[PATCH 1/1] Elevator init fixes
From: Zachary Amsden
Date: Mon Nov 07 2005 - 19:04:27 EST
I got a panic in the elevator code, backtrace :
Unable to handle kernel NULL pointer dereference at virtual address 00000060
..
EIP is at elevator_put+0x0/0x30 (null elevator_type passed)
..
elevator_init+0x38
blk_init_queu_node+0xc9
floppy_init+0xdb
do_initcalls+0x23
init+0x10a
init+0x0
Clearly if the kmalloc here fails, e->elevator_type is not yet set; this
appears to be the correct fix, but I think I probably hit the second case
due to a race condition. Someone more familiar with the elevator code
should look at this more closely until I can determine if I can reproduce.
Signed-off-by: Zachary Amsden <zach@xxxxxxxxxx>
Index: linux-2.6.14-zach-work/drivers/block/elevator.c
===================================================================
--- linux-2.6.14-zach-work.orig/drivers/block/elevator.c 2005-11-07 09:41:11.000000000 -0800
+++ linux-2.6.14-zach-work/drivers/block/elevator.c 2005-11-07 15:57:10.000000000 -0800
@@ -190,14 +190,14 @@ int elevator_init(request_queue_t *q, ch
eq = kmalloc(sizeof(struct elevator_queue), GFP_KERNEL);
if (!eq) {
- elevator_put(e->elevator_type);
+ elevator_put(e);
return -ENOMEM;
}
ret = elevator_attach(q, e, eq);
if (ret) {
kfree(eq);
- elevator_put(e->elevator_type);
+ elevator_put(e);
}
return ret;
-
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