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Date: Sun, 6 Dec 2009 11:46:36 +0800
From: Wu Fengguang <fengguang.wu@...el.com>
To: Alex Chiang <achiang@...com>
Cc: "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
"Li, Haicheng" <haicheng.li@...el.com>,
Randy Dunlap <randy.dunlap@...cle.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-mm@...ck.org" <linux-mm@...ck.org>,
Andi Kleen <andi@...stfloor.org>, Ingo Molnar <mingo@...e.hu>,
Christoph Lameter <cl@...ux-foundation.org>,
Rik van Riel <riel@...hat.com>, Mel Gorman <mel@....ul.ie>,
KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
Subject: [RFC] print symbolic page flag names in bad_page()
Hi Alex,
On Sat, Dec 05, 2009 at 05:29:48AM +0800, Alex Chiang wrote:
[...]
> Teach page-types the -k mode, which parses and describes the bits in
> the internal kernel order:
>
> # ./Documentation/vm/page-types -k 0x4000
> 0x0000000000004000 ______________H_________ compound_head
[...]
> The implication is that attempting to use page-types -k on a kernel
> with different CONFIG_* settings may lead to surprising and misleading
> results. To retain sanity, always use the page-types built out of the
> kernel tree you are actually testing.
This is useful feature, however not as convenient if the kernel can
print its page flag names directly :)
(especially when the dmesg comes from some end user)
So how about this patch?
---
mm: introduce dump_page()
- introduce dump_page() to print the page info for debugging some error condition.
- print an extra field: the symbolic names of page->flags
- convert three mm users: bad_page(), print_bad_pte() and memory offline failure.
Signed-off-by: Wu Fengguang <fengguang.wu@...el.com>
---
mm/internal.h | 2 +
mm/memory.c | 8 +---
mm/memory_hotplug.c | 6 +--
mm/page_alloc.c | 75 +++++++++++++++++++++++++++++++++++++++---
4 files changed, 78 insertions(+), 13 deletions(-)
--- linux-mm.orig/mm/page_alloc.c 2009-12-06 10:11:08.000000000 +0800
+++ linux-mm/mm/page_alloc.c 2009-12-06 11:22:58.000000000 +0800
@@ -48,6 +48,7 @@
#include <linux/page_cgroup.h>
#include <linux/debugobjects.h>
#include <linux/kmemleak.h>
+#include <linux/kernel-page-flags.h>
#include <trace/events/kmem.h>
#include <asm/tlbflush.h>
@@ -262,10 +263,7 @@ static void bad_page(struct page *page)
printk(KERN_ALERT "BUG: Bad page state in process %s pfn:%05lx\n",
current->comm, page_to_pfn(page));
- printk(KERN_ALERT
- "page:%p flags:%p count:%d mapcount:%d mapping:%p index:%lx\n",
- page, (void *)page->flags, page_count(page),
- page_mapcount(page), page->mapping, page->index);
+ dump_page(page);
dump_stack();
out:
@@ -5106,3 +5104,72 @@ bool is_free_buddy_page(struct page *pag
return order < MAX_ORDER;
}
#endif
+
+static char *page_flag_names[] = {
+ [KPF_LOCKED] = "L:locked",
+ [KPF_ERROR] = "E:error",
+ [KPF_REFERENCED] = "R:referenced",
+ [KPF_UPTODATE] = "U:uptodate",
+ [KPF_DIRTY] = "D:dirty",
+ [KPF_LRU] = "l:lru",
+ [KPF_ACTIVE] = "A:active",
+ [KPF_SLAB] = "S:slab",
