• Kees Cook's avatar
    pstore: pass allocated memory region back to caller · f6f82851
    Kees Cook authored
    The buf_lock cannot be held while populating the inodes, so make the backend
    pass forward an allocated and filled buffer instead. This solves the following
    backtrace. The effect is that "buf" is only ever used to notify the backends
    that something was written to it, and shouldn't be used in the read path.
    
    To replace the buf_lock during the read path, isolate the open/read/close
    loop with a separate mutex to maintain serialized access to the backend.
    
    Note that is is up to the pstore backend to cope if the (*write)() path is
    called in the middle of the read path.
    
    [   59.691019] BUG: sleeping function called from invalid context at .../mm/slub.c:847
    [   59.691019] in_atomic(): 0, irqs_disabled(): 1, pid: 1819, name: mount
    [   59.691019] Pid: 1819, comm: mount Not tainted 3.0.8 #1
    [   59.691019] Call Trace:
    [   59.691019]  [<810252d5>] __might_sleep+0xc3/0xca
    [   59.691019]  [<810a26e6>] kmem_cache_alloc+0x32/0xf3
    [   59.691019]  [<810b53ac>] ? __d_lookup_rcu+0x6f/0xf4
    [   59.691019]  [<810b68b1>] alloc_inode+0x2a/0x64
    [   59.691019]  [<810b6903>] new_inode+0x18/0x43
    [   59.691019]  [<81142447>] pstore_get_inode.isra.1+0x11/0x98
    [   59.691019]  [<81142623>] pstore_mkfile+0xae/0x26f
    [   59.691019]  [<810a2a66>] ? kmem_cache_free+0x19/0xb1
    [   59.691019]  [<8116c821>] ? ida_get_new_above+0x140/0x158
    [   59.691019]  [<811708ea>] ? __init_rwsem+0x1e/0x2c
    [   59.691019]  [<810b67e8>] ? inode_init_always+0x111/0x1b0
    [   59.691019]  [<8102127e>] ? should_resched+0xd/0x27
    [   59.691019]  [<8137977f>] ? _cond_resched+0xd/0x21
    [   59.691019]  [<81142abf>] pstore_get_records+0x52/0xa7
    [   59.691019]  [<8114254b>] pstore_fill_super+0x7d/0x91
    [   59.691019]  [<810a7ff5>] mount_single+0x46/0x82
    [   59.691019]  [<8114231a>] pstore_mount+0x15/0x17
    [   59.691019]  [<811424ce>] ? pstore_get_inode.isra.1+0x98/0x98
    [   59.691019]  [<810a8199>] mount_fs+0x5a/0x12d
    [   59.691019]  [<810b9174>] ? alloc_vfsmnt+0xa4/0x14a
    [   59.691019]  [<810b9474>] vfs_kern_mount+0x4f/0x7d
    [   59.691019]  [<810b9d7e>] do_kern_mount+0x34/0xb2
    [   59.691019]  [<810bb15f>] do_mount+0x5fc/0x64a
    [   59.691019]  [<810912fb>] ? strndup_user+0x2e/0x3f
    [   59.691019]  [<810bb3cb>] sys_mount+0x66/0x99
    [   59.691019]  [<8137b537>] sysenter_do_call+0x12/0x26
    Signed-off-by: default avatarKees Cook <keescook@chromium.org>
    Signed-off-by: default avatarTony Luck <tony.luck@intel.com>
    f6f82851
erst.c 28.4 KB