6.9-stable review patch. If anyone has any objections, please let me know.
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From: Gavin Shan gshan@redhat.com
commit 1f789a45c3f1aa77531db21768fca70b66c0eeb1 upstream.
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@redhat.com Acked-by: David Hildenbrand david@redhat.com Cc: Darrick J. Wong djwong@kernel.org Cc: Don Dutile ddutile@redhat.com Cc: Hugh Dickins hughd@google.com Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Matthew Wilcox (Oracle) willy@infradead.org Cc: Ryan Roberts ryan.roberts@arm.com Cc: William Kucharski william.kucharski@oracle.com Cc: Zhenyu Zhang zhenyzha@redhat.com Cc: stable@vger.kernel.org [5.18+] Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- mm/readahead.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
--- a/mm/readahead.c +++ b/mm/readahead.c @@ -499,11 +499,11 @@ 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();