+ [KPF_WRITEBACK] = "W:writeback",
+ [KPF_RECLAIM] = "I:reclaim",
+ [KPF_BUDDY] = "B:buddy",
+
+ [KPF_MMAP] = "M:mmap",
+ [KPF_ANON] = "a:anonymous",
+ [KPF_SWAPCACHE] = "s:swapcache",
+ [KPF_SWAPBACKED] = "b:swapbacked",
+ [KPF_COMPOUND_HEAD] = "H:compound_head",
+ [KPF_COMPOUND_TAIL] = "T:compound_tail",
+ [KPF_HUGE] = "G:huge",
+ [KPF_UNEVICTABLE] = "u:unevictable",
+ [KPF_HWPOISON] = "X:hwpoison",
+ [KPF_NOPAGE] = "n:nopage",
+ [KPF_KSM] = "V:shared",
+
+ [KPF_RESERVED] = "r:reserved",
+ [KPF_MLOCKED] = "m:mlocked",
+ [KPF_MAPPEDTODISK] = "d:mappedtodisk",
+ [KPF_PRIVATE] = "P:private",
+ [KPF_PRIVATE_2] = "p:private_2",
+ [KPF_OWNER_PRIVATE] = "O:owner_private",
+ [KPF_ARCH] = "h:arch",
+ [KPF_UNCACHED] = "c:uncached",
+};
+
+static char *page_flags_longname(struct page *page, char *buf, int buflen)
+{
+ int i, n;
+ u64 flags;
+
+ flags = stable_page_flags(page);
+
+ for (i = 0, n = 0; i < ARRAY_SIZE(page_flag_names); i++) {
+ if (!page_flag_names[i])
+ continue;
+ if ((flags >> i) & 1)
+ n += snprintf(buf + n, buflen - n, "%s,",
+ page_flag_names[i] + 2);
+ }
+ if (n)
+ n--;
+ buf[n] = '\0';
+
+ return buf;
+}
+
+void dump_page(struct page *page)
+{
+ char buf[1024];
+
+ printk(KERN_ALERT
+ "page:%p flags:%p(%s) count:%d mapcount:%d mapping:%p index:%lx\n",
+ page, (void *)page->flags,
+ page_flags_longname(page, buf, sizeof(buf)),
+ page_count(page), page_mapcount(page),
+ page->mapping, page->index);
+}
+EXPORT_SYMBOL(dump_page);
--- linux-mm.orig/mm/memory.c 2009-12-06 10:37:47.000000000 +0800
+++ linux-mm/mm/memory.c 2009-12-06 10:57:25.000000000 +0800
@@ -430,12 +430,8 @@ static void print_bad_pte(struct vm_area
"BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n",
current->comm,
(long long)pte_val(pte), (long long)pmd_val(*pmd));
- if (page) {
- printk(KERN_ALERT
- "page:%p flags:%p count:%d mapcount:%d mapping:%p index:%lx\n",
- page, (void *)page->flags, page_count(page),
- page_mapcount(page), page->mapping, page->index);
- }
+ if (page)
+ dump_page(page);
printk(KERN_ALERT
"addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n",
(void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
--- linux-mm.orig/mm/internal.h 2009-12-06 10:47:37.000000000 +0800
+++ linux-mm/mm/internal.h 2009-12-06 11:03:53.000000000 +0800
@@ -264,6 +264,8 @@ int __get_user_pages(struct task_struct
#define ZONE_RECLAIM_SUCCESS 1
#endif
+void dump_page(struct page *page);
+
extern int hwpoison_filter(struct page *p);
extern u32 hwpoison_filter_dev_major;
--- linux-mm.orig/mm/memory_hotplug.c 2009-12-06 11:01:20.000000000 +0800
+++ linux-mm/mm/memory_hotplug.c 2009-12-06 11:01:23.000000000 +0800
@@ -678,9 +678,9 @@ do_migrate_range(unsigned long start_pfn
if (page_count(page))
not_managed++;
#ifdef CONFIG_DEBUG_VM
- printk(KERN_INFO "removing from LRU failed"
- " %lx/%d/%lx\n",
- pfn, page_count(page), page->flags);
+ printk(KERN_INFO "removing pfn %lx from LRU failed\n",
+ pfn);
+ dump_page(page);
#endif
}
}
--
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