From: Lorenzo Stoakes Date: Fri, 19 Jun 2026 11:28:51 +0000 (+0100) Subject: Revert "mm: limit filemap_fault readahead to VMA boundaries" X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=13a1e1a618858407fa12c391f664ea750651f6b2;p=thirdparty%2Flinux.git Revert "mm: limit filemap_fault readahead to VMA boundaries" This reverts commit 7b32f64bc512b40b268776c5ac4d354b325b3197. This patch caused a significant performance regression, so revert it, and we can determine whether the approach is sensible or not moving forwards, and if so how to avoid this. There was a merge conflict with commit de97ae6222c1 ("mm/readahead: no PG_readahead on EOF"), care was taken to ensure that the revert retained the behaviour of this patch and cleanly reverts commit 7b32f64bc512 ("mm: limit filemap_fault readahead to VMA boundaries") only. Link: https://lore.kernel.org/20260619112852.104213-1-ljs@kernel.org Fixes: 7b32f64bc512 ("mm: limit filemap_fault readahead to VMA boundaries") Signed-off-by: Lorenzo Stoakes Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-lkp/202606181547.617a6967-lkp@intel.com Acked-by: David Hildenbrand (Arm) Reviewed-by: Pedro Falcato Reviewed-by: Matthew Wilcox (Oracle) Cc: Jan Kara Cc: Kalesh Singh Signed-off-by: Andrew Morton --- diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index 627771e82eb16..2c3718d592d6d 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -1348,7 +1348,6 @@ struct readahead_control { struct file_ra_state *ra; /* private: use the readahead_* accessors instead */ pgoff_t _index; - pgoff_t _max_index; /* limit readahead to _max_index, inclusive */ unsigned int _nr_pages; unsigned int _batch_count; bool dropbehind; @@ -1362,7 +1361,6 @@ struct readahead_control { .mapping = m, \ .ra = r, \ ._index = i, \ - ._max_index = ULONG_MAX, \ } #define VM_READAHEAD_PAGES (SZ_128K / PAGE_SIZE) diff --git a/mm/filemap.c b/mm/filemap.c index dc3a0e960b9fd..17a64837597cb 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -3312,8 +3312,6 @@ static struct file *do_sync_mmap_readahead(struct vm_fault *vmf) unsigned int thp_order = 0; unsigned short mmap_miss; - ractl._max_index = vmf->vma->vm_pgoff + vma_pages(vmf->vma) - 1; - /* Use the readahead code, even if readahead is disabled */ if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && (vm_flags & VM_HUGEPAGE)) { /* @@ -3409,7 +3407,6 @@ static struct file *do_sync_mmap_readahead(struct vm_fault *vmf) * mmap read-around */ ra->start = max_t(long, 0, vmf->pgoff - ra->ra_pages / 2); - ra->start = max(ra->start, vmf->vma->vm_pgoff); ra->size = ra->ra_pages; ra->async_size = ra->ra_pages / 4; ra->order = 0; @@ -3457,7 +3454,6 @@ static struct file *do_async_mmap_readahead(struct vm_fault *vmf, } if (folio_test_readahead(folio)) { - ractl._max_index = vmf->vma->vm_pgoff + vma_pages(vmf->vma) - 1; fpin = maybe_unlock_mmap_for_io(vmf, fpin); page_cache_async_ra(&ractl, folio, ra->ra_pages); } diff --git a/mm/readahead.c b/mm/readahead.c index 38ce16e3fcbdf..558c92957518b 100644 --- a/mm/readahead.c +++ b/mm/readahead.c @@ -335,8 +335,6 @@ static void do_page_cache_ra(struct readahead_control *ractl, return; end_index = (isize - 1) >> PAGE_SHIFT; - if (end_index > ractl->_max_index) - end_index = ractl->_max_index; if (index > end_index) return; /* Don't read past the page containing the last byte of the file */ @@ -487,7 +485,7 @@ void page_cache_ra_order(struct readahead_control *ractl, pgoff_t start = readahead_index(ractl); pgoff_t index = start; unsigned int min_order = mapping_min_folio_order(mapping); - pgoff_t limit; + pgoff_t limit = (i_size_read(mapping->host) - 1) >> PAGE_SHIFT; pgoff_t mark; unsigned int nofs; int err = 0; @@ -500,8 +498,6 @@ void page_cache_ra_order(struct readahead_control *ractl, goto fallback; } - limit = (i_size_read(mapping->host) - 1) >> PAGE_SHIFT; - limit = min(limit, ractl->_max_index); if (limit > index + ra->size - 1) { limit = index + ra->size - 1; mark = index + ra->size - ra->async_size;