From 84429b675bcfd2a518ae167ee4661cdf7539aa7d Mon Sep 17 00:00:00 2001 From: "Matthew Wilcox (Oracle)" Date: Thu, 22 Aug 2024 15:50:09 +0200 Subject: fs: Allow fine-grained control of folio sizes We need filesystems to be able to communicate acceptable folio sizes to the pagecache for a variety of uses (e.g. large block sizes). Support a range of folio sizes between order-0 and order-31. Signed-off-by: Matthew Wilcox (Oracle) Co-developed-by: Pankaj Raghav Signed-off-by: Pankaj Raghav Link: https://lore.kernel.org/r/20240822135018.1931258-2-kernel@pankajraghav.com Tested-by: David Howells Reviewed-by: Hannes Reinecke Reviewed-by: Darrick J. Wong Reviewed-by: Daniel Gomez Signed-off-by: Christian Brauner --- mm/filemap.c | 6 ++---- mm/readahead.c | 4 ++-- 2 files changed, 4 insertions(+), 6 deletions(-) (limited to 'mm') diff --git a/mm/filemap.c b/mm/filemap.c index d62150418b91..ad5e4a848070 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1933,10 +1933,8 @@ no_page: if (WARN_ON_ONCE(!(fgp_flags & (FGP_LOCK | FGP_FOR_MMAP)))) fgp_flags |= FGP_LOCK; - if (!mapping_large_folio_support(mapping)) - order = 0; - if (order > MAX_PAGECACHE_ORDER) - order = MAX_PAGECACHE_ORDER; + if (order > mapping_max_folio_order(mapping)) + order = mapping_max_folio_order(mapping); /* If we're not aligned, allocate a smaller folio */ if (index & ((1UL << order) - 1)) order = __ffs(index); diff --git a/mm/readahead.c b/mm/readahead.c index 517c0be7ce66..3e5239e9e177 100644 --- a/mm/readahead.c +++ b/mm/readahead.c @@ -449,10 +449,10 @@ void page_cache_ra_order(struct readahead_control *ractl, limit = min(limit, index + ra->size - 1); - if (new_order < MAX_PAGECACHE_ORDER) + if (new_order < mapping_max_folio_order(mapping)) new_order += 2; - new_order = min_t(unsigned int, MAX_PAGECACHE_ORDER, new_order); + new_order = min(mapping_max_folio_order(mapping), new_order); new_order = min_t(unsigned int, new_order, ilog2(ra->size)); /* See comment in page_cache_ra_unbounded() */ -- cgit v1.2.3-58-ga151 From ab95d23bab220ef845c0d422f49452a475330eaf Mon Sep 17 00:00:00 2001 From: Pankaj Raghav Date: Thu, 22 Aug 2024 15:50:10 +0200 Subject: filemap: allocate mapping_min_order folios in the page cache filemap_create_folio() and do_read_cache_folio() were always allocating folio of order 0. __filemap_get_folio was trying to allocate higher order folios when fgp_flags had higher order hint set but it will default to order 0 folio if higher order memory allocation fails. Supporting mapping_min_order implies that we guarantee each folio in the page cache has at least an order of mapping_min_order. When adding new folios to the page cache we must also ensure the index used is aligned to the mapping_min_order as the page cache requires the index to be aligned to the order of the folio. Co-developed-by: Luis Chamberlain Signed-off-by: Luis Chamberlain Signed-off-by: Pankaj Raghav Link: https://lore.kernel.org/r/20240822135018.1931258-3-kernel@pankajraghav.com Tested-by: David Howells Reviewed-by: Hannes Reinecke Reviewed-by: Darrick J. Wong Reviewed-by: Matthew Wilcox (Oracle) Reviewed-by: Daniel Gomez Reviewed-by: Dave Chinner Signed-off-by: Christian Brauner --- include/linux/pagemap.h | 20 ++++++++++++++++++++ mm/filemap.c | 24 ++++++++++++++++-------- 2 files changed, 36 insertions(+), 8 deletions(-) (limited to 'mm') diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index c60025bb584c..4cc170949e9c 