6 +23,7 @@ #include <asm/early_ioremap.h> +#include "kexec_handover_internal.h" /* * KHO is tightly coupled with mm init and needs access to some of mm * internal APIs. @@ -133,26 +135,26 @@ static struct kho_out kho_out = { static void *xa_load_or_alloc(struct xarray *xa, unsigned long index, size_t sz) { - void *elm, *res; + void *res = xa_load(xa, index); - elm = xa_load(xa, index); - if (elm) - return elm; + if (res) + return res; + + void *elm __free(kfree) = kzalloc(sz, GFP_KERNEL); - elm = kzalloc(sz, GFP_KERNEL); if (!elm) return ERR_PTR(-ENOMEM); + if (WARN_ON(kho_scratch_overlap(virt_to_phys(elm), sz))) + return ERR_PTR(-EINVAL); + res = xa_cmpxchg(xa, index, NULL, elm, GFP_KERNEL); if (xa_is_err(res)) - res = ERR_PTR(xa_err(res)); - - if (res) { - kfree(elm); + return ERR_PTR(xa_err(res)); + else if (res) return res; - } - return elm; + return no_free_ptr(elm); } static void __kho_unpreserve(struct kho_mem_track *track, unsigned long pfn, @@ -345,15 +347,19 @@ static_assert(sizeof(struct khoser_mem_c static struct khoser_mem_chunk *new_chunk(struct khoser_mem_chunk *cur_chunk, unsigned long order) { - struct khoser_mem_chunk *chunk; + struct khoser_mem_chunk *chunk __free(kfree) = NULL; chunk = kzalloc(PAGE_SIZE, GFP_KERNEL); if (!chunk) - return NULL; + return ERR_PTR(-ENOMEM); + + if (WARN_ON(kho_scratch_overlap(virt_to_phys(chunk), PAGE_SIZE))) + return ERR_PTR(-EINVAL); + chunk->hdr.order = order; if (cur_chunk) KHOSER_STORE_PTR(cur_chunk->hdr.next, chunk); - return chunk; + return no_free_ptr(chunk); } static void kho_mem_ser_free(struct khoser_mem_chunk *first_chunk) @@ -374,14 +380,17 @@ static int kho_mem_serialize(struct kho_ struct khoser_mem_chunk *chunk = NULL; struct kho_mem_phys *physxa; unsigned long order; + int err = -ENOMEM; xa_for_each(&ser->track.orders, order, physxa) { struct kho_mem_phys_bits *bits; unsigned long phys; chunk = new_chunk(chunk, order); - if (!chunk) + if (IS_ERR(chunk)) { + err = PTR_ERR(chunk); goto err_free; + } if (!first_chunk) first_chunk = chunk; @@ -391,8 +400,10 @@ static int kho_mem_serialize(struct kho_ if (chunk->hdr.num_elms == ARRAY_SIZE(chunk->bitmaps)) { chunk = new_chunk(chunk, order); - if (!chunk) + if (IS_ERR(chunk)) { + err = PTR_ERR(chunk); goto err_free; + } } elm = &chunk->bitmaps[chunk->hdr.num_elms]; @@ -409,7 +420,7 @@ static int kho_mem_serialize(struct kho_ err_free: kho_mem_ser_free(first_chunk); - return -ENOMEM; + return err; } static void __init deserialize_bitmap(unsigned int order, @@ -465,8 +476,8 @@ static void __init kho_mem_deserialize(c * area for early allocations that happen before page allocator is * initialized. */ -static struct kho_scratch *kho_scratch; -static unsigned int kho_scratch_cnt; +struct kho_scratch *kho_scratch; +unsigned int kho_scratch_cnt; /* * The scratch areas are scaled by default as percent of memory allocated from @@ -752,6 +763,9 @@ int kho_preserve_folio(struct folio *fol const unsigned int order = folio_order(folio); struct kho_mem_track *track = &kho_out.ser.track; + if (WARN_ON(kho_scratch_overlap(pfn << PAGE_SHIFT, PAGE_SIZE << order))) + return -EINVAL; + return __kho_preserve_order(track, pfn, order); } EXPORT_SYMBOL_GPL(kho_preserve_folio); @@ -775,6 +789,11 @@ int kho_preserve_pages(struct page *page unsigned long failed_pfn = 0; int err = 0; + if (WARN_ON(kho_scratch_overlap(start_pfn << PAGE_SHIFT, + nr_pages << PAGE_SHIFT))) { + return -EINVAL; + } + while (pfn < end_pfn) { const unsigned int order = min(count_trailing_zeros(pfn), ilog2(end_pfn - pfn)); diff --git a/kernel/kexec_handover_debug.c a/kernel/kexec_handover_debug.c new file mode 100644 --- /dev/null +++ a/kernel/kexec_handover_debug.c @@ -0,0 +1,25 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * kexec_handover_debug.c - kexec handover optional debug functionality + * Copyright (C) 2025 Google LLC, Pasha Tatashin <pasha.tatashin(a)soleen.com> + */ + +#define pr_fmt(fmt) "KHO: " fmt + +#include "kexec_handover_internal.h" + +bool kho_scratch_overlap(phys_addr_t phys, size_t size) +{ + phys_addr_t scratch_start, scratch_end; + unsigned int i; + + for (i = 0; i < kho_scratch_cnt; i++) { + scratch_start = kho_scratch[i].addr; + scratch_end = kho_scratch[i].addr + kho_scratch[i].size; + + if (phys < scratch_end && (phys + size) > scratch_start) + return true; + } + + return false; +} diff --git a/kernel/kexec_handover_internal.h a/kernel/kexec_handover_internal.h new file mode 100644 --- /dev/null +++ a/kernel/kexec_handover_internal.h @@ -0,0 +1,20 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef LINUX_KEXEC_HANDOVER_INTERNAL_H +#define LINUX_KEXEC_HANDOVER_INTERNAL_H + +#include <linux/kexec_handover.h> +#include <linux/types.h> + +extern struct kho_scratch *kho_scratch; +extern unsigned int kho_scratch_cnt; + +#ifdef CONFIG_KEXEC_HANDOVER_DEBUG +bool kho_scratch_overlap(phys_addr_t phys, size_t size); +#else +static inline bool kho_scratch_overlap(phys_addr_t phys, size_t size) +{ + return false; +} +#endif /* CONFIG_KEXEC_HANDOVER_DEBUG */ + +#endif /* LINUX_KEXEC_HANDOVER_INTERNAL_H */ --- a/kernel/Makefile~liveupdate-kho-warn-and-fail-on-metadata-or-preserved-memory-in-scratch-area +++ a/kernel/Makefile @@ -83,6 +83,7 @@ obj-$(CONFIG_KEXEC) += kexec.o obj-$(CONFIG_KEXEC_FILE) += kexec_file.o obj-$(CONFIG_KEXEC_ELF) += kexec_elf.o obj-$(CONFIG_KEXEC_HANDOVER) += kexec_handover.o +obj-$(CONFIG_KEXEC_HANDOVER_DEBUG) += kexec_handover_debug.o obj-$(CONFIG_BACKTRACE_SELF_TEST) += backtracetest.o obj-$(CONFIG_COMPAT) += compat.o obj-$(CONFIG_CGROUPS) += cgroup/ _ Patches currently in -mm which might be from pasha.tatashin(a)soleen.com are lib-test_kho-check-if-kho-is-enabled.patch kho-make-debugfs-interface-optional.patch kho-add-interfaces-to-unpreserve-folios-page-ranges-and-vmalloc.patch memblock-unpreserve-memory-in-case-of-error.patch test_kho-unpreserve-memory-in-case-of-error.patch kho-dont-unpreserve-memory-during-abort.patch liveupdate-kho-move-to-kernel-liveupdate.patch liveupdate-kho-move-to-kernel-liveupdate-fix.patch maintainers-update-kho-maintainers.patch liveupdate-luo_core-luo_ioctl-live-update-orchestrator.patch liveupdate-luo_core-integrate-with-kho.patch reboot-call-liveupdate_reboot-before-kexec.patch liveupdate-kconfig-make-debugfs-optional.patch liveupdate-kho-when-live-update-add-kho-image-during-kexec-load.patch liveupdate-luo_session-add-sessions-support.patch liveupdate-luo_ioctl-add-user-interface.patch liveupdate-luo_file-implement-file-systems-callbacks.patch liveupdate-luo_session-add-ioctls-for-file-preservation-and-state-management.patch liveupdate-luo_flb-introduce-file-lifecycle-bound-global-state.patch docs-add-luo-documentation.patch maintainers-add-liveupdate-entry.patch selftests-liveupdate-add-userspace-api-selftests.patch selftests-liveupdate-add-kexec-based-selftest-for-session-lifecycle.patch selftests-liveupdate-add-kexec-test-for-multiple-and-empty-sessions.patch tests-liveupdate-add-in-kernel-liveupdate-test.patch

2 days, 23 hours

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[merged mm-hotfixes-stable] mm-huge_memory-do-not-change-split_huge_page-target-order-silently.patch removed from -mm tree

by Andrew Morton

The quilt patch titled Subject: mm/huge_memory: do not change split_huge_page*() target order silently has been removed from the -mm tree. Its filename was mm-huge_memory-do-not-change-split_huge_page-target-order-silently.patch This patch was dropped because it was merged into the mm-hotfixes-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: Zi Yan <ziy(a)nvidia.com> Subject: mm/huge_memory: do not change split_huge_page*() target order silently Date: Thu, 16 Oct 2025 21:36:30 -0400 Page cache folios from a file system that support large block size (LBS) can have minimal