From: Kei Tokunaga <ktokunag@redhat.com>
Subject: [RHEL5 PATCH] Noisy stack trace is displayed by memory hotplug on  memory busy system
Date: Tue, 07 Nov 2006 15:39:37 -0500
Bugzilla: 213066
Message-Id: <4550EF09.70402@redhat.com>
Changelog: Noisy stack trace by memory hotplug on memory busy system


BZ213066
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=213066

This patch suppresses unnecessary stack trace displayed in
the event of memory hotplug on memory busy system.

When memory hot-add is executed, kernel tries to allocate
new pages for mmap of new memories by calling alloc_pages()
in __kmalloc_section_memmap().  Its order of memmap_size
can be big enough (It becomes 8 in ia64) to cause a page
allocation failure and stack trace is displayed in the
failure case.  But in that case, __kmalloc_section_memmap()
secondarily calls vmalloc() to allocate the memmap.  So,
the stack trace is unnecessary at that point.  This patch
fix the issue by adding __GFP_NOWARN to the flag when calling
alloc_pages().

Attached is for the latest CVS kernel (2.6.18-1.2746.el5),
which is a small one-line fix.   The fix is already in
upstream.

We have put it though the paces on our boxes and verified
that it works all right.

Thanks,
Kei

---

 linux-2.6.18-1.2746.el5-kei/mm/sparse.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff -puN mm/sparse.c~bz213066-suppress_unnecessary_stack_trace mm/sparse.c
--- linux-2.6.18-1.2746.el5/mm/sparse.c~bz213066-suppress_unnecessary_stack_trace	2006-11-07 14:46:42.000000000 -0500
+++ linux-2.6.18-1.2746.el5-kei/mm/sparse.c	2006-11-07 14:46:42.000000000 -0500
@@ -211,7 +211,7 @@ static struct page *__kmalloc_section_me
 	struct page *page, *ret;
 	unsigned long memmap_size = sizeof(struct page) * nr_pages;
 
-	page = alloc_pages(GFP_KERNEL, get_order(memmap_size));
+	page = alloc_pages(GFP_KERNEL|__GFP_NOWARN, get_order(memmap_size));
 	if (page)
 		goto got_map_page;
 

_