Skip to content
Commit 92715e28 authored by Ravikiran G Thirumalai's avatar Ravikiran G Thirumalai Committed by Andi Kleen
Browse files

[PATCH] x86: Fix boot hang due to nmi watchdog init code



2.6.19  stopped booting (or booted based on build/config) on our x86_64
systems due to a bug introduced in 2.6.19.  check_nmi_watchdog schedules an
IPI on all cpus to  busy wait on a flag, but fails to set the busywait
flag if NMI functionality is disabled.  This causes the secondary cpus
to spin in an endless loop, causing the kernel bootup to hang.
Depending upon the build, the  busywait flag got overwritten (stack variable)
and caused  the kernel to bootup on certain builds.  Following patch fixes
the bug by setting the busywait flag before returning from check_nmi_watchdog.
I guess using a stack variable is not good here as the calling function could
potentially return while the busy wait loop is still spinning on the flag.

AK: I redid the patch significantly to be cleaner

Signed-off-by: default avatarRavikiran Thirumalai <kiran@scalex86.org>
Signed-off-by: default avatarShai Fultheim <shai@scalex86.org>
Signed-off-by: default avatarAndi Kleen <ak@suse.de>
parent 16d279d2
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