Commit 0130b0b3 authored by Sharyathi Nagesh's avatar Sharyathi Nagesh Committed by Linus Torvalds
Browse files

[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

Cc: Vadim Lobanov <>
Cc: <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent 5fd934a9
......@@ -687,6 +687,7 @@ static struct files_struct *dup_fd(struct files_struct *oldf, int *errorp)
* the latest pointer.
open_files = count_open_files(old_fdt);
old_fdt = files_fdtable(oldf);
Markdown is supported
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment