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author | Jeff Layton <jlayton@redhat.com> | 2012-07-11 13:09:36 (GMT) |
---|---|---|
committer | Steve French <smfrench@gmail.com> | 2012-07-17 04:57:14 (GMT) |
commit | 3cf003c08be785af4bee9ac05891a15bcbff856a (patch) | |
tree | f54e5a39dd782af881a4e5927225f2fd3a704889 /fs/cifs/readdir.c | |
parent | 3ae629d98bd5ed77585a878566f04f310adbc591 (diff) | |
download | linux-3cf003c08be785af4bee9ac05891a15bcbff856a.tar.xz |
cifs: when CONFIG_HIGHMEM is set, serialize the read/write kmaps
Jian found that when he ran fsx on a 32 bit arch with a large wsize the
process and one of the bdi writeback kthreads would sometimes deadlock
with a stack trace like this:
crash> bt
PID: 2789 TASK: f02edaa0 CPU: 3 COMMAND: "fsx"
#0 [eed63cbc] schedule at c083c5b3
#1 [eed63d80] kmap_high at c0500ec8
#2 [eed63db0] cifs_async_writev at f7fabcd7 [cifs]
#3 [eed63df0] cifs_writepages at f7fb7f5c [cifs]
#4 [eed63e50] do_writepages at c04f3e32
#5 [eed63e54] __filemap_fdatawrite_range at c04e152a
#6 [eed63ea4] filemap_fdatawrite at c04e1b3e
#7 [eed63eb4] cifs_file_aio_write at f7fa111a [cifs]
#8 [eed63ecc] do_sync_write at c052d202
#9 [eed63f74] vfs_write at c052d4ee
#10 [eed63f94] sys_write at c052df4c
#11 [eed63fb0] ia32_sysenter_target at c0409a98
EAX: 00000004 EBX: 00000003 ECX: abd73b73 EDX: 012a65c6
DS: 007b ESI: 012a65c6 ES: 007b EDI: 00000000
SS: 007b ESP: bf8db178 EBP: bf8db1f8 GS: 0033
CS: 0073 EIP: 40000424 ERR: 00000004 EFLAGS: 00000246
Each task would kmap part of its address array before getting stuck, but
not enough to actually issue the write.
This patch fixes this by serializing the marshal_iov operations for
async reads and writes. The idea here is to ensure that cifs
aggressively tries to populate a request before attempting to fulfill
another one. As soon as all of the pages are kmapped for a request, then
we can unlock and allow another one to proceed.
There's no need to do this serialization on non-CONFIG_HIGHMEM arches
however, so optimize all of this out when CONFIG_HIGHMEM isn't set.
Cc: <stable@vger.kernel.org>
Reported-by: Jian Li <jiali@redhat.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <smfrench@gmail.com>
Diffstat (limited to 'fs/cifs/readdir.c')
0 files changed, 0 insertions, 0 deletions