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -448,6 +448,26 @@ mapping_min_folio_order(const struct address_space *mapping) return (mapping->flags & AS_FOLIO_ORDER_MIN_MASK) >> AS_FOLIO_ORDER_MIN; } +static inline unsigned long +mapping_min_folio_nrpages(struct address_space *mapping) +{ + return 1UL << mapping_min_folio_order(mapping); +} + +/** + * mapping_align_index() - Align index for this mapping. + * @mapping: The address_space. + * + * The index of a folio must be naturally aligned. If you are adding a + * new folio to the page cache and need to know what index to give it, + * call this function. + */ +static inline pgoff_t mapping_align_index(struct address_space *mapping, + pgoff_t index) +{ + return round_down(index, mapping_min_folio_nrpages(mapping)); +} + /* * Large folio support currently depends on THP. These dependencies are * being worked on but are not yet fixed. diff --git a/mm/filemap.c b/mm/filemap.c index ad5e4a848070..d27e9ac54309 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -859,6 +859,8 @@ noinline int __filemap_add_folio(struct address_space *mapping, VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio); VM_BUG_ON_FOLIO(folio_test_swapbacked(folio), folio); + VM_BUG_ON_FOLIO(folio_order(folio) < mapping_min_folio_order(mapping), + folio); mapping_set_update(&xas, mapping); VM_BUG_ON_FOLIO(index & (folio_nr_pages(folio) - 1), folio); @@ -1919,8 +1921,10 @@ repeat: folio_wait_stable(folio); no_page: if (!folio && (fgp_flags & FGP_CREAT)) { - unsigned order = FGF_GET_ORDER(fgp_flags); + unsigned int min_order = mapping_min_folio_order(mapping); + unsigned int order = max(min_order, FGF_GET_ORDER(fgp_flags)); int err; + index = mapping_align_index(mapping, index); if ((fgp_flags & FGP_WRITE) && mapping_can_writeback(mapping)) gfp |= __GFP_WRITE; @@ -1943,7 +1947,7 @@ no_page: gfp_t alloc_gfp = gfp; err = -ENOMEM; - if (order > 0) + if (order > min_order) alloc_gfp |= __GFP_NORETRY | __GFP_NOWARN; folio = filemap_alloc_folio(alloc_gfp, order); if (!folio) @@ -1958,7 +1962,7 @@ no_page: break; folio_put(folio); folio = NULL; - } while (order-- > 0); + } while (order-- > min_order); if (err == -EEXIST) goto repeat; @@ -2447,13 +2451,15 @@ unlock_mapping: } static int filemap_create_folio(struct file *file, - struct address_space *mapping, pgoff_t index, + struct address_space *mapping, loff_t pos, struct folio_batch *fbatch) { struct folio *folio; int error; + unsigned int min_order = mapping_min_folio_order(mapping); + pgoff_t index; - folio = filemap_alloc_folio(mapping_gfp_mask(mapping), 0); + folio = filemap_alloc_folio(mapping_gfp_mask(mapping), min_order); if (!folio) return -ENOMEM; @@ -2471,6 +2477,7 @@ static int filemap_create_folio(struct file *file, * well to keep locking rules simple. */ filemap_invalidate_lock_shared(mapping); + index = (pos >> (PAGE_SHIFT + min_order)) << min_order; error = filemap_add_folio(mapping, folio, index, mapping_gfp_constraint(mapping, GFP_KERNEL)); if (error == -EEXIST) @@ -2531,8 +2538,7 @@ retry: if (!folio_batch_count(fbatch)) { if (iocb->ki_flags & (IOCB_NOWAIT | IOCB_WAITQ)) return -EAGAIN; - err = filemap_create_folio(filp, mapping, - iocb->ki_pos >> PAGE_SHIFT, fbatch); + err = filemap_create_folio(filp, mapping, iocb->ki_pos, fbatch); if (err == AOP_TRUNCATED_PAGE) goto retry; return err; @@ -3748,9 +3754,11 @@ static struct folio *do_read_cache_folio(struct address_space *mapping, repeat: folio = filemap_get_folio(mapping, index); if (IS_ERR(folio)) { - folio = filemap_alloc_folio(gfp, 0); + folio = filemap_alloc_folio(gfp, + mapping_min_folio_order(mapping)); if (!folio) return ERR_PTR(-ENOMEM); + index = mapping_align_index(mapping, index); err = filemap_add_folio(mapping, folio, index, gfp); if (unlikely(err)) { folio_put(folio); -- cgit v1.2.3-58-ga151 From 26cfdb395eefdb2d34e51184d8466ee04a1618d5 Mon Sep 17 00:00:00 2001 From: Pankaj Raghav Date: Thu, 22 Aug 2024 15:50:11 +0200 Subject: readahead: allocate folios with mapping_min_order in readahead page_cache_ra_unbounded() was allocating single pages (0 order folios) if there was no folio found in an index. Allocate mapping_min_order folios as we need to guarantee the minimum order if it is set. page_cache_ra_order() tries to allocate folio to the page cache with a higher order if the index aligns with that order. Modify it so that the order does not go below the mapping_min_order requirement of the page cache. This function will do the right thing even if the new_order passed is less than the mapping_min_order. When adding new folios to the page cache we must also ensure the index used is aligned to the mapping_min_order as the page cache requires the index to be aligned to the order of the folio. readahead_expand() is called from readahead aops to extend the range of the readahead so this function can assume ractl->_index to be aligned with min_order. Signed-off-by: Pankaj Raghav Co-developed-by: Hannes Reinecke Signed-off-by: Hannes Reinecke Link: https://lore.kernel.org/r/20240822135018.1931258-4-kernel@pankajraghav.com Tested-by: David Howells Acked-by: Darrick J. Wong Reviewed-by: Darrick J. Wong Reviewed-by: Daniel Gomez Reviewed-by: Dave Chinner Reviewed-by: Hannes Reinecke Signed-off-by: Christian Brauner --- mm/readahead.c | 79 +++++++++++++++++++++++++++++++++++++++++++++------------- 1 file changed, 61 insertions(+), 18 deletions(-) (limited to 'mm') diff --git a/mm/readahead.c b/mm/readahead.c index 3e5239e9e177..2078c42777a6 100644 --- a/mm/readahead.c +++ b/mm/readahead.c @@ -206,9 +206,10 @@ void page_cache_ra_unbounded(struct readahead_control *ractl, unsigned long nr_to_read, unsigned long lookahead_size) { struct address_space *mapping = ractl->mapping; - unsigned long index = readahead_index(ractl); + unsigned long ra_folio_index, index = readahead_index(ractl); gfp_t gfp_mask = readahead_gfp_mask(mapping); - unsigned long i; + unsigned long mark, i = 0; + unsigned int min_nrpages = mapping_min_folio_nrpages(mapping); /* * Partway through the readahead operation, we will have added @@ -223,10 +224,24 @@ void page_cache_ra_unbounded(struct readahead_control *ractl, unsigned int nofs = memalloc_nofs_save(); filemap_invalidate_lock_shared(mapping); + index = mapping_align_index(mapping, index); + + /* + * As iterator `i` is aligned to min_nrpages, round_up the + * difference between nr_to_read and lookahead_size to mark the + * index that only has lookahead or "async_region" to set the + * readahead flag. + */ + ra_folio_index = round_up(readahead_index(ractl) + nr_to_read - lookahead_size, + min_nrpages); + mark = ra_folio_index - index; + nr_to_read += readahead_index(ractl) - index; + ractl->_index = index; + /* * Preallocate as many pages as we will need. */ - for (i = 0; i < nr_to_read; i++) { + while (i < nr_to_read) { struct folio *folio = xa_load(&mapping->i_pages, index + i); int ret; @@ -240,12 +255,13 @@ void page_cache_ra_unbounded(struct readahead_control *ractl, * not worth getting one just for that. */ read_pages(ractl); - ractl->_index++; - i = ractl->_index + ractl->_nr_pages - index - 1; + ractl->_index += min_nrpages; + i = ractl->_index + ractl->_nr_pages - index; continue; } - folio = filemap_alloc_folio(gfp_mask, 0); + folio = filemap_alloc_folio(gfp_mask, + mapping_min_folio_order(mapping)); if (!folio) break; @@ -255,14 +271,15 @@ void page_cache_ra_unbounded(struct readahead_control *ractl, if (ret == -ENOMEM) break; read_pages(ractl); - ractl->_index++; - i = ractl->_index + ractl->_nr_pages - index - 1; + ractl->_index += min_nrpages; + i = ractl->_index + ractl->_nr_pages - index; continue; } - if (i == nr_to_read - lookahead_size) + if (i == mark) folio_set_readahead(folio); ractl->_workingset |= folio_test_workingset(folio); - ractl->_nr_pages++; + ractl->_nr_pages += min_nrpages; + i += min_nrpages; } /* @@ -438,13 +455,19 @@ void page_cache_ra_order(struct readahead_control *ractl, struct address_space *mapping = ractl->mapping; pgoff_t start = readahead_index(ractl); pgoff_t index = start; + unsigned int min_order = mapping_min_folio_order(mapping); pgoff_t limit = (i_size_read(mapping->host) - 1) >> PAGE_SHIFT; pgoff_t mark = index + ra->size - ra->async_size; unsigned int nofs; int err = 0; gfp_t gfp = readahead_gfp_mask(mapping); + unsigned int min_ra_size = max(4, mapping_min_folio_nrpages(mapping)); - if (!mapping_large_folio_support(mapping) || ra->size < 4) + /* + * Fallback when size < min_nrpages as each folio should be + * at least min_nrpages anyway. + */ + if (!mapping_large_folio_support(mapping) || ra->size < min_ra_size) goto fallback; limit = min(limit, index + ra->size - 1); @@ -454,10 +477,19 @@ void page_cache_ra_order(struct readahead_control *ractl, new_order = min(mapping_max_folio_order(mapping), new_order); new_order = min_t(unsigned int, new_order, ilog2(ra->size)); + new_order = max(new_order, min_order); /* See comment in page_cache_ra_unbounded() */ nofs = memalloc_nofs_save(); filemap_invalidate_lock_shared(mapping); + /* + * If the new_order is greater than min_order and index is + * already aligned to new_order, then this will be noop as index + * aligned to new_order should also be aligned to min_order. + */ + ractl->_index = mapping_align_index(mapping, index); + index = readahead_index(ractl); + while (index <= limit) { unsigned int order = new_order; @@ -465,7 +497,7 @@ void page_cache_ra_order(struct readahead_control *ractl, if (index & ((1UL << order) - 1)) order = __ffs(index); /* Don't allocate pages past EOF */ - while (index + (1UL << order) - 1 > limit) + while (order > min_order && index + (1UL << order) - 1 > limit) order--; err = ra_alloc_folio(ractl, index, mark, order, gfp); if (err) @@ -703,8 +735,15 @@ void readahead_expand(struct readahead_control *ractl, struct file_ra_state *ra = ractl->ra; pgoff_t new_index, new_nr_pages; gfp_t gfp_mask = readahead_gfp_mask(mapping); + unsigned long min_nrpages = mapping_min_folio_nrpages(mapping); + unsigned int min_order = mapping_min_folio_order(mapping); new_index = new_start / PAGE_SIZE; + /* + * Readahead code should have aligned the ractl->_index to + * min_nrpages before calling readahead aops. + */ + VM_BUG_ON(!IS_ALIGNED(ractl->_index, min_nrpages)); /* Expand the leading edge downwards */ while (ractl->_index > new_index) { @@ -714,9 +753,11 @@ void readahead_expand(struct