July 2024 - Linux-stable-mirror

[merged mm-hotfixes-stable] nilfs2-fix-kernel-bug-on-rename-operation-of-broken-directory.patch removed from -mm tree

by Andrew Morton

The quilt patch titled Subject: nilfs2: fix kernel bug on rename operation of broken directory has been removed from the -mm tree. Its filename was nilfs2-fix-kernel-bug-on-rename-operation-of-broken-directory.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: Ryusuke Konishi <konishi.ryusuke(a)gmail.com> Subject: nilfs2: fix kernel bug on rename operation of broken directory Date: Sat, 29 Jun 2024 01:51:07 +0900 Syzbot reported that in rename directory operation on broken directory on nilfs2, __block_write_begin_int() called to prepare block write may fail BUG_ON check for access exceeding the folio/page size. This is because nilfs_dotdot(), which gets parent directory reference entry ("..") of the directory to be moved or renamed, does not check consistency enough, and may return location exceeding folio/page size for broken directories. Fix this issue by checking required directory entries ("." and "..") in the first chunk of the directory in nilfs_dotdot(). Link: https://lkml.kernel.org/r/20240628165107.9006-1-konishi.ryusuke@gmail.com Signed-off-by: Ryusuke Konishi <konishi.ryusuke(a)gmail.com> Reported-by: syzbot+d3abed1ad3d367fa2627(a)syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=d3abed1ad3d367fa2627 Fixes: 2ba466d74ed7 ("nilfs2: directory entry operations") Tested-by: Ryusuke Konishi <konishi.ryusuke(a)gmail.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- fs/nilfs2/dir.c | 32 ++++++++++++++++++++++++++++++-- 1 file changed, 30 insertions(+), 2 deletions(-) --- a/fs/nilfs2/dir.c~nilfs2-fix-kernel-bug-on-rename-operation-of-broken-directory +++ a/fs/nilfs2/dir.c @@ -383,11 +383,39 @@ found: struct nilfs_dir_entry *nilfs_dotdot(struct inode *dir, struct folio **foliop) { - struct nilfs_dir_entry *de = nilfs_get_folio(dir, 0, foliop); + struct folio *folio; + struct nilfs_dir_entry *de, *next_de; + size_t limit; + char *msg; + de = nilfs_get_folio(dir, 0, &folio); if (IS_ERR(de)) return NULL; - return nilfs_next_entry(de); + + limit = nilfs_last_byte(dir, 0); /* is a multiple of chunk size */ + if (unlikely(!limit || le64_to_cpu(de->inode) != dir->i_ino || + !nilfs_match(1, ".", de))) { + msg = "missing '.'"; + goto fail; + } + + next_de = nilfs_next_entry(de); + /* + * If "next_de" has not reached the end of the chunk, there is + * at least one more record. Check whether it matches "..". + */ + if (unlikely((char *)next_de == (char *)de + nilfs_chunk_size(dir) || + !nilfs_match(2, "..", next_de))) { + msg = "missing '..'"; + goto fail; + } + *foliop = folio; + return next_de; + +fail: + nilfs_error(dir->i_sb, "directory #%lu %s", dir->i_ino, msg); + folio_release_kmap(folio, de); + return NULL; } ino_t nilfs_inode_by_name(struct inode *dir, const struct qstr *qstr) _ Patches currently in -mm which might be from konishi.ryusuke(a)gmail.com are nilfs2-avoid-undefined-behavior-in-nilfs_cnt32_ge-macro.patch

5 months, 3 weeks

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[merged mm-hotfixes-stable] cachestat-do-not-flush-stats-in-recency-check.patch removed from -mm tree

by Andrew Morton

The quilt patch titled Subject: cachestat: do not flush stats in recency check has been removed from the -mm tree. Its filename was cachestat-do-not-flush-stats-in-recency-check.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: Nhat Pham <nphamcs(a)gmail.com> Subject: cachestat: do not flush stats in recency check Date: Thu, 27 Jun 2024 13:17:37 -0700 syzbot detects that cachestat() is flushing stats, which can sleep, in its RCU read section (see [1]). This is done in the workingset_test_recent() step (which checks if the folio's eviction is recent). Move the stat flushing step to before the RCU read section of cachestat, and skip stat flushing during the recency check. [1]: https://lore.kernel.org/cgroups/000000000000f71227061bdf97e0@google.com/ Link: https://lkml.kernel.org/r/20240627201737.3506959-1-nphamcs@gmail.com Fixes: b00684722262 ("mm: workingset: move the stats flush into workingset_test_recent()") Signed-off-by: Nhat Pham <nphamcs(a)gmail.com> Reported-by: syzbot+b7f13b2d0cc156edf61a(a)syzkaller.appspotmail.com Closes: https://lore.kernel.org/cgroups/000000000000f71227061bdf97e0@google.com/ Debugged-by: Johannes Weiner <hannes(a)cmpxchg.org> Suggested-by: Johannes Weiner <hannes(a)cmpxchg.org> Acked-by: Johannes Weiner <hannes(a)cmpxchg.org> Acked-by: Shakeel Butt <shakeel.butt(a)linux.dev> Cc: Al Viro <viro(a)zeniv.linux.org.uk> Cc: David Hildenbrand <david(a)redhat.com> Cc: "Huang, Ying" <ying.huang(a)intel.com> Cc: Kairui Song <kasong(a)tencent.com> Cc: Matthew Wilcox (Oracle) <willy(a)infradead.org> Cc: Ryan Roberts <ryan.roberts(a)arm.com> Cc: Yosry Ahmed <yosryahmed(a)google.com> Cc: <stable(a)vger.kernel.org> [6.8+] Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- include/linux/swap.h | 3 ++- mm/filemap.c | 5 ++++- mm/workingset.c | 14 +++++++++++--- 3 files changed, 17 insertions(+), 5 deletions(-) --- a/include/linux/swap.h~cachestat-do-not-flush-stats-in-recency-check +++ a/include/linux/swap.h @@ -354,7 +354,8 @@ static inline swp_entry_t page_swap_entr } /* linux/mm/workingset.c */ -bool workingset_test_recent(void *shadow, bool file, bool *workingset); +bool workingset_test_recent(void *shadow, bool file, bool *workingset, + bool flush); void workingset_age_nonresident(struct lruvec *lruvec, unsigned long nr_pages); void *workingset_eviction(struct folio *folio, struct mem_cgroup *target_memcg); void workingset_refault(struct folio *folio, void *shadow); --- a/mm/filemap.c~cachestat-do-not-flush-stats-in-recency-check +++ a/mm/filemap.c @@ -4248,6 +4248,9 @@ static void filemap_cachestat(struct add XA_STATE(xas, &mapping->i_pages, first_index); struct folio *folio; + /* Flush stats (and potentially sleep) outside the RCU read section. */ + mem_cgroup_flush_stats_ratelimited(NULL); + rcu_read_lock(); xas_for_each(&xas, folio, last_index) { int order; @@ -4311,7 +4314,7 @@ static void filemap_cachestat(struct add goto resched; } #endif - if (workingset_test_recent(shadow, true, &workingset)) + if (workingset_test_recent(shadow, true, &workingset, false)) cs->nr_recently_evicted += nr_pages; goto resched; --- a/mm/workingset.c~cachestat-do-not-flush-stats-in-recency-check +++ a/mm/workingset.c @@ -412,10 +412,12 @@ void *workingset_eviction(struct folio * * @file: whether the corresponding folio is from the file lru. * @workingset: where the workingset value unpacked from shadow should * be stored. + * @flush: whether to flush cgroup rstat. * * Return: true if the shadow is for a recently evicted folio; false otherwise. */ -bool workingset_test_recent(void *shadow, bool file, bool *workingset) +bool workingset_test_recent(void *shadow, bool file, bool *workingset, + bool flush) { struct mem_cgroup *eviction_memcg; struct lruvec *eviction_lruvec; @@ -467,10 +469,16 @@ bool workingset_test_recent(void *shadow /* * Flush stats (and potentially sleep) outside the RCU read section. + * + * Note that workingset_test_recent() itself might be called in RCU read + * section (for e.g, in cachestat) - these callers need to skip flushing + * stats (via the flush argument). + * * XXX: With per-memcg flushing and thresholding, is ratelimiting * still needed here? */ - mem_cgroup_flush_stats_ratelimited(eviction_memcg); + if (flush) + mem_cgroup_flush_stats_ratelimited(eviction_memcg); eviction_lruvec = mem_cgroup_lruvec(eviction_memcg, pgdat); refault = atomic_long_read(&eviction_lruvec->nonresident_age); @@ -558,7 +566,7 @@ void workingset_refault(struct folio *fo mod_lruvec_state(lruvec, WORKINGSET_REFAULT_BASE + file, nr); - if (!workingset_test_recent(shadow, file, &workingset)) + if (!workingset_test_recent(shadow, file, &workingset, true)) return; folio_set_active(folio); _ Patches currently in -mm which might be from nphamcs(a)gmail.com are

