[lkml]   [2007]   [Aug]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
Patch in this message
Subjecti386 doublefault handler is broken with CONFIG_DEBUG_SPINLOCK
The new percpu code has apparently broken the doublefault handler
when CONFIG_DEBUG_SPINLOCK is set. Doublefault is handled by
a hardware task, making the check

SPIN_BUG_ON(lock->owner == current, lock, "recursion");

fault because it uses the FS register to access the percpu data
for current, and that register is zero in the new TSS. (The trace
I saw was on 2.6.20 where it was GS, but it looks like this will
still happen with FS on 2.6.22.)

Initializing FS in the doublefault_tss should fix it.

Signed-off-by: Chuck Ebbert <>


NOTE: not even compile tested.

arch/i386/kernel/doublefault.c | 1 +
1 file changed, 1 insertion(+)

--- linux-2.6.22.noarch.orig/arch/i386/kernel/doublefault.c
+++ linux-2.6.22.noarch/arch/i386/kernel/doublefault.c
@@ -63,6 +63,7 @@ struct tss_struct doublefault_tss __cach
.cs = __KERNEL_CS,
.ss = __KERNEL_DS,
.ds = __USER_DS,
+ .fs = __KERNEL_PERCPU,

.__cr3 = __pa(swapper_pg_dir)
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at
 \ /
  Last update: 2007-08-09 18:53    [W:0.053 / U:0.320 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site