From 0669d2b265d0f6f9e16f1abbf5c5d2e22b219a6b Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Mon, 19 Oct 2020 12:13:53 +0200 Subject: zram: Fix __zram_bvec_{read,write}() locking order Mikhail reported a lockdep spat detailing how __zram_bvec_read() and __zram_bvec_write() use zstrm->lock and zspage->lock in opposite order. Reported-by: Mikhail Gavrilov Signed-off-by: Peter Zijlstra (Intel) Tested-by: Mikhail Gavrilov Acked-by: Minchan Kim Acked-by: Sebastian Andrzej Siewior Signed-off-by: Jens Axboe --- drivers/block/zram/zram_drv.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) (limited to 'drivers/block/zram') diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index bff3d4021c18..e13201424ba2 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -1218,10 +1218,11 @@ out: static int __zram_bvec_read(struct zram *zram, struct page *page, u32 index, struct bio *bio, bool partial_io) { - int ret; + struct zcomp_strm *zstrm; unsigned long handle; unsigned int size; void *src, *dst; + int ret; zram_slot_lock(zram, index); if (zram_test_flag(zram, index, ZRAM_WB)) { @@ -1252,6 +1253,9 @@ static int __zram_bvec_read(struct zram *zram, struct page *page, u32 index, size = zram_get_obj_size(zram, index); + if (size != PAGE_SIZE) + zstrm = zcomp_stream_get(zram->comp); + src = zs_map_object(zram->mem_pool, handle, ZS_MM_RO); if (size == PAGE_SIZE) { dst = kmap_atomic(page); @@ -1259,8 +1263,6 @@ static int __zram_bvec_read(struct zram *zram, struct page *page, u32 index, kunmap_atomic(dst); ret = 0; } else { - struct zcomp_strm *zstrm = zcomp_stream_get(zram->comp); - dst = kmap_atomic(page); ret = zcomp_decompress(zstrm, src, size, dst); kunmap_atomic(dst); -- cgit v1.2.3