readahead_control *ractl, if (folio && !xa_is_value(folio)) return; /* Folio apparently present */ - folio = filemap_alloc_folio(gfp_mask, 0); + folio = filemap_alloc_folio(gfp_mask, min_order); if (!folio) return; + + index = mapping_align_index(mapping, index); if (filemap_add_folio(mapping, folio, index, gfp_mask) < 0) { folio_put(folio); return; @@ -726,7 +767,7 @@ void readahead_expand(struct readahead_control *ractl, ractl->_workingset = true; psi_memstall_enter(&ractl->_pflags); } - ractl->_nr_pages++; + ractl->_nr_pages += min_nrpages; ractl->_index = folio->index; } @@ -741,9 +782,11 @@ void readahead_expand(struct readahead_control *ractl, if (folio && !xa_is_value(folio)) return; /* Folio apparently present */ - folio = filemap_alloc_folio(gfp_mask, 0); + folio = filemap_alloc_folio(gfp_mask, min_order); if (!folio) return; + + index = mapping_align_index(mapping, index); if (filemap_add_folio(mapping, folio, index, gfp_mask) < 0) { folio_put(folio); return; @@ -753,10 +796,10 @@ void readahead_expand(struct readahead_control *ractl, ractl->_workingset = true; psi_memstall_enter(&ractl->_pflags); } - ractl->_nr_pages++; + ractl->_nr_pages += min_nrpages; if (ra) { - ra->size++; - ra->async_size++; + ra->size += min_nrpages; + ra->async_size += min_nrpages; } } } -- cgit v1.2.3-58-ga151 From e220917fa50774fedb27c075df2261fd664e8ca3 Mon Sep 17 00:00:00 2001 From: Luis Chamberlain Date: Thu, 22 Aug 2024 15:50:12 +0200 Subject: mm: split a folio in minimum folio order chunks split_folio() and split_folio_to_list() assume order 0, to support minorder for non-anonymous folios, we must expand these to check the folio mapping order and use that. Set new_order to be at least minimum folio order if it is set in split_huge_page_to_list() so that we can maintain minimum folio order requirement in the page cache. Update the debugfs write files used for testing to ensure the order is respected as well. We simply enforce the min order when a file mapping is used. Signed-off-by: Luis Chamberlain Signed-off-by: Pankaj Raghav Link: https://lore.kernel.org/r/20240902124931.506061-2-kernel@pankajraghav.com # folded fix Link: https://lore.kernel.org/r/20240822135018.1931258-5-kernel@pankajraghav.com Tested-by: David Howells Reviewed-by: Hannes Reinecke Reviewed-by: Zi Yan Signed-off-by: Christian Brauner --- include/linux/huge_mm.h | 28 ++++++++++++++++++--- mm/huge_memory.c | 65 ++++++++++++++++++++++++++++++++++++++++++++++--- 2 files changed, 85 insertions(+), 8 deletions(-) (limited to 'mm') diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h index e25d9ebfdf89..7a570e0437c9 100644 --- a/include/linux/huge_mm.h +++ b/include/linux/huge_mm.h @@ -96,6 +96,8 @@ extern struct kobj_attribute thpsize_shmem_enabled_attr; #define thp_vma_allowable_order(vma, vm_flags, tva_flags, order) \ (!!thp_vma_allowable_orders(vma, vm_flags, tva_flags, BIT(order))) +#define split_folio(f) split_folio_to_list(f, NULL) + #ifdef CONFIG_PGTABLE_HAS_HUGE_LEAVES #define HPAGE_PMD_SHIFT PMD_SHIFT #define HPAGE_PUD_SHIFT PUD_SHIFT @@ -317,9 +319,24 @@ unsigned long thp_get_unmapped_area_vmflags(struct file *filp, unsigned long add bool can_split_folio(struct folio *folio, int *pextra_pins); int split_huge_page_to_list_to_order(struct page *page, struct list_head *list, unsigned int new_order); +int min_order_for_split(struct folio *folio); +int split_folio_to_list(struct folio *folio, struct list_head *list); static