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| author | Sharyathi Nagesh <sharyath@in.ibm.com> | 2006-11-10 12:27:54 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-11-13 07:40:43 -0800 |
| commit | 0130b0b32ee53dc7add773fcea984f6a26ef1da3 (patch) | |
| tree | 2a4920ab222bf2cfa24e0b25522478120bd51afe /kernel/fork.c | |
| parent | 5fd934a9a1b72c718ad5c388fd2e0fd90486cbf3 (diff) | |
| download | lwn-0130b0b32ee53dc7add773fcea984f6a26ef1da3.tar.gz lwn-0130b0b32ee53dc7add773fcea984f6a26ef1da3.zip | |
[PATCH] fix Data Acess error in dup_fd
On running the Stress Test on machine for more than 72 hours following
error message was observed.
0:mon> e
cpu 0x0: Vector: 300 (Data Access) at [c00000007ce2f7f0]
pc: c000000000060d90: .dup_fd+0x240/0x39c
lr: c000000000060d6c: .dup_fd+0x21c/0x39c
sp: c00000007ce2fa70
msr: 800000000000b032
dar: ffffffff00000028
dsisr: 40000000
current = 0xc000000074950980
paca = 0xc000000000454500
pid = 27330, comm = bash
0:mon> t
[c00000007ce2fa70] c000000000060d28 .dup_fd+0x1d8/0x39c (unreliable)
[c00000007ce2fb30] c000000000060f48 .copy_files+0x5c/0x88
[c00000007ce2fbd0] c000000000061f5c .copy_process+0x574/0x1520
[c00000007ce2fcd0] c000000000062f88 .do_fork+0x80/0x1c4
[c00000007ce2fdc0] c000000000011790 .sys_clone+0x5c/0x74
[c00000007ce2fe30] c000000000008950 .ppc_clone+0x8/0xc
The problem is because of race window. When if(expand) block is executed in
dup_fd unlocking of oldf->file_lock give a window for fdtable in oldf to be
modified. So actual open_files in oldf may not match with open_files
variable.
Cc: Vadim Lobanov <vlobanov@speakeasy.net>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'kernel/fork.c')
| -rw-r--r-- | kernel/fork.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/kernel/fork.c b/kernel/fork.c index 3da978eec791..4b4eab2a3161 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -687,6 +687,7 @@ static struct files_struct *dup_fd(struct files_struct *oldf, int *errorp) * the latest pointer. */ spin_lock(&oldf->file_lock); + open_files = count_open_files(old_fdt); old_fdt = files_fdtable(oldf); } |