KMSAN doesn't allow treating adjacent memory pages as such, if they were allocated by different alloc_pages() calls. ext4_mpage_readpages() however does so: adjacent pages end up being passed together to dma_direct_map_sg(). To prevent this, jump directly to the buffer_head-based read function in KMSAN builds. Signed-off-by: Alexander Potapenko <glider@xxxxxxxxxx> Cc: "Theodore Ts'o" <tytso@xxxxxxx> Cc: Andreas Dilger <adilger.kernel@xxxxxxxxx> Cc: Vegard Nossum <vegard.nossum@xxxxxxxxxx> Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx> Cc: linux-mm@xxxxxxxxx --- Change-Id: I54ae8af536626a988e6398ff18a06c179b0ce034 --- fs/ext4/readpage.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/fs/ext4/readpage.c b/fs/ext4/readpage.c index a30b203fa461..a3bb9e3ce5de 100644 --- a/fs/ext4/readpage.c +++ b/fs/ext4/readpage.c @@ -252,6 +252,17 @@ int ext4_mpage_readpages(struct address_space *mapping, if (page_has_buffers(page)) goto confused; +#if defined(CONFIG_KMSAN) + /* + * The following code may treat adjacent pages allocated + * separately as a bigger contiguous allocation. + * KMSAN doesn't allow this, as the corresponding metadata + * pages may be separated. + * Skip this complex logic for KMSAN builds. + */ + goto confused; +#endif + block_in_file = (sector_t)page->index << (PAGE_SHIFT - blkbits); last_block = block_in_file + nr_pages * blocks_per_page; last_block_in_file = (ext4_readpage_limit(inode) + -- 2.24.0.432.g9d3f5f5b63-goog
