• David Sloan's avatar
    md/raid5: Remove unnecessary bio_put() in raid5_read_one_chunk() · c66a6f41
    David Sloan authored
    When running chunk-sized reads on disks with badblocks duplicate bio
    free/puts are observed:
    
       =============================================================================
       BUG bio-200 (Not tainted): Object already free
       -----------------------------------------------------------------------------
       Allocated in mempool_alloc_slab+0x17/0x20 age=3 cpu=2 pid=7504
        __slab_alloc.constprop.0+0x5a/0xb0
        kmem_cache_alloc+0x31e/0x330
        mempool_alloc_slab+0x17/0x20
        mempool_alloc+0x100/0x2b0
        bio_alloc_bioset+0x181/0x460
        do_mpage_readpage+0x776/0xd00
        mpage_readahead+0x166/0x320
        blkdev_readahead+0x15/0x20
        read_pages+0x13f/0x5f0
        page_cache_ra_unbounded+0x18d/0x220
        force_page_cache_ra+0x181/0x1c0
        page_cache_sync_ra+0x65/0xb0
        filemap_get_pages+0x1df/0xaf0
        filemap_read+0x1e1/0x700
        blkdev_read_iter+0x1e5/0x330
        vfs_read+0x42a/0x570
       Freed in mempool_free_slab+0x17/0x20 age=3 cpu=2 pid=7504
        kmem_cache_free+0x46d/0x490
        mempool_free_slab+0x17/0x20
        mempool_free+0x66/0x190
        bio_free+0x78/0x90
        bio_put+0x100/0x1a0
        raid5_make_request+0x2259/0x2450
        md_handle_request+0x402/0x600
        md_submit_bio+0xd9/0x120
        __submit_bio+0x11f/0x1b0
        submit_bio_noacct_nocheck+0x204/0x480
        submit_bio_noacct+0x32e/0xc70
        submit_bio+0x98/0x1a0
        mpage_readahead+0x250/0x320
        blkdev_readahead+0x15/0x20
        read_pages+0x13f/0x5f0
        page_cache_ra_unbounded+0x18d/0x220
       Slab 0xffffea000481b600 objects=21 used=0 fp=0xffff8881206d8940 flags=0x17ffffc0010201(locked|slab|head|node=0|zone=2|lastcpupid=0x1fffff)
       CPU: 0 PID: 34525 Comm: kworker/u24:2 Not tainted 6.0.0-rc2-localyes-265166-gf11c5343fa3f #143
       Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-1ubuntu1.1 04/01/2014
       Workqueue: raid5wq raid5_do_work
       Call Trace:
        <TASK>
        dump_stack_lvl+0x5a/0x78
        dump_stack+0x10/0x16
        print_trailer+0x158/0x165
        object_err+0x35/0x50
        free_debug_processing.cold+0xb7/0xbe
        __slab_free+0x1ae/0x330
        kmem_cache_free+0x46d/0x490
        mempool_free_slab+0x17/0x20
        mempool_free+0x66/0x190
        bio_free+0x78/0x90
        bio_put+0x100/0x1a0
        mpage_end_io+0x36/0x150
        bio_endio+0x2fd/0x360
        md_end_io_acct+0x7e/0x90
        bio_endio+0x2fd/0x360
        handle_failed_stripe+0x960/0xb80
        handle_stripe+0x1348/0x3760
        handle_active_stripes.constprop.0+0x72a/0xaf0
        raid5_do_work+0x177/0x330
        process_one_work+0x616/0xb20
        worker_thread+0x2bd/0x6f0
        kthread+0x179/0x1b0
        ret_from_fork+0x22/0x30
        </TASK>
    
    The double free is caused by an unnecessary bio_put() in the
    if(is_badblock(...)) error path in raid5_read_one_chunk().
    
    The error path was moved ahead of bio_alloc_clone() in c82aa1b7
    ("md/raid5: move checking badblock before clone bio in
    raid5_read_one_chunk"). The previous code checked and freed align_bio
    which required a bio_put. After the move that is no longer needed as
    raid_bio is returned to the control of the common io path which
    performs its own endio resulting in a double free on bad device blocks.
    
    Fixes: c82aa1b7 ("md/raid5: move checking badblock before clone bio in raid5_read_one_chunk")
    Signed-off-by: default avatarDavid Sloan <david.sloan@eideticom.com>
    Signed-off-by: default avatarLogan Gunthorpe <logang@deltatee.com>
    Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
    Acked-by: default avatarGuoqing Jiang <Guoqing.jiang@linux.dev>
    Signed-off-by: default avatarSong Liu <song@kernel.org>
    c66a6f41
raid5.c 255 KB