5 months, 3 weeks

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[merged mm-hotfixes-stable] mm-shmem-disable-pmd-sized-page-cache-if-needed.patch removed from -mm tree

by Andrew Morton

The quilt patch titled Subject: mm/shmem: disable PMD-sized page cache if needed has been removed from the -mm tree. Its filename was mm-shmem-disable-pmd-sized-page-cache-if-needed.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: Gavin Shan <gshan(a)redhat.com> Subject: mm/shmem: disable PMD-sized page cache if needed Date: Thu, 27 Jun 2024 10:39:52 +1000 For shmem files, it's possible that PMD-sized page cache can't be supported by xarray. For example, 512MB page cache on ARM64 when the base page size is 64KB can't be supported by xarray. It leads to errors as the following messages indicate when this sort of xarray entry is split. WARNING: CPU: 34 PID: 7578 at lib/xarray.c:1025 xas_split_alloc+0xf8/0x128 Modules linked in: binfmt_misc nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 \ nft_fib nft_reject_inet nf_reject_ipv4 nf_reject_ipv6 nft_reject \ nft_ct nft_chain_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 \ ip_set rfkill nf_tables nfnetlink vfat fat virtio_balloon drm fuse xfs \ libcrc32c crct10dif_ce ghash_ce sha2_ce sha256_arm64 sha1_ce virtio_net \ net_failover virtio_console virtio_blk failover dimlib virtio_mmio CPU: 34 PID: 7578 Comm: test Kdump: loaded Tainted: G W 6.10.0-rc5-gavin+ #9 Hardware name: QEMU KVM Virtual Machine, BIOS edk2-20240524-1.el9 05/24/2024 pstate: 83400005 (Nzcv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--) pc : xas_split_alloc+0xf8/0x128 lr : split_huge_page_to_list_to_order+0x1c4/0x720 sp : ffff8000882af5f0 x29: ffff8000882af5f0 x28: ffff8000882af650 x27: ffff8000882af768 x26: 0000000000000cc0 x25: 000000000000000d x24: ffff00010625b858 x23: ffff8000882af650 x22: ffffffdfc0900000 x21: 0000000000000000 x20: 0000000000000000 x19: ffffffdfc0900000 x18: 0000000000000000 x17: 0000000000000000 x16: 0000018000000000 x15: 52f8004000000000 x14: 0000e00000000000 x13: 0000000000002000 x12: 0000000000000020 x11: 52f8000000000000 x10: 52f8e1c0ffff6000 x9 : ffffbeb9619a681c x8 : 0000000000000003 x7 : 0000000000000000 x6 : ffff00010b02ddb0 x5 : ffffbeb96395e378 x4 : 0000000000000000 x3 : 0000000000000cc0 x2 : 000000000000000d x1 : 000000000000000c x0 : 0000000000000000 Call trace: xas_split_alloc+0xf8/0x128 split_huge_page_to_list_to_order+0x1c4/0x720 truncate_inode_partial_folio+0xdc/0x160 shmem_undo_range+0x2bc/0x6a8 shmem_fallocate+0x134/0x430 vfs_fallocate+0x124/0x2e8 ksys_fallocate+0x4c/0xa0 __arm64_sys_fallocate+0x24/0x38 invoke_syscall.constprop.0+0x7c/0xd8 do_el0_svc+0xb4/0xd0 el0_svc+0x44/0x1d8 el0t_64_sync_handler+0x134/0x150 el0t_64_sync+0x17c/0x180 Fix it by disabling PMD-sized page cache when HPAGE_PMD_ORDER is larger than MAX_PAGECACHE_ORDER. As Matthew Wilcox pointed, the page cache in a shmem file isn't represented by a multi-index entry and doesn't have this limitation when the xarry entry is split until commit 6b24ca4a1a8d ("mm: Use multi-index entries in the page cache"). Link: https://lkml.kernel.org/r/20240627003953.1262512-5-gshan@redhat.com Fixes: 6b24ca4a1a8d ("mm: Use multi-index entries in the page cache") Signed-off-by: Gavin Shan <gshan(a)redhat.com> Acked-by: David Hildenbrand <david(a)redhat.com> Cc: Darrick J. Wong <djwong(a)kernel.org> Cc: Don Dutile <ddutile(a)redhat.com> Cc: Hugh Dickins <hughd(a)google.com> Cc: Linus Torvalds <torvalds(a)linux-foundation.org> Cc: Matthew Wilcox (Oracle) <willy(a)infradead.org> Cc: Ryan Roberts <ryan.roberts(a)arm.com> Cc: William Kucharski <william.kucharski(a)oracle.com> Cc: Zhenyu Zhang <zhenyzha(a)redhat.com> Cc: <stable(a)vger.kernel.org> [5.17+] Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/shmem.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) --- a/mm/shmem.c~mm-shmem-disable-pmd-sized-page-cache-if-needed +++ a/mm/shmem.c @@ -541,8 +541,9 @@ static bool shmem_confirm_swap(struct ad static int shmem_huge __read_mostly = SHMEM_HUGE_NEVER; -bool shmem_is_huge(struct inode *inode, pgoff_t index, bool shmem_huge_force, - struct mm_struct *mm, unsigned long vm_flags) +static bool __shmem_is_huge(struct inode *inode, pgoff_t index, + bool shmem_huge_force, struct mm_struct *mm, + unsigned long vm_flags) { loff_t i_size; @@ -573,6 +574,16 @@ bool shmem_is_huge(struct inode *inode, } } +bool shmem_is_huge(struct inode *inode, pgoff_t index, + bool shmem_huge_force, struct mm_struct *mm, + unsigned long vm_flags) +{ + if (HPAGE_PMD_ORDER > MAX_PAGECACHE_ORDER) + return false; + + return __shmem_is_huge(inode, index, shmem_huge_force, mm, vm_flags); +} + #if defined(CONFIG_SYSFS) static int shmem_parse_huge(const char *str) { _ Patches currently in -mm which might be from gshan(a)redhat.com are