inline int split_huge_page(struct page *page) { - return split_huge_page_to_list_to_order(page, NULL, 0); + 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); } void deferred_split_folio(struct folio *folio); @@ -484,6 +501,12 @@ static inline int split_huge_page(struct page *page) { return 0; } + +static inline int split_folio_to_list(struct folio *folio, struct list_head *list) +{ + return 0; +} + static inline void deferred_split_folio(struct folio *folio) {} #define split_huge_pmd(__vma, __pmd, __address) \ do { } while (0) @@ -598,7 +621,4 @@ static inline int split_folio_to_order(struct folio *folio, int new_order) return split_folio_to_list_to_order(folio, NULL, new_order); } -#define split_folio_to_list(f, l) split_folio_to_list_to_order(f, l, 0) -#define split_folio(f) split_folio_to_order(f, 0) - #endif /* _LINUX_HUGE_MM_H */ diff --git a/mm/huge_memory.c b/mm/huge_memory.c index f4be468e06a4..9931ff1d9a9d 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -3082,6 +3082,9 @@ bool can_split_folio(struct folio *folio, int *pextra_pins) * released, or if some unexpected race happened (e.g., anon VMA disappeared, * truncation). * + * Callers should ensure that the order respects the address space mapping + * min-order if one is set for non-anonymous folios. + * * Returns -EINVAL when trying to split to an order that is incompatible * with the folio. Splitting to order 0 is compatible with all folios. */ @@ -3163,6 +3166,7 @@ int split_huge_page_to_list_to_order(struct page *page, struct list_head *list, mapping = NULL; anon_vma_lock_write(anon_vma); } else { + unsigned int min_order; gfp_t gfp; mapping = folio->mapping; @@ -3173,6 +3177,14 @@ int split_huge_page_to_list_to_order(struct page *page, struct list_head *list, goto out; } + 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; + } + gfp = current_gfp_context(mapping_gfp_mask(mapping) & GFP_RECLAIM_MASK); @@ -3285,6 +3297,30 @@ out: return ret; } +int min_order_for_split(struct folio *folio) +{ + if (folio_test_anon(folio)) + return 0; + + if (!folio->mapping) { + if (folio_test_pmd_mappable(folio)) + count_vm_event(THP_SPLIT_PAGE_FAILED); + return -EBUSY; + } + + return mapping_min_folio_order(folio->mapping); +} + +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); +} + void __folio_undo_large_rmappable(struct folio *folio) { struct deferred_split *ds_queue; @@ -3515,6 +3551,8 @@ static int split_huge_pages_pid(int pid, unsigned long vaddr_start, struct vm_area_struct *vma = vma_lookup(mm, addr); struct page *page; struct folio *folio; + struct address_space *mapping; + unsigned int target_order = new_order; if (!vma) break; @@ -3535,7 +3573,13 @@ static int split_huge_pages_pid(int pid, unsigned long vaddr_start, if (!is_transparent_hugepage(folio)) goto next; - if (new_order >= folio_order(folio)) + if (!folio_test_anon(folio)) { + mapping = folio->mapping; + target_order = max(new_order, + mapping_min_folio_order(mapping)); + } + + if (target_order >= folio_order(folio)) goto next; total++; @@ -3551,9 +3595,14 @@ static int split_huge_pages_pid(int pid, unsigned long vaddr_start, if (!folio_trylock(folio)) goto next; - if (!split_folio_to_order(folio, new_order)) + if (!folio_test_anon(folio) && folio->mapping != mapping) + goto unlock; + + if (!split_folio_to_order(folio, target_order)) split++; +unlock: + folio_unlock(folio); next: folio_put(folio); @@ -3578,6 +3627,8 @@ static int