diff options
| author | Sergey Senozhatsky <senozhatsky@chromium.org> | 2026-01-07 14:21:44 +0900 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2026-01-26 20:02:25 -0800 |
| commit | 0be909f114c4e82a4fe5964851af1ab8889dc76c (patch) | |
| tree | 865d722060c1227c2f0b3956a7d1d483c982af7a /drivers/block | |
| parent | 95296536eb19c969e91684287cf3bfcb382221d3 (diff) | |
zsmalloc: use actual object size to detect spans
Using class->size to detect spanning objects is not entirely correct,
because some size classes can hold a range of object sizes of up to
class->size bytes in length, due to size-classes merge. Such classes use
padding for cases when actually written objects are smaller than
class->size. zs_obj_read_begin() can incorrectly hit the slow path and
perform memcpy of such objects, basically copying padding bytes. Instead
of class->size zs_obj_read_begin() should use the actual compressed object
length (both zram and zswap know it) so that it can correctly handle
situations when a written object is small enough to fit into the first
physical page.
Link: https://lkml.kernel.org/r/20260107052145.3586917-1-senozhatsky@chromium.org
Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Reviewed-by: Yosry Ahmed <yosry.ahmed@linux.dev> [zsmalloc & zswap]
Reviewed-by: Nhat Pham <nphamcs@gmail.com>
Cc: Brian Geffon <bgeffon@google.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'drivers/block')
| -rw-r--r-- | drivers/block/zram/zram_drv.c | 14 |
1 files changed, 8 insertions, 6 deletions
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 1d6760b3b557..f92845ef9192 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -2062,11 +2062,11 @@ static int read_incompressible_page(struct zram *zram, struct page *page, void *src, *dst; handle = get_slot_handle(zram, index); - src = zs_obj_read_begin(zram->mem_pool, handle, NULL); + src = zs_obj_read_begin(zram->mem_pool, handle, PAGE_SIZE, NULL); dst = kmap_local_page(page); copy_page(dst, src); kunmap_local(dst); - zs_obj_read_end(zram->mem_pool, handle, src); + zs_obj_read_end(zram->mem_pool, handle, PAGE_SIZE, src); return 0; } @@ -2084,11 +2084,12 @@ static int read_compressed_page(struct zram *zram, struct page *page, u32 index) prio = get_slot_comp_priority(zram, index); zstrm = zcomp_stream_get(zram->comps[prio]); - src = zs_obj_read_begin(zram->mem_pool, handle, zstrm->local_copy); + src = zs_obj_read_begin(zram->mem_pool, handle, size, + zstrm->local_copy); dst = kmap_local_page(page); ret = zcomp_decompress(zram->comps[prio], zstrm, src, size, dst); kunmap_local(dst); - zs_obj_read_end(zram->mem_pool, handle, src); + zs_obj_read_end(zram->mem_pool, handle, size, src); zcomp_stream_put(zstrm); return ret; @@ -2111,9 +2112,10 @@ static int read_from_zspool_raw(struct zram *zram, struct page *page, u32 index) * takes place here, as we read raw compressed data. */ zstrm = zcomp_stream_get(zram->comps[ZRAM_PRIMARY_COMP]); - src = zs_obj_read_begin(zram->mem_pool, handle, zstrm->local_copy); + src = zs_obj_read_begin(zram->mem_pool, handle, size, + zstrm->local_copy); memcpy_to_page(page, 0, src, size); - zs_obj_read_end(zram->mem_pool, handle, src); + zs_obj_read_end(zram->mem_pool, handle, size, src); zcomp_stream_put(zstrm); return 0; |