5 months, 3 weeks

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[merged mm-hotfixes-stable] mm-filemap-skip-to-create-pmd-sized-page-cache-if-needed.patch removed from -mm tree

by Andrew Morton

The quilt patch titled Subject: mm/filemap: skip to create PMD-sized page cache if needed has been removed from the -mm tree. Its filename was mm-filemap-skip-to-create-pmd-sized-page-cache-if-needed.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: Gavin Shan <gshan(a)redhat.com> Subject: mm/filemap: skip to create PMD-sized page cache if needed Date: Thu, 27 Jun 2024 10:39:51 +1000 On ARM64, HPAGE_PMD_ORDER is 13 when the base page size is 64KB. The PMD-sized page cache can't be supported by xarray as the following error messages indicate. ------------[ cut here ]------------ WARNING: CPU: 35 PID: 7484 at lib/xarray.c:1025 xas_split_alloc+0xf8/0x128 Modules linked in: nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib \ nft_reject_inet nf_reject_ipv4 nf_reject_ipv6 nft_reject nft_ct \ nft_chain_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 \ ip_set rfkill nf_tables nfnetlink vfat fat virtio_balloon drm \ fuse xfs libcrc32c crct10dif_ce ghash_ce sha2_ce sha256_arm64 \ sha1_ce virtio_net net_failover virtio_console virtio_blk failover \ dimlib virtio_mmio CPU: 35 PID: 7484 Comm: test Kdump: loaded Tainted: G W 6.10.0-rc5-gavin+ #9 Hardware name: QEMU KVM Virtual Machine, BIOS edk2-20240524-1.el9 05/24/2024 pstate: 83400005 (Nzcv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--) pc : xas_split_alloc+0xf8/0x128 lr : split_huge_page_to_list_to_order+0x1c4/0x720 sp : ffff800087a4f6c0 x29: ffff800087a4f6c0 x28: ffff800087a4f720 x27: 000000001fffffff x26: 0000000000000c40 x25: 000000000000000d x24: ffff00010625b858 x23: ffff800087a4f720 x22: ffffffdfc0780000 x21: 0000000000000000 x20: 0000000000000000 x19: ffffffdfc0780000 x18: 000000001ff40000 x17: 00000000ffffffff x16: 0000018000000000 x15: 51ec004000000000 x14: 0000e00000000000 x13: 0000000000002000 x12: 0000000000000020 x11: 51ec000000000000 x10: 51ece1c0ffff8000 x9 : ffffbeb961a44d28 x8 : 0000000000000003 x7 : ffffffdfc0456420 x6 : ffff0000e1aa6eb8 x5 : 20bf08b4fe778fca x4 : ffffffdfc0456420 x3 : 0000000000000c40 x2 : 000000000000000d x1 : 000000000000000c x0 : 0000000000000000 Call trace: xas_split_alloc+0xf8/0x128 split_huge_page_to_list_to_order+0x1c4/0x720 truncate_inode_partial_folio+0xdc/0x160 truncate_inode_pages_range+0x1b4/0x4a8 truncate_pagecache_range+0x84/0xa0 xfs_flush_unmap_range+0x70/0x90 [xfs] xfs_file_fallocate+0xfc/0x4d8 [xfs] vfs_fallocate+0x124/0x2e8 ksys_fallocate+0x4c/0xa0 __arm64_sys_fallocate+0x24/0x38 invoke_syscall.constprop.0+0x7c/0xd8 do_el0_svc+0xb4/0xd0 el0_svc+0x44/0x1d8 el0t_64_sync_handler+0x134/0x150 el0t_64_sync+0x17c/0x180 Fix it by skipping to allocate PMD-sized page cache when its size is larger than MAX_PAGECACHE_ORDER. For this specific case, we will fall to regular path where the readahead window is determined by BDI's sysfs file (read_ahead_kb). Link: https://lkml.kernel.org/r/20240627003953.1262512-4-gshan@redhat.com Fixes: 4687fdbb805a ("mm/filemap: Support VM_HUGEPAGE for file mappings") Signed-off-by: Gavin Shan <gshan(a)redhat.com> Suggested-by: David Hildenbrand <david(a)redhat.com> Acked-by: David Hildenbrand <david(a)redhat.com> Cc: Darrick J. Wong <djwong(a)kernel.org> Cc: Don Dutile <ddutile(a)redhat.com> Cc: Hugh Dickins <hughd(a)google.com> Cc: Linus Torvalds <torvalds(a)linux-foundation.org> Cc: Matthew Wilcox (Oracle) <willy(a)infradead.org> Cc: Ryan Roberts <ryan.roberts(a)arm.com> Cc: William Kucharski <william.kucharski(a)oracle.com> Cc: Zhenyu Zhang <zhenyzha(a)redhat.com> Cc: <stable(a)vger.kernel.org> [5.18+] Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/filemap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/mm/filemap.c~mm-filemap-skip-to-create-pmd-sized-page-cache-if-needed +++ a/mm/filemap.c @@ -3124,7 +3124,7 @@ static struct file *do_sync_mmap_readahe #ifdef CONFIG_TRANSPARENT_HUGEPAGE /* Use the readahead code, even if readahead is disabled */ - if (vm_flags & VM_HUGEPAGE) { + if ((vm_flags & VM_HUGEPAGE) && HPAGE_PMD_ORDER <= MAX_PAGECACHE_ORDER) { fpin = maybe_unlock_mmap_for_io(vmf, fpin); ractl._index &= ~((unsigned long)HPAGE_PMD_NR - 1); ra->size = HPAGE_PMD_NR; _ Patches currently in -mm which might be from gshan(a)redhat.com are

5 months, 3 weeks

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[merged mm-hotfixes-stable] mm-readahead-limit-page-cache-size-in-page_cache_ra_order.patch removed from -mm tree

by Andrew Morton

The quilt patch titled Subject: mm/readahead: limit page cache size in page_cache_ra_order() has been removed from the -mm tree. Its filename was mm-readahead-limit-page-cache-size-in-page_cache_ra_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: Gavin Shan <gshan(a)redhat.com> Subject: mm/readahead: limit page cache size in page_cache_ra_order() Date: Thu, 27 Jun 2024 10:39:50 +1000 In page_cache_ra_order(), the maximal order of the page cache to be allocated shouldn't be larger than MAX_PAGECACHE_ORDER. Otherwise, it's possible the large page cache can't be supported by xarray when the corresponding xarray entry is split. For example, HPAGE_PMD_ORDER is 13 on ARM64 when the base page size is 64KB. The PMD-sized page cache can't be supported by xarray. Link: https://lkml.kernel.org/r/20240627003953.1262512-3-gshan@redhat.com Fixes: 793917d997df ("mm/readahead: Add large folio readahead") Signed-off-by: Gavin Shan <gshan(a)redhat.com> Acked-by: David Hildenbrand <david(a)redhat.com> Cc: Darrick J. Wong <djwong(a)kernel.org> Cc: Don Dutile <ddutile(a)redhat.com> Cc: Hugh Dickins <hughd(a)google.com> Cc: Linus Torvalds <torvalds(a)linux-foundation.org> Cc: Matthew Wilcox (Oracle) <willy(a)infradead.org> Cc: Ryan Roberts <ryan.roberts(a)arm.com> Cc: William Kucharski <william.kucharski(a)oracle.com> Cc: Zhenyu Zhang <zhenyzha(a)redhat.com> Cc: <stable(a)vger.kernel.org> [5.18+] Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/readahead.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) --- a/mm/readahead.c~mm-readahead-limit-page-cache-size-in-page_cache_ra_order +++ a/mm/readahead.c @@ -503,11 +503,11 @@ void page_cache_ra_order(struct readahea limit = min(limit, index + ra->size - 1); - if (new_order < MAX_PAGECACHE_ORDER) { + if (new_order < MAX_PAGECACHE_ORDER) new_order += 2; - new_order = min_t(unsigned int, MAX_PAGECACHE_ORDER, new_order); - new_order = min_t(unsigned int, new_order, ilog2(ra->size)); - } + + new_order = min_t(unsigned int, MAX_PAGECACHE_ORDER, new_order); + new_order = min_t(unsigned int, new_order, ilog2(ra->size)); /* See comment in page_cache_ra_unbounded() */ nofs = memalloc_nofs_save(); _ Patches currently in -mm which might be from gshan(a)redhat.com are