split_huge_pages_in_file(const char *file_path, pgoff_t off_start, pgoff_t index; int nr_pages = 1; unsigned long total = 0, split = 0; + unsigned int min_order; + unsigned int target_order; file = getname_kernel(file_path); if (IS_ERR(file)) @@ -3591,6 +3642,8 @@ static int split_huge_pages_in_file(const char *file_path, pgoff_t off_start, file_path, off_start, off_end); mapping = candidate->f_mapping; + min_order = mapping_min_folio_order(mapping); + target_order = max(new_order, min_order); for (index = off_start; index < off_end; index += nr_pages) { struct folio *folio = filemap_get_folio(mapping, index); @@ -3605,15 +3658,19 @@ static int split_huge_pages_in_file(const char *file_path, pgoff_t off_start, total++; nr_pages = folio_nr_pages(folio); - if (new_order >= folio_order(folio)) + if (target_order >= folio_order(folio)) goto next; if (!folio_trylock(folio)) goto next; - if (!split_folio_to_order(folio, new_order)) + if (folio->mapping != mapping) + goto unlock; + + if (!split_folio_to_order(folio, target_order)) split++; +unlock: folio_unlock(folio); next: folio_put(folio); -- cgit v1.2.3-58-ga151 From 743a2753a02e805347969f6f89f38b736850d808 Mon Sep 17 00:00:00 2001 From: Pankaj Raghav Date: Thu, 22 Aug 2024 15:50:13 +0200 Subject: filemap: cap PTE range to be created to allowed zero fill in folio_map_range() Usually the page cache does not extend beyond the size of the inode, therefore, no PTEs are created for folios that extend beyond the size. But with LBS support, we might extend page cache beyond the size of the inode as we need to guarantee folios of minimum order. While doing a read, do_fault_around() can create PTEs for pages that lie beyond the EOF leading to incorrect error return when accessing a page beyond the mapped file. Cap the PTE range to be created for the page cache up to the end of file(EOF) in filemap_map_pages() so that return error codes are consistent with POSIX[1] for LBS configurations. generic/749 has been created to trigger this edge case. This also fixes generic/749 for tmpfs with huge=always on systems with 4k base page size. [1](from mmap(2)) SIGBUS Attempted access to a page of the buffer that lies beyond the end of the mapped file. For an explanation of the treatment of the bytes in the page that corresponds to the end of a mapped file that is not a multiple of the page size, see NOTES. Signed-off-by: Luis Chamberlain Signed-off-by: Pankaj Raghav Link: https://lore.kernel.org/r/20240822135018.1931258-6-kernel@pankajraghav.com Tested-by: David Howells Acked-by: Darrick J. Wong Reviewed-by: Hannes Reinecke Reviewed-by: Matthew Wilcox (Oracle) Reviewed-by: Darrick J. Wong Reviewed-by: Daniel Gomez Reviewed-by: Dave Chinner Signed-off-by: Christian Brauner --- mm/filemap.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'mm') diff --git a/mm/filemap.c b/mm/filemap.c index d27e9ac54309..d32210927453 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -3608,7 +3608,7 @@ vm_fault_t filemap_map_pages(struct vm_fault *vmf, struct vm_area_struct *vma = vmf->vma; struct file *file = vma->vm_file; struct address_space *mapping = file->f_mapping; - pgoff_t last_pgoff = start_pgoff; + pgoff_t file_end, last_pgoff = start_pgoff; unsigned long addr; XA_STATE(xas, &mapping->i_pages, start_pgoff); struct folio *folio; @@ -3634,6 +3634,10 @@ vm_fault_t filemap_map_pages(struct vm_fault *vmf, 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; -- cgit v1.2.3-58-ga151