The patch titled
fix Data Acess error in dup_fd
has been added to the -mm tree. Its filename is
fix-data-acess-error-in-dup_fd.patch
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: fix Data Acess error in dup_fd
From: Sharyathi Nagesh <sharyath@xxxxxxxxxx>
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@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
kernel/fork.c | 1 +
1 file changed, 1 insertion(+)
diff -puN kernel/fork.c~fix-data-acess-error-in-dup_fd kernel/fork.c
--- a/kernel/fork.c~fix-data-acess-error-in-dup_fd
+++ a/kernel/fork.c
@@ -687,6 +687,7 @@ static struct files_struct *dup_fd(struc
* the latest pointer.
*/
spin_lock(&oldf->file_lock);
+ open_files = count_open_files(old_fdt);
old_fdt = files_fdtable(oldf);
}
_
Patches currently in -mm which might be from sharyath@xxxxxxxxxx are
fix-data-acess-error-in-dup_fd.patch
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