5 months, 3 weeks

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[merged mm-hotfixes-stable] mm-filemap-make-max_pagecache_order-acceptable-to-xarray.patch removed from -mm tree

by Andrew Morton

The quilt patch titled Subject: mm/filemap: make MAX_PAGECACHE_ORDER acceptable to xarray has been removed from the -mm tree. Its filename was mm-filemap-make-max_pagecache_order-acceptable-to-xarray.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: Gavin Shan <gshan(a)redhat.com> Subject: mm/filemap: make MAX_PAGECACHE_ORDER acceptable to xarray Date: Thu, 27 Jun 2024 10:39:49 +1000 Patch series "mm/filemap: Limit page cache size to that supported by xarray", v2. Currently, xarray can't support arbitrary page cache size. More details can be found from the WARN_ON() statement in xas_split_alloc(). In our test whose code is attached below, we hit the WARN_ON() on ARM64 system where the base page size is 64KB and huge page size is 512MB. The issue was reported long time ago and some discussions on it can be found here [1]. [1] https://www.spinics.net/lists/linux-xfs/msg75404.html In order to fix the issue, we need to adjust MAX_PAGECACHE_ORDER to one supported by xarray and avoid PMD-sized page cache if needed. The code changes are suggested by David Hildenbrand. PATCH[1] adjusts MAX_PAGECACHE_ORDER to that supported by xarray PATCH[2-3] avoids PMD-sized page cache in the synchronous readahead path PATCH[4] avoids PMD-sized page cache for shmem files if needed Test program ============ # cat test.c #define _GNU_SOURCE #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <string.h> #include <fcntl.h> #include <errno.h> #include <sys/syscall.h> #include <sys/mman.h> #define TEST_XFS_FILENAME "/tmp/data" #define TEST_SHMEM_FILENAME "/dev/shm/data" #define TEST_MEM_SIZE 0x20000000 int main(int argc, char **argv) { const char *filename; int fd = 0; void *buf = (void *)-1, *p; int pgsize = getpagesize(); int ret; if (pgsize != 0x10000) { fprintf(stderr, "64KB base page size is required\n"); return -EPERM; } system("echo force > /sys/kernel/mm/transparent_hugepage/shmem_enabled"); system("rm -fr /tmp/data"); system("rm -fr /dev/shm/data"); system("echo 1 > /proc/sys/vm/drop_caches"); /* Open xfs or shmem file */ filename = TEST_XFS_FILENAME; if (argc > 1 && !strcmp(argv[1], "shmem")) filename = TEST_SHMEM_FILENAME; fd = open(filename, O_CREAT | O_RDWR | O_TRUNC); if (fd < 0) { fprintf(stderr, "Unable to open <%s>\n", filename); return -EIO; } /* Extend file size */ ret = ftruncate(fd, TEST_MEM_SIZE); if (ret) { fprintf(stderr, "Error %d to ftruncate()\n", ret); goto cleanup; } /* Create VMA */ buf = mmap(NULL, TEST_MEM_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); if (buf == (void *)-1) { fprintf(stderr, "Unable to mmap <%s>\n", filename); goto cleanup; } fprintf(stdout, "mapped buffer at 0x%p\n", buf); ret = madvise(buf, TEST_MEM_SIZE, MADV_HUGEPAGE); if (ret) { fprintf(stderr, "Unable to madvise(MADV_HUGEPAGE)\n"); goto cleanup; } /* Populate VMA */ ret = madvise(buf, TEST_MEM_SIZE, MADV_POPULATE_WRITE); if (ret) { fprintf(stderr, "Error %d to madvise(MADV_POPULATE_WRITE)\n", ret); goto cleanup; } /* Punch the file to enforce xarray split */ ret = fallocate(fd, FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE, TEST_MEM_SIZE - pgsize, pgsize); if (ret) fprintf(stderr, "Error %d to fallocate()\n", ret); cleanup: if (buf != (void *)-1) munmap(buf, TEST_MEM_SIZE); if (fd > 0) close(fd); return 0; } # gcc test.c -o test # cat /proc/1/smaps | grep KernelPageSize | head -n 1 KernelPageSize: 64 kB # ./test shmem : ------------[ cut here ]------------ WARNING: CPU: 17 PID: 5253 at lib/xarray.c:1025 xas_split_alloc+0xf8/0x128 Modules linked in: nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib \ nft_reject_inet nf_reject_ipv4 nf_reject_ipv6 nft_reject nft_ct \ nft_chain_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 \ ip_set nf_tables rfkill nfnetlink vfat fat virtio_balloon \ drm fuse xfs libcrc32c crct10dif_ce ghash_ce sha2_ce sha256_arm64 \ virtio_net sha1_ce net_failover failover virtio_console virtio_blk \ dimlib virtio_mmio CPU: 17 PID: 5253 Comm: test Kdump: loaded Tainted: G W 6.10.0-rc5-gavin+ #12 Hardware name: QEMU KVM Virtual Machine, BIOS edk2-20240524-1.el9 05/24/2024 pstate: 83400005 (Nzcv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--) pc : xas_split_alloc+0xf8/0x128 lr : split_huge_page_to_list_to_order+0x1c4/0x720 sp : ffff80008a92f5b0 x29: ffff80008a92f5b0 x28: ffff80008a92f610 x27: ffff80008a92f728 x26: 0000000000000cc0 x25: 000000000000000d x24: ffff0000cf00c858 x23: ffff80008a92f610 x22: ffffffdfc0600000 x21: 0000000000000000 x20: 0000000000000000 x19: ffffffdfc0600000 x18: 0000000000000000 x17: 0000000000000000 x16: 0000018000000000 x15: 3374004000000000 x14: 0000e00000000000 x13: 0000000000002000 x12: 0000000000000020 x11: 3374000000000000 x10: 3374e1c0ffff6000 x9 : ffffb463a84c681c x8 : 0000000000000003 x7 : 0000000000000000 x6 : ffff00011c976ce0 x5 : ffffb463aa47e378 x4 : 0000000000000000 x3 : 0000000000000cc0 x2 : 000000000000000d x1 : 000000000000000c x0 : 0000000000000000 Call trace: xas_split_alloc+0xf8/0x128 split_huge_page_to_list_to_order+0x1c4/0x720 truncate_inode_partial_folio+0xdc/0x160 shmem_undo_range+0x2bc/0x6a8 shmem_fallocate+0x134/0x430 vfs_fallocate+0x124/0x2e8 ksys_fallocate+0x4c/0xa0 __arm64_sys_fallocate+0x24/0x38 invoke_syscall.constprop.0+0x7c/0xd8 do_el0_svc+0xb4/0xd0 el0_svc+0x44/0x1d8 el0t_64_sync_handler+0x134/0x150 el0t_64_sync+0x17c/0x180 This patch (of 4): The largest page cache order can be HPAGE_PMD_ORDER (13) on ARM64 with 64KB base page size. The xarray entry with this order can't be split as the following error messages indicate. ------------[ cut here ]------------ WARNING: CPU: 35 PID: 7484 at lib/xarray.c:1025 xas_split_alloc+0xf8/0x128 Modules linked in: nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib \ nft_reject_inet nf_reject_ipv4 nf_reject_ipv6 nft_reject nft_ct \ nft_chain_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 \ ip_set rfkill nf_tables nfnetlink vfat fat virtio_balloon drm \ fuse xfs libcrc32c crct10dif_ce ghash_ce sha2_ce sha256_arm64 \ sha1_ce virtio_net net_failover virtio_console virtio_blk failover \ dimlib virtio_mmio CPU: 35 PID: 7484 Comm: test Kdump: loaded Tainted: G W 6.10.0-rc5-gavin+ #9 Hardware name: QEMU KVM Virtual Machine, BIOS edk2-20240524-1.el9 05/24/2024 pstate: 83400005 (Nzcv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--) pc : xas_split_alloc+0xf8/0x128 lr : split_huge_page_to_list_to_order+0x1c4/0x720 sp : ffff800087a4f6c0 x29: ffff800087a4f6c0 x28: ffff800087a4f720 x27: 000000001fffffff x26: 0000000000000c40 x25: 000000000000000d x24: ffff00010625b858 x23: ffff800087a4f720 x22: ffffffdfc0780000 x21: 0000000000000000 x20: 0000000000000000 x19: ffffffdfc0780000 x18: 000000001ff40000 x17: 00000000ffffffff x16: 0000018000000000 x15: 51ec004000000000 x14: 0000e00000000000 x13: 0000000000002000 x12: 0000000000000020 x11: 51ec000000000000 x10: 51ece1c0ffff8000 x9 : ffffbeb961a44d28 x8 : 0000000000000003 x7 : ffffffdfc0456420 x6 : ffff0000e1aa6eb8 x5 : 20bf08b4fe778fca x4 : ffffffdfc0456420 x3 : 0000000000000c40 x2 : 000000000000000d x1 : 000000000000000c x0 : 0000000000000000 Call trace: xas_split_alloc+0xf8/0x128 split_huge_page_to_list_to_order+0x1c4/0x720 truncate_inode_partial_folio+0xdc/0x160 truncate_inode_pages_range+0x1b4/0x4a8 truncate_pagecache_range+0x84/0xa0 xfs_flush_unmap_range+0x70/0x90 [xfs] xfs_file_fallocate+0xfc/0x4d8 [xfs] vfs_fallocate+0x124/0x2e8 ksys_fallocate+0x4c/0xa0 __arm64_sys_fallocate+0x24/0x38 invoke_syscall.constprop.0+0x7c/0xd8 do_el0_svc+0xb4/0xd0 el0_svc+0x44/0x1d8 el0t_64_sync_handler+0x134/0x150 el0t_64_sync+0x17c/0x180 Fix it by decreasing MAX_PAGECACHE_ORDER to the largest supported order by xarray. For this specific case, MAX_PAGECACHE_ORDER is dropped from 13 to 11 when CONFIG_BASE_SMALL is disabled. Link: https://lkml.kernel.org/r/20240627003953.1262512-1-gshan@redhat.com Link: https://lkml.kernel.org/r/20240627003953.1262512-2-gshan@redhat.com Fixes: 793917d997df ("mm/readahead: Add large folio readahead") Signed-off-by: Gavin Shan <gshan(a)redhat.com> Suggested-by: David Hildenbrand <david(a)redhat.com> Acked-by: David Hildenbrand <david(a)redhat.com> Cc: Darrick J. Wong <djwong(a)kernel.org> Cc: Don Dutile <ddutile(a)redhat.com> Cc: Hugh Dickins <hughd(a)google.com> Cc: Linus Torvalds <torvalds(a)linux-foundation.org> Cc: Matthew Wilcox (Oracle) <willy(a)infradead.org> Cc: Ryan Roberts <ryan.roberts(a)arm.com> Cc: William Kucharski <william.kucharski(a)oracle.com> Cc: Zhenyu Zhang <zhenyzha(a)redhat.com> Cc: <stable(a)vger.kernel.org> [5.18+] Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- include/linux/pagemap.h | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) --- a/include/linux/pagemap.h~mm-filemap-make-max_pagecache_order-acceptable-to-xarray +++ a/include/linux/pagemap.h @@ -354,11 +354,18 @@ static inline void mapping_set_gfp_mask( * a good order (that's 1MB if you're using 4kB pages) */ #ifdef CONFIG_TRANSPARENT_HUGEPAGE -#define MAX_PAGECACHE_ORDER HPAGE_PMD_ORDER +#define PREFERRED_MAX_PAGECACHE_ORDER HPAGE_PMD_ORDER #else -#define MAX_PAGECACHE_ORDER 8 +#define PREFERRED_MAX_PAGECACHE_ORDER 8 #endif +/* + * xas_split_alloc() does not support arbitrary orders. This implies no + * 512MB THP on ARM64 with 64KB base page size. + */ +#define MAX_XAS_ORDER (XA_CHUNK_SHIFT * 2 - 1) +#define MAX_PAGECACHE_ORDER min(MAX_XAS_ORDER, PREFERRED_MAX_PAGECACHE_ORDER) + /** * mapping_set_large_folios() - Indicate the file supports large folios. * @mapping: The file. _ Patches currently in -mm which might be from gshan(a)redhat.com are

