zram_rw_page returns error code to upper layer with PG_error flag of the page but it should be wrong usage. If submitted IO is hard fail(ie, I/O again will not succeed), we should return 0, indicating that the submission was successful but the IO operation failed. http://marc.info/?l=linux-mm&m=141511693112734&w=2 This patch fixes below BUG. [ 179.987592] zram0: detected capacity change from 2147483648 to 0 [ 179.987570] page:ffffea00008d6300 count:2 mapcount:0 mapping:ffff880025348e88 index:0x0 [ 179.987570] flags: 0x100000000020002(error|mappedtodisk) [ 179.987570] page dumped because: VM_BUG_ON_PAGE(!PageLocked(page)) [ 179.987570] ------------[ cut here ]------------ [ 179.987570] kernel BUG at mm/filemap.c:747! [ 179.987570] invalid opcode: 0000 [#1] SMP [ 179.987570] Dumping ftrace buffer: [ 179.987570] (ftrace buffer empty) [ 179.987570] Modules linked in: [ 179.987570] CPU: 10 PID: 23080 Comm: udisks-part-id Not tainted 3.18.0-rc2+ #584 [ 179.987570] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 [ 179.987570] task: ffff88001de74200 ti: ffff88001b220000 task.ti: ffff88001b220000 [ 179.987570] RIP: 0010:[<ffffffff8114ae12>] [<ffffffff8114ae12>] unlock_page+0x82/0x90 [ 179.987570] RSP: 0018:ffff88001b223998 EFLAGS: 00010246 [ 179.987570] RAX: 0000000000000036 RBX: ffff88001e009a50 RCX: 000000000910090f [ 179.987570] RDX: 0000000000000910 RSI: 0000000000000001 RDI: ffffffff81600a7f [ 179.987570] RBP: ffff88001b223998 R08: 0000000000000001 R09: 0000000000000001 [ 179.987570] R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000001 [ 179.987570] R13: ffff88001e0099c0 R14: 00000000fffffffb R15: ffff88001e0099c0 [ 179.987570] FS: 00007fcb17c73800(0000) GS:ffff880027f40000(0000) knlGS:0000000000000000 [ 179.987570] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b [ 179.987570] CR2: 00007fff1629ebc8 CR3: 000000001dc4f000 CR4: 00000000000006e0 [ 179.987570] Stack: [ 179.987570] ffff88001b2239a8 ffffffff8114afde ffff88001b2239d8 ffffffff811f2e52 [ 179.987570] ffff88001e0099c0 00000000fffffffb 0000000000000000 ffff880025348e88 [ 179.987570] ffff88001b223a08 ffffffff812e9ad3 ffff88001b223a08 ffffffff8109b6b3 [ 179.987570] Call Trace: [ 179.987570] [<ffffffff8114afde>] page_endio+0x1e/0x80 [ 179.987570] [<ffffffff811f2e52>] mpage_end_io+0x42/0x60 [ 179.987570] [<ffffffff812e9ad3>] bio_endio+0x53/0xa0 [ 179.987570] [<ffffffff8109b6b3>] ? up_read+0x23/0x40 [ 179.987570] [<ffffffff81413f09>] zram_make_request+0x2a9/0x3c0 [ 179.987570] [<ffffffff812ee330>] generic_make_request+0xc0/0x100 [ 179.987570] [<ffffffff812ee3e5>] submit_bio+0x75/0x140 [ 179.987570] [<ffffffff812ee375>] ? submit_bio+0x5/0x140 [ 179.987570] [<ffffffff811f2e03>] mpage_bio_submit+0x33/0x40 [ 179.987570] [<ffffffff811f3de5>] mpage_readpages+0xf5/0x110 [ 179.987570] [<ffffffff811ed7a0>] ? I_BDEV+0x10/0x10 [ 179.987570] [<ffffffff811ed7a0>] ? I_BDEV+0x10/0x10 [ 179.987570] [<ffffffff81603241>] ? ftrace_call+0x5/0x2f [ 179.987570] [<ffffffff81603241>] ? ftrace_call+0x5/0x2f [ 179.987570] [<ffffffff811ee190>] ? blkdev_write_begin+0x30/0x30 [ 179.987570] [<ffffffff811ed7a0>] ? I_BDEV+0x10/0x10 [ 179.987570] [<ffffffff811ee1ad>] blkdev_readpages+0x1d/0x20 [ 179.987570] [<ffffffff81158ed4>] __do_page_cache_readahead+0x204/0x290 [ 179.987570] [<ffffffff81158d99>] ? __do_page_cache_readahead+0xc9/0x290 [ 179.987570] [<ffffffff8114b045>] ? find_get_entry+0x5/0x130 [ 179.987570] [<ffffffff811593cd>] force_page_cache_readahead+0x7d/0xb0 [ 179.987570] [<ffffffff81159443>] page_cache_sync_readahead+0x43/0x50 [ 179.987570] [<ffffffff8114d0e1>] generic_file_read_iter+0x451/0x650 [ 179.987570] [<ffffffff81603241>] ? ftrace_call+0x5/0x2f [ 179.987570] [<ffffffff811ed947>] blkdev_read_iter+0x37/0x40 [ 179.987570] [<ffffffff811b4358>] new_sync_read+0x78/0xb0 [ 179.987570] [<ffffffff811b555b>] vfs_read+0xab/0x180 [ 179.987570] [<ffffffff811b5682>] SyS_read+0x52/0xb0 [ 179.987570] [<ffffffff816011d2>] system_call_fastpath+0x12/0x17 [ 179.987570] Code: 00 4c 8b 82 f8 00 00 00 31 d2 48 d3 ee 48 8d 3c f6 48 89 c6 49 8d 3c f8 e8 dc 9f f4 ff 5d c3 48 c7 c6 88 2c a0 81 e8 1e a8 02 00 <0f> 0b 66 66 66 2e 0f 1f 84 00 00 00 00 00 e8 bb 83 4b 00 55 48 [ 179.987570] RIP [<ffffffff8114ae12>] unlock_page+0x82/0x90 [ 179.987570] RSP <ffff88001b223998> [ 179.987570] ---[ end trace 39c73c1d9da87ec4 ]--- [ 180.030327] zram0: detected capacity change from 0 to 2147483648 [ 180.033795] Adding 2097148k swap on /dev/zram0. Priority:-1 extents:1 across:2097148k SSFS [ 181.978291] zram_kern_compi (2685): drop_caches: 3 Cc: Matthew Wilcox <willy@xxxxxxxxxxxxxxx> Cc: Dave Chinner <david@xxxxxxxxxxxxx> Cc: Karam Lee <karam.lee@xxxxxxx> Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx> --- drivers/block/zram/zram_drv.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-) diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 05e8e54551de..004d758f0c39 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -947,7 +947,7 @@ static void zram_slot_free_notify(struct block_device *bdev, static int zram_rw_page(struct block_device *bdev, sector_t sector, struct page *page, int rw) { - int offset, ret; + int offset, err; u32 index; struct zram *zram; struct bio_vec bv; @@ -955,13 +955,13 @@ static int zram_rw_page(struct block_device *bdev, sector_t sector, zram = bdev->bd_disk->private_data; if (!valid_io_request(zram, sector, PAGE_SIZE)) { atomic64_inc(&zram->stats.invalid_io); - ret = -EINVAL; + err = -EINVAL; goto out; } down_read(&zram->init_lock); if (unlikely(!init_done(zram))) { - ret = -EIO; + err = -EIO; goto out_unlock; } @@ -972,13 +972,18 @@ static int zram_rw_page(struct block_device *bdev, sector_t sector, bv.bv_len = PAGE_SIZE; bv.bv_offset = 0; - ret = zram_bvec_rw(zram, &bv, index, offset, rw); + err = zram_bvec_rw(zram, &bv, index, offset, rw); out_unlock: up_read(&zram->init_lock); out: - page_endio(page, rw, ret); - return ret; + page_endio(page, rw, err); + + /* + * Return 0 prevents I/O fallback trial caused by rw_page fail + * and upper layer can handle this IO error via page error. + */ + return 0; } static const struct block_device_operations zram_devops = { -- 2.0.0 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. 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