folio order greater than 0, thus a high order folio might not be able to be split down to order-0. Commit e220917fa507 ("mm: split a folio in minimum folio order chunks") bumps the target order of split_huge_page*() to the minimum allowed order when splitting a LBS folio. This causes confusion for some split_huge_page*() callers like memory failure handling code, since they expect after-split folios all have order-0 when split succeeds but in reality get min_order_for_split() order folios and give warnings. Fix it by failing a split if the folio cannot be split to the target order. Rename try_folio_split() to try_folio_split_to_order() to reflect the added new_order parameter. Remove its unused list parameter. [The test poisons LBS folios, which cannot be split to order-0 folios, and also tries to poison all memory. The non split LBS folios take more memory than the test anticipated, leading to OOM. The patch fixed the kernel warning and the test needs some change to avoid OOM.] Link: https://lkml.kernel.org/r/20251017013630.139907-1-ziy@nvidia.com Fixes: e220917fa507 ("mm: split a folio in minimum folio order chunks") Signed-off-by: Zi Yan <ziy(a)nvidia.com> Reported-by: syzbot+e6367ea2fdab6ed46056(a)syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/68d2c943.a70a0220.1b52b.02b3.GAE@google.com/ Reviewed-by: Luis Chamberlain <mcgrof(a)kernel.org> Reviewed-by: Pankaj Raghav <p.raghav(a)samsung.com> Reviewed-by: Wei Yang <richard.weiyang(a)gmail.com> Acked-by: David Hildenbrand <david(a)redhat.com> Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes(a)oracle.com> Reviewed-by: Miaohe Lin <linmiaohe(a)huawei.com> Cc: Baolin Wang <baolin.wang(a)linux.alibaba.com> Cc: Barry Song <baohua(a)kernel.org> Cc: David Hildenbrand <david(a)redhat.com> Cc: Dev Jain <dev.jain(a)arm.com> Cc: Jane Chu <jane.chu(a)oracle.com> Cc: Lance Yang <lance.yang(a)linux.dev> Cc: Liam Howlett <liam.howlett(a)oracle.com> Cc: Mariano Pache <npache(a)redhat.com> Cc: Matthew Wilcox (Oracle) <willy(a)infradead.org> Cc: Naoya Horiguchi <nao.horiguchi(a)gmail.com> Cc: Ryan Roberts <ryan.roberts(a)arm.com> Cc: Christian Brauner <brauner(a)kernel.org> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- include/linux/huge_mm.h | 55 +++++++++++++++----------------------- mm/huge_memory.c | 9 ------ mm/truncate.c | 6 ++-- 3 files changed, 28 insertions(+), 42 deletions(-) --- a/include/linux/huge_mm.h~mm-huge_memory-do-not-change-split_huge_page-target-order-silently +++ a/include/linux/huge_mm.h @@ -376,45 +376,30 @@ bool non_uniform_split_supported(struct int folio_split(struct folio *folio, unsigned int new_order, struct page *page, struct list_head *list); /* - * try_folio_split - try to split a @folio at @page using non uniform split. + * try_folio_split_to_order - try to split a @folio at @page to @new_order using + * non uniform split. * @folio: folio to be split - * @page: split to order-0 at the given page - * @list: store the after-split folios + * @page: split to @new_order at the given page + * @new_order: the target split order * - * Try to split a @folio at @page using non uniform split to order-0, if - * non uniform split is not supported, fall back to uniform split. + * Try to split a @folio at @page using non uniform split to @new_order, if + * non uniform split is not supported, fall back to uniform split. After-split + * folios are put back to LRU list. Use min_order_for_split() to get the lower + * bound of @new_order. * * Return: 0: split is successful, otherwise split failed. */ -static inline int try_folio_split(struct folio *folio, struct page *page, - struct list_head *list) +static inline int try_folio_split_to_order(struct folio *folio, + struct page *page, unsigned int new_order) { - int ret = min_order_for_split(folio); - - if (ret < 0) - return ret; - - if (!non_uniform_split_supported(folio, 0, false)) - return