5 months, 3 weeks

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[merged mm-hotfixes-stable] mm-damon-core-merge-regions-aggressively-when-max_nr_regions-is-unmet.patch removed from -mm tree

by Andrew Morton

The quilt patch titled Subject: mm/damon/core: merge regions aggressively when max_nr_regions is unmet has been removed from the -mm tree. Its filename was mm-damon-core-merge-regions-aggressively-when-max_nr_regions-is-unmet.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: SeongJae Park <sj(a)kernel.org> Subject: mm/damon/core: merge regions aggressively when max_nr_regions is unmet Date: Mon, 24 Jun 2024 10:58:14 -0700 DAMON keeps the number of regions under max_nr_regions by skipping regions split operations when doing so can make the number higher than the limit. It works well for preventing violation of the limit. But, if somehow the violation happens, it cannot recovery well depending on the situation. In detail, if the real number of regions having different access pattern is higher than the limit, the mechanism cannot reduce the number below the limit. In such a case, the system could suffer from high monitoring overhead of DAMON. The violation can actually happen. For an example, the user could reduce max_nr_regions while DAMON is running, to be lower than the current number of regions. Fix the problem by repeating the merge operations with increasing aggressiveness in kdamond_merge_regions() for the case, until the limit is met. [sj(a)kernel.org: increase regions merge aggressiveness while respecting min_nr_regions] Link: https://lkml.kernel.org/r/20240626164753.46270-1-sj@kernel.org [sj(a)kernel.org: ensure max threshold attempt for max_nr_regions violation] Link: https://lkml.kernel.org/r/20240627163153.75969-1-sj@kernel.org Link: https://lkml.kernel.org/r/20240624175814.89611-1-sj@kernel.org Fixes: b9a6ac4e4ede ("mm/damon: adaptively adjust regions") Signed-off-by: SeongJae Park <sj(a)kernel.org> Cc: <stable(a)vger.kernel.org> [5.15+] Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/damon/core.c | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-) --- a/mm/damon/core.c~mm-damon-core-merge-regions-aggressively-when-max_nr_regions-is-unmet +++ a/mm/damon/core.c @@ -1358,14 +1358,31 @@ static void damon_merge_regions_of(struc * access frequencies are similar. This is for minimizing the monitoring * overhead under the dynamically changeable access pattern. If a merge was * unnecessarily made, later 'kdamond_split_regions()' will revert it. + * + * The total number of regions could be higher than the user-defined limit, + * max_nr_regions for some cases. For example, the user can update + * max_nr_regions to a number that lower than the current number of regions + * while DAMON is running. For such a case, repeat merging until the limit is + * met while increasing @threshold up to possible maximum level. */ static void kdamond_merge_regions(struct damon_ctx *c, unsigned int threshold, unsigned long sz_limit) { struct damon_target *t; + unsigned int nr_regions; + unsigned int max_thres; - damon_for_each_target(t, c) - damon_merge_regions_of(t, threshold, sz_limit); + max_thres = c->attrs.aggr_interval / + (c->attrs.sample_interval ? c->attrs.sample_interval : 1); + do { + nr_regions = 0; + damon_for_each_target(t, c) { + damon_merge_regions_of(t, threshold, sz_limit); + nr_regions += damon_nr_regions(t); + } + threshold = max(1, threshold * 2); + } while (nr_regions > c->attrs.max_nr_regions && + threshold / 2 < max_thres); } /* _ Patches currently in -mm which might be from sj(a)kernel.org are mm-damon-paddr-initialize-nr_succeeded-in-__damon_pa_migrate_folio_list.patch docs-mm-damon-design-fix-two-typos.patch docs-mm-damon-design-clarify-regions-merging-operation.patch docs-admin-guide-mm-damon-start-add-access-pattern-snapshot-example.patch docs-mm-damon-design-add-links-from-overall-architecture-to-sections-of-details.patch docs-mm-damon-design-move-configurable-operations-set-section-into-operations-set-layer-section.patch docs-mm-damon-design-remove-programmable-modules-section-in-favor-of-modules-section.patch docs-mm-damon-design-add-links-to-sections-of-damon-sysfs-interface-usage-doc.patch docs-mm-damon-index-add-links-to-design.patch docs-mm-damon-index-add-links-to-admin-guide-doc.patch

