From: Josef Bacik <jbacik@redhat.com>
Subject: [RHEL5.1 PATCH] XEN: keep xen from allocating with GFP_KERNEL in 	an interrupt context
Date: Wed, 5 Sep 2007 15:32:47 -0400
Bugzilla: 279141
Message-Id: <20070905193246.GA21707@dhcp-243-37.rdu.redhat.com>
Changelog: [XEN] ia64: allocating with GFP_KERNEL in interrupt context fix


Hello,

This is in reference to bz 279141, which an exception is being filed for.  I'm
posting this now to get it out here and reviewed.  HP while running cert tests
ran into a panic, with a few BUG messages before the panic complaining about
being scheduled while atomic.  Come to find out the box was trying to schedule
from an interrupt context.  Under memory pressure we'd try to flush stuff out,
do an io_schedule() and then boom, problems.  This patch fixes it so when we
call xencomm_create from ia64_sal_get_state_info (which can be called during an
interrupt) we call it with GFP_ATOMIC instead of GFP_KERNEL.  We were able to
reproduce the problem inhouse, and with the patch are no longer able to
reproduce.  The customer will be testing this as well to double check.  Thank
you,

Josef

--- linux-2.6.18.x86_64/include/asm-ia64/sal.h.josef	2007-08-30 15:28:47.000000000 -0400
+++ linux-2.6.18.x86_64/include/asm-ia64/sal.h	2007-08-30 15:28:56.000000000 -0400
@@ -703,7 +703,7 @@ ia64_sal_get_state_info (u64 sal_info_ty
 
 		if (xencomm_create(sal_info,
 		                   ia64_sal_get_state_info_size(sal_info_type),
-		                   &desc, GFP_KERNEL))
+		                   &desc, GFP_ATOMIC))
 			return 0;
 
 		SAL_CALL_REENTRANT(isrv, SAL_GET_STATE_INFO, sal_info_type, 0,