split_huge_page_to_list_to_order(&folio->page, list, - ret); - return folio_split(folio, ret, page, list); + if (!non_uniform_split_supported(folio, new_order, /* warns= */ false)) + return split_huge_page_to_list_to_order(&folio->page, NULL, + new_order); + return folio_split(folio, new_order, page, NULL); } static inline int split_huge_page(struct page *page) { - struct folio *folio = page_folio(page); - int ret = min_order_for_split(folio); - - if (ret < 0) - return ret; - - /* - * split_huge_page() locks the page before splitting and - * expects the same page that has been split to be locked when - * returned. split_folio(page_folio(page)) cannot be used here - * because it converts the page to folio and passes the head - * page to be split. - */ - return split_huge_page_to_list_to_order(page, NULL, ret); + return split_huge_page_to_list_to_order(page, NULL, 0); } void deferred_split_folio(struct folio *folio, bool partially_mapped); @@ -597,14 +582,20 @@ static inline int split_huge_page(struct return -EINVAL; } +static inline int min_order_for_split(struct folio *folio) +{ + VM_WARN_ON_ONCE_FOLIO(1, folio); + return -EINVAL; +} + static inline int split_folio_to_list(struct folio *folio, struct list_head *list) { VM_WARN_ON_ONCE_FOLIO(1, folio); return -EINVAL; } -static inline int try_folio_split(struct folio *folio, struct page *page, - struct list_head *list) +static inline int try_folio_split_to_order(struct folio *folio, + struct page *page, unsigned int new_order) { VM_WARN_ON_ONCE_FOLIO(1, folio); return -EINVAL; --- a/mm/huge_memory.c~mm-huge_memory-do-not-change-split_huge_page-target-order-silently +++ a/mm/huge_memory.c @@ -3653,8 +3653,6 @@ static int __folio_split(struct folio *f min_order = mapping_min_folio_order(folio->mapping); if (new_order < min_order) { - VM_WARN_ONCE(1, "Cannot split mapped folio below min-order: %u", - min_order); ret = -EINVAL; goto out; } @@ -3986,12 +3984,7 @@ int min_order_for_split(struct folio *fo int split_folio_to_list(struct folio *folio, struct list_head *list) { - int ret = min_order_for_split(folio); - - if (ret < 0) - return ret; - - return split_huge_page_to_list_to_order(&folio->page, list, ret); + return split_huge_page_to_list_to_order(&folio->page, list, 0); } /* --- a/mm/truncate.c~mm-huge_memory-do-not-change-split_huge_page-target-order-silently +++ a/mm/truncate.c @@ -194,6 +194,7 @@ bool truncate_inode_partial_folio(struct size_t size = folio_size(folio); unsigned int offset, length; struct page *split_at, *split_at2; + unsigned int min_order; if (pos < start) offset = start - pos; @@ -223,8 +224,9 @@ bool truncate_inode_partial_folio(struct if (!folio_test_large(folio)) return true; + min_order = mapping_min_folio_order(folio->mapping); split_at = folio_page(folio, PAGE_ALIGN_DOWN(offset) / PAGE_SIZE); - if (!try_folio_split(folio, split_at, NULL)) { + if (!try_folio_split_to_order(folio, split_at, min_order)) { /* * try to split at offset + length to make sure folios within * the range can be dropped, especially to avoid memory waste @@ -254,7 +256,7 @@ bool truncate_inode_partial_folio(struct */ if (folio_test_large(folio2) && folio2->mapping == folio->mapping) - try_folio_split(folio2, split_at2, NULL); + try_folio_split_to_order(folio2, split_at2, min_order); folio_unlock(folio2); out: _ Patches currently in -mm which might be from ziy(a)nvidia.com are mm-huge_memory-fix-folio-split-check-for-anon-folios-in-swapcache.patch mm-huge_memory-add-split_huge_page_to_order.patch mm-memory-failure-improve-large-block-size-folio-handling.patch mm-huge_memory-fix-kernel-doc-comments-for-folio_split-and-related.patch mm-huge_memory-fix-kernel-doc-comments-for-folio_split-and-related-fix.patch mm-huge_memory-fix-kernel-doc-comments-for-folio_split-and-related-fix-2.patch migrate-optimise-alloc_migration_target-fix.patch

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