5 months, 3 weeks

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[merged mm-hotfixes-stable] fix-userfaultfd_api-to-return-einval-as-expected.patch removed from -mm tree

by Andrew Morton

The quilt patch titled Subject: Fix userfaultfd_api to return EINVAL as expected has been removed from the -mm tree. Its filename was fix-userfaultfd_api-to-return-einval-as-expected.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: Audra Mitchell <audra(a)redhat.com> Subject: Fix userfaultfd_api to return EINVAL as expected Date: Wed, 26 Jun 2024 09:05:11 -0400 Currently if we request a feature that is not set in the Kernel config we fail silently and return all the available features. However, the man page indicates we should return an EINVAL. We need to fix this issue since we can end up with a Kernel warning should a program request the feature UFFD_FEATURE_WP_UNPOPULATED on a kernel with the config not set with this feature. [ 200.812896] WARNING: CPU: 91 PID: 13634 at mm/memory.c:1660 zap_pte_range+0x43d/0x660 [ 200.820738] Modules linked in: [ 200.869387] CPU: 91 PID: 13634 Comm: userfaultfd Kdump: loaded Not tainted 6.9.0-rc5+ #8 [ 200.877477] Hardware name: Dell Inc. PowerEdge R6525/0N7YGH, BIOS 2.7.3 03/30/2022 [ 200.885052] RIP: 0010:zap_pte_range+0x43d/0x660 Link: https://lkml.kernel.org/r/20240626130513.120193-1-audra@redhat.com Fixes: e06f1e1dd499 ("userfaultfd: wp: enabled write protection in userfaultfd API") Signed-off-by: Audra Mitchell <audra(a)redhat.com> Cc: Al Viro <viro(a)zeniv.linux.org.uk> Cc: Andrea Arcangeli <aarcange(a)redhat.com> Cc: Christian Brauner <brauner(a)kernel.org> Cc: Jan Kara <jack(a)suse.cz> Cc: Mike Rapoport <rppt(a)linux.vnet.ibm.com> Cc: Peter Xu <peterx(a)redhat.com> Cc: Rafael Aquini <raquini(a)redhat.com> Cc: Shaohua Li <shli(a)fb.com> Cc: Shuah Khan <shuah(a)kernel.org> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- fs/userfaultfd.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) --- a/fs/userfaultfd.c~fix-userfaultfd_api-to-return-einval-as-expected +++ a/fs/userfaultfd.c @@ -2057,7 +2057,7 @@ static int userfaultfd_api(struct userfa goto out; features = uffdio_api.features; ret = -EINVAL; - if (uffdio_api.api != UFFD_API || (features & ~UFFD_API_FEATURES)) + if (uffdio_api.api != UFFD_API) goto err_out; ret = -EPERM; if ((features & UFFD_FEATURE_EVENT_FORK) && !capable(CAP_SYS_PTRACE)) @@ -2081,6 +2081,11 @@ static int userfaultfd_api(struct userfa uffdio_api.features &= ~UFFD_FEATURE_WP_UNPOPULATED; uffdio_api.features &= ~UFFD_FEATURE_WP_ASYNC; #endif + + ret = -EINVAL; + if (features & ~uffdio_api.features) + goto err_out; + uffdio_api.ioctls = UFFD_API_IOCTLS; ret = -EFAULT; if (copy_to_user(buf, &uffdio_api, sizeof(uffdio_api))) _ Patches currently in -mm which might be from audra(a)redhat.com are update-uffd-stress-to-handle-einval-for-unset-config-features.patch turn-off-test_uffdio_wp-if-config_pte_marker_uffd_wp-is-not-configured.patch

5 months, 3 weeks

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[merged mm-hotfixes-stable] mm-vmalloc-check-if-a-hash-index-is-in-cpu_possible_mask.patch removed from -mm tree

by Andrew Morton

The quilt patch titled Subject: mm: vmalloc: check if a hash-index is in cpu_possible_mask has been removed from the -mm tree. Its filename was mm-vmalloc-check-if-a-hash-index-is-in-cpu_possible_mask.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: "Uladzislau Rezki (Sony)" <urezki(a)gmail.com> Subject: mm: vmalloc: check if a hash-index is in cpu_possible_mask Date: Wed, 26 Jun 2024 16:03:30 +0200 The problem is that there are systems where cpu_possible_mask has gaps between set CPUs, for example SPARC. In this scenario addr_to_vb_xa() hash function can return an index which accesses to not-possible and not setup CPU area using per_cpu() macro. This results in an oops on SPARC. A per-cpu vmap_block_queue is also used as hash table, incorrectly assuming the cpu_possible_mask has no gaps. Fix it by adjusting an index to a next possible CPU. Link: https://lkml.kernel.org/r/20240626140330.89836-1-urezki@gmail.com Fixes: 062eacf57ad9 ("mm: vmalloc: remove a global vmap_blocks xarray") Reported-by: Nick Bowler <nbowler(a)draconx.ca> Closes: https://lore.kernel.org/linux-kernel/ZntjIE6msJbF8zTa@MiWiFi-R3L-srv/T/ Signed-off-by: Uladzislau Rezki (Sony) <urezki(a)gmail.com> Reviewed-by: Baoquan He <bhe(a)redhat.com> Cc: Christoph Hellwig <hch(a)infradead.org> Cc: Hailong.Liu <hailong.liu(a)oppo.com> Cc: Oleksiy Avramchenko <oleksiy.avramchenko(a)sony.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/vmalloc.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) --- a/mm/vmalloc.c~mm-vmalloc-check-if-a-hash-index-is-in-cpu_possible_mask +++ a/mm/vmalloc.c @@ -2543,7 +2543,15 @@ static DEFINE_PER_CPU(struct vmap_block_ static struct xarray * addr_to_vb_xa(unsigned long addr) { - int index = (addr / VMAP_BLOCK_SIZE) % num_possible_cpus(); + int index = (addr / VMAP_BLOCK_SIZE) % nr_cpu_ids; + + /* + * Please note, nr_cpu_ids points on a highest set + * possible bit, i.e. we never invoke cpumask_next() + * if an index points on it which is nr_cpu_ids - 1. + */ + if (!cpu_possible(index)) + index = cpumask_next(index, cpu_possible_mask); return &per_cpu(vmap_block_queue, index).vmap_blocks; } _ Patches currently in -mm which might be from urezki(a)gmail.com are

