From: Namjae Jeon <namjae.jeon@xxxxxxxxxxx> linux-v3.8-rc1 and later support for plug for blkdev_issue_discard with commit 0cfbcafcae8b7364b5fa96c2b26ccde7a3a296a9 (block: add plug for blkdev_issue_discard ) For example, 1) DISCARD rq-1 with size size 4GB 2) DISCARD rq-2 with size size 1GB If these 2 discard requests get merged, final request size will be 5GB. In this case, request's __data_len field may overflow as it can store max 4GB(unsigned int). This issue was observed while doing mkfs.f2fs on 5GB SD card: https://lkml.org/lkml/2013/4/1/292 # mkfs.f2fs /dev/mmcblk0p3 Info: sector size = 512 Info: total sectors = 11370496 (in 512bytes) Info: zone aligned segment0 blkaddr: 512 [ 257.789764] blk_update_request: bio idx 0 >= vcnt 0 mkfs process gets stuck in D state and I see the following in the dmesg: [ 257.789733] __end_that: dev mmcblk0: type=1, flags=122c8081 [ 257.789764] sector 4194304, nr/cnr 2981888/4294959104 [ 257.789764] bio df3840c0, biotail df3848c0, buffer (null), len 1526726656 [ 257.789764] blk_update_request: bio idx 0 >= vcnt 0 [ 257.794921] request botched: dev mmcblk0: type=1, flags=122c8081 [ 257.794921] sector 4194304, nr/cnr 2981888/4294959104 [ 257.794921] bio df3840c0, biotail df3848c0, buffer (null), len 1526726656 Few drivers(e.g. mmc, mtd..) set q->limits.max_discard_sectors more than UINT_MAX >> 9 sectors which is incorrect and it may lead to overflow of request's __data_len field if merged discard request's size exceeds 4GB. This patchset fixes this issue by updating helper function blk_queue_max_discard_sectors which is used to set max_discard_sectors limit. This patchset also replaces "q->limits.max_discard_sector = max_discard_sectors" with blk_queue_max_discard_sectors call in other drivers like mmc, mtd etc. Namjae Jeon (9): block: fix max discard sectors limit mmc: fix max_discard_sectors sd: use generic helper to set max_discard_sectors mtd: use generic helper to set max_discard_sectors loop: use generic helper to set max_discard_sectors nbd: use generic helper to set max_discard_sectors brd: use generic helper to set max_discard_sectors dm thin: use generic helper to set max_discard_sectors bcache: use generic helper to set max_discard_sectors -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