5 months, 3 weeks

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[merged mm-hotfixes-stable] mm-page_ref-remove-folio_try_get_rcu.patch removed from -mm tree

by Andrew Morton

The quilt patch titled Subject: mm: page_ref: remove folio_try_get_rcu() has been removed from the -mm tree. Its filename was mm-page_ref-remove-folio_try_get_rcu.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: Yang Shi <yang(a)os.amperecomputing.com> Subject: mm: page_ref: remove folio_try_get_rcu() Date: Tue, 25 Jun 2024 13:53:50 -0700 The below bug was reported on a non-SMP kernel: [ 275.267158][ T4335] ------------[ cut here ]------------ [ 275.267949][ T4335] kernel BUG at include/linux/page_ref.h:275! [ 275.268526][ T4335] invalid opcode: 0000 [#1] KASAN PTI [ 275.269001][ T4335] CPU: 0 PID: 4335 Comm: trinity-c3 Not tainted 6.7.0-rc4-00061-gefa7df3e3bb5 #1 [ 275.269787][ T4335] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 [ 275.270679][ T4335] RIP: 0010:try_get_folio (include/linux/page_ref.h:275 (discriminator 3) mm/gup.c:79 (discriminator 3)) [ 275.272813][ T4335] RSP: 0018:ffffc90005dcf650 EFLAGS: 00010202 [ 275.273346][ T4335] RAX: 0000000000000246 RBX: ffffea00066e0000 RCX: 0000000000000000 [ 275.274032][ T4335] RDX: fffff94000cdc007 RSI: 0000000000000004 RDI: ffffea00066e0034 [ 275.274719][ T4335] RBP: ffffea00066e0000 R08: 0000000000000000 R09: fffff94000cdc006 [ 275.275404][ T4335] R10: ffffea00066e0037 R11: 0000000000000000 R12: 0000000000000136 [ 275.276106][ T4335] R13: ffffea00066e0034 R14: dffffc0000000000 R15: ffffea00066e0008 [ 275.276790][ T4335] FS: 00007fa2f9b61740(0000) GS:ffffffff89d0d000(0000) knlGS:0000000000000000 [ 275.277570][ T4335] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 275.278143][ T4335] CR2: 00007fa2f6c00000 CR3: 0000000134b04000 CR4: 00000000000406f0 [ 275.278833][ T4335] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 275.279521][ T4335] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 275.280201][ T4335] Call Trace: [ 275.280499][ T4335] <TASK> [ 275.280751][ T4335] ? die (arch/x86/kernel/dumpstack.c:421 arch/x86/kernel/dumpstack.c:434 arch/x86/kernel/dumpstack.c:447) [ 275.281087][ T4335] ? do_trap (arch/x86/kernel/traps.c:112 arch/x86/kernel/traps.c:153) [ 275.281463][ T4335] ? try_get_folio (include/linux/page_ref.h:275 (discriminator 3) mm/gup.c:79 (discriminator 3)) [ 275.281884][ T4335] ? try_get_folio (include/linux/page_ref.h:275 (discriminator 3) mm/gup.c:79 (discriminator 3)) [ 275.282300][ T4335] ? do_error_trap (arch/x86/kernel/traps.c:174) [ 275.282711][ T4335] ? try_get_folio (include/linux/page_ref.h:275 (discriminator 3) mm/gup.c:79 (discriminator 3)) [ 275.283129][ T4335] ? handle_invalid_op (arch/x86/kernel/traps.c:212) [ 275.283561][ T4335] ? try_get_folio (include/linux/page_ref.h:275 (discriminator 3) mm/gup.c:79 (discriminator 3)) [ 275.283990][ T4335] ? exc_invalid_op (arch/x86/kernel/traps.c:264) [ 275.284415][ T4335] ? asm_exc_invalid_op (arch/x86/include/asm/idtentry.h:568) [ 275.284859][ T4335] ? try_get_folio (include/linux/page_ref.h:275 (discriminator 3) mm/gup.c:79 (discriminator 3)) [ 275.285278][ T4335] try_grab_folio (mm/gup.c:148) [ 275.285684][ T4335] __get_user_pages (mm/gup.c:1297 (discriminator 1)) [ 275.286111][ T4335] ? __pfx___get_user_pages (mm/gup.c:1188) [ 275.286579][ T4335] ? __pfx_validate_chain (kernel/locking/lockdep.c:3825) [ 275.287034][ T4335] ? mark_lock (kernel/locking/lockdep.c:4656 (discriminator 1)) [ 275.287416][ T4335] __gup_longterm_locked (mm/gup.c:1509 mm/gup.c:2209) [ 275.288192][ T4335] ? __pfx___gup_longterm_locked (mm/gup.c:2204) [ 275.288697][ T4335] ? __pfx_lock_acquire (kernel/locking/lockdep.c:5722) [ 275.289135][ T4335] ? __pfx___might_resched (kernel/sched/core.c:10106) [ 275.289595][ T4335] pin_user_pages_remote (mm/gup.c:3350) [ 275.290041][ T4335] ? __pfx_pin_user_pages_remote (mm/gup.c:3350) [ 275.290545][ T4335] ? find_held_lock (kernel/locking/lockdep.c:5244 (discriminator 1)) [ 275.290961][ T4335] ? mm_access (kernel/fork.c:1573) [ 275.291353][ T4335] process_vm_rw_single_vec+0x142/0x360 [ 275.291900][ T4335] ? __pfx_process_vm_rw_single_vec+0x10/0x10 [ 275.292471][ T4335] ? mm_access (kernel/fork.c:1573) [ 275.292859][ T4335] process_vm_rw_core+0x272/0x4e0 [ 275.293384][ T4335] ? hlock_class (arch/x86/include/asm/bitops.h:227 arch/x86/include/asm/bitops.h:239 include/asm-generic/bitops/instrumented-non-atomic.h:142 kernel/locking/lockdep.c:228) [ 275.293780][ T4335] ? __pfx_process_vm_rw_core+0x10/0x10 [ 275.294350][ T4335] process_vm_rw (mm/process_vm_access.c:284) [ 275.294748][ T4335] ? __pfx_process_vm_rw (mm/process_vm_access.c:259) [ 275.295197][ T4335] ? __task_pid_nr_ns (include/linux/rcupdate.h:306 (discriminator 1) include/linux/rcupdate.h:780 (discriminator 1) kernel/pid.c:504 (discriminator 1)) [ 275.295634][ T4335] __x64_sys_process_vm_readv (mm/process_vm_access.c:291) [ 275.296139][ T4335] ? syscall_enter_from_user_mode (kernel/entry/common.c:94 kernel/entry/common.c:112) [ 275.296642][ T4335] do_syscall_64 (arch/x86/entry/common.c:51 (discriminator 1) arch/x86/entry/common.c:82 (discriminator 1)) [ 275.297032][ T4335] ? __task_pid_nr_ns (include/linux/rcupdate.h:306 (discriminator 1) include/linux/rcupdate.h:780 (discriminator 1) kernel/pid.c:504 (discriminator 1)) [ 275.297470][ T4335] ? lockdep_hardirqs_on_prepare (kernel/locking/lockdep.c:4300 kernel/locking/lockdep.c:4359) [ 275.297988][ T4335] ? do_syscall_64 (arch/x86/include/asm/cpufeature.h:171 arch/x86/entry/common.c:97) [ 275.298389][ T4335] ? lockdep_hardirqs_on_prepare (kernel/locking/lockdep.c:4300 kernel/locking/lockdep.c:4359) [ 275.298906][ T4335] ? do_syscall_64 (arch/x86/include/asm/cpufeature.h:171 arch/x86/entry/common.c:97) [ 275.299304][ T4335] ? do_syscall_64 (arch/x86/include/asm/cpufeature.h:171 arch/x86/entry/common.c:97) [ 275.299703][ T4335] ? do_syscall_64 (arch/x86/include/asm/cpufeature.h:171 arch/x86/entry/common.c:97) [ 275.300115][ T4335] entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:129) This BUG is the VM_BUG_ON(!in_atomic() && !irqs_disabled()) assertion in folio_ref_try_add_rcu() for non-SMP kernel. The process_vm_readv() calls GUP to pin the THP. An optimization for pinning THP instroduced by commit 57edfcfd3419 ("mm/gup: accelerate thp gup even for "pages != NULL"") calls try_grab_folio() to pin the THP, but try_grab_folio() is supposed to be called in atomic context for non-SMP kernel, for example, irq disabled or preemption disabled, due to the optimization introduced by commit e286781d5f2e ("mm: speculative page references"). The commit efa7df3e3bb5 ("mm: align larger anonymous mappings on THP boundaries") is not actually the root cause although it was bisected to. It just makes the problem exposed more likely. The follow up discussion suggested the optimization for non-SMP kernel may be out-dated and not worth it anymore [1]. So removing the optimization to silence the BUG. However calling try_grab_folio() in GUP slow path actually is unnecessary, so the following patch will clean this up. [1] https://lore.kernel.org/linux-mm/821cf1d6-92b9-4ac4-bacc-d8f2364ac14f@paulm… Link: https://lkml.kernel.org/r/20240625205350.1777481-1-yang@os.amperecomputing.… Fixes: 57edfcfd3419 ("mm/gup: accelerate thp gup even for "pages != NULL"") Signed-off-by: Yang Shi <yang(a)os.amperecomputing.com> Reported-by: kernel test robot <oliver.sang(a)intel.com> Tested-by: Oliver Sang <oliver.sang(a)intel.com> Acked-by: Peter Xu <peterx(a)redhat.com> Acked-by: David Hildenbrand <david(a)redhat.com> Cc: Christoph Lameter <cl(a)linux.com> Cc: Matthew Wilcox (Oracle) <willy(a)infradead.org> Cc: Paul E. McKenney <paulmck(a)kernel.org> Cc: Rik van Riel <riel(a)surriel.com> Cc: Vivek Kasireddy <vivek.kasireddy(a)intel.com> Cc: <stable(a)vger.kernel.org> [6.6+] Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- include/linux/page_ref.h | 49 +------------------------------------ mm/filemap.c | 10 +++---- mm/gup.c | 2 - 3 files changed, 8 insertions(+), 53 deletions(-) --- a/include/linux/page_ref.h~mm-page_ref-remove-folio_try_get_rcu +++ a/include/linux/page_ref.h @@ -258,54 +258,9 @@ static inline bool folio_try_get(struct return folio_ref_add_unless(folio, 1, 0); } -static inline bool folio_ref_try_add_rcu(struct folio *folio, int count) +static inline bool folio_ref_try_add(struct folio *folio, int count) { -#ifdef CONFIG_TINY_RCU - /* - * The caller guarantees the folio will not be freed from interrupt - * context, so (on !SMP) we only need preemption to be disabled - * and TINY_RCU does that for us. - */ -# ifdef CONFIG_PREEMPT_COUNT - VM_BUG_ON(!in_atomic() && !irqs_disabled()); -# endif - VM_BUG_ON_FOLIO(folio_ref_count(folio) == 0, folio); - folio_ref_add(folio, count); -#else - if (unlikely(!folio_ref_add_unless(folio, count, 0))) { - /* Either the folio has been freed, or will be freed. */ - return false; - } -#endif - return true; -} - -/** - * folio_try_get_rcu - Attempt to increase the refcount on a folio. - * @folio: The folio. - * - * This is a version of folio_try_get() optimised for non-SMP kernels. - * If you are still holding the rcu_read_lock() after looking up the - * page and know that the page cannot have its refcount decreased to - * zero in interrupt context, you can use this instead of folio_try_get(). - * - * Example users include get_user_pages_fast() (as pages are not unmapped - * from interrupt context) and the page cache lookups (as pages are not - * truncated from interrupt context). We also know that pages are not - * frozen in interrupt context for the purposes of splitting or migration. - * - * You can also use this function if you're holding a lock that prevents - * pages being frozen & removed; eg the i_pages lock for the page cache - * or the mmap_lock or page table lock for page tables. In this case, - * it will always succeed, and you could have used a plain folio_get(), - * but it's sometimes more convenient to have a common function called - * from both locked and RCU-protected contexts. - * - * Return: True if the reference count was successfully incremented. - */ -static inline bool folio_try_get_rcu(struct folio *folio) -{ - return folio_ref_try_add_rcu(folio, 1); + return folio_ref_add_unless(folio, count, 0); } static inline int page_ref_freeze(struct page *page, int count) --- a/mm/filemap.c~mm-page_ref-remove-folio_try_get_rcu +++ a/mm/filemap.c @@ -1847,7 +1847,7 @@ repeat: if (!folio || xa_is_value(folio)) goto out; - if (!folio_try_get_rcu(folio)) + if (!folio_try_get(folio)) goto repeat; if (unlikely(folio != xas_reload(&xas))) { @@ -2001,7 +2001,7 @@ retry: if (!folio || xa_is_value(folio)) return folio; - if (!folio_try_get_rcu(folio)) + if (!folio_try_get(folio)) goto reset; if (unlikely(folio != xas_reload(xas))) { @@ -2181,7 +2181,7 @@ unsigned filemap_get_folios_contig(struc if (xa_is_value(folio)) goto update_start; - if (!folio_try_get_rcu(folio)) + if (!folio_try_get(folio)) goto retry; if (unlikely(folio != xas_reload(&xas))) @@ -2313,7 +2313,7 @@ static void filemap_get_read_batch(struc break; if (xa_is_sibling(folio)) break; - if (!folio_try_get_rcu(folio)) + if (!folio_try_get(folio)) goto retry; if (unlikely(folio != xas_reload(&xas))) @@ -3472,7 +3472,7 @@ static struct folio *next_uptodate_folio continue; if (folio_test_locked(folio)) continue; - if (!folio_try_get_rcu(folio)) + if (!folio_try_get(folio)) continue; /* Has the page moved or been split? */ if (unlikely(folio != xas_reload(xas))) --- a/mm/gup.c~mm-page_ref-remove-folio_try_get_rcu +++ a/mm/gup.c @@ -76,7 +76,7 @@ retry: folio = page_folio(page); if (WARN_ON_ONCE(folio_ref_count(folio) < 0)) return NULL; - if (unlikely(!folio_ref_try_add_rcu(folio, refs))) + if (unlikely(!folio_ref_try_add(folio, refs))) return NULL; /* _ Patches currently in -mm which might be from yang(a)os.amperecomputing.com are mm-gup-stop-abusing-try_grab_folio.patch

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