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Subject[PATCH v1] mm: hwpoison: ratelimit messages from unpoison_memory()
Date
Currently kernel prints out results of every single unpoison event, which is
not necessary because unpoison is purely a testing feature and testers can get
little or no information from lots of lines of unpoison log storm. So this
patch ratelimits printk in unpoison_memory().

This patch introduces a file local ratelimit_state, which adds 64 bytes to
memory-failure.o. If we apply pr_info_ratelimited() for 8 callsite below, 256
bytes is added, so it's a win.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
---
mm/memory-failure.c | 34 +++++++++++++++++++++++++---------
1 file changed, 25 insertions(+), 9 deletions(-)

diff --git v4.3-rc1/mm/memory-failure.c v4.3-rc1_patched/mm/memory-failure.c
index 95882692e747..16a0ec385320 100644
--- v4.3-rc1/mm/memory-failure.c
+++ v4.3-rc1_patched/mm/memory-failure.c
@@ -56,6 +56,7 @@
#include <linux/memory_hotplug.h>
#include <linux/mm_inline.h>
#include <linux/kfifo.h>
+#include <linux/ratelimit.h>
#include "internal.h"
#include "ras/ras_event.h"

@@ -1403,6 +1404,12 @@ static int __init memory_failure_init(void)
}
core_initcall(memory_failure_init);

+#define unpoison_pr_info(fmt, pfn, rs) \
+({ \
+ if (__ratelimit(rs)) \
+ pr_info(fmt, pfn); \
+})
+
/**
* unpoison_memory - Unpoison a previously poisoned page
* @pfn: Page number of the to be unpoisoned page
@@ -1421,6 +1428,8 @@ int unpoison_memory(unsigned long pfn)
struct page *p;
int freeit = 0;
unsigned int nr_pages;
+ static DEFINE_RATELIMIT_STATE(unpoison_rs, DEFAULT_RATELIMIT_INTERVAL,
+ DEFAULT_RATELIMIT_BURST);

if (!pfn_valid(pfn))
return -ENXIO;
@@ -1429,23 +1438,26 @@ int unpoison_memory(unsigned long pfn)
page = compound_head(p);

if (!PageHWPoison(p)) {
- pr_info("MCE: Page was already unpoisoned %#lx\n", pfn);
+ unpoison_pr_info("MCE: Page was already unpoisoned %#lx\n",
+ pfn, &unpoison_rs);
return 0;
}

if (page_count(page) > 1) {
- pr_info("MCE: Someone grabs the hwpoison page %#lx\n", pfn);
+ unpoison_pr_info("MCE: Someone grabs the hwpoison page %#lx\n",
+ pfn, &unpoison_rs);
return 0;
}

if (page_mapped(page)) {
- pr_info("MCE: Someone maps the hwpoison page %#lx\n", pfn);
+ unpoison_pr_info("MCE: Someone maps the hwpoison page %#lx\n",
+ pfn, &unpoison_rs);
return 0;
}

if (page_mapping(page)) {
- pr_info("MCE: the hwpoison page has non-NULL mapping %#lx\n",
- pfn);
+ unpoison_pr_info("MCE: the hwpoison page has non-NULL mapping %#lx\n",
+ pfn, &unpoison_rs);
return 0;
}

@@ -1455,7 +1467,8 @@ int unpoison_memory(unsigned long pfn)
* In such case, we yield to memory_failure() and make unpoison fail.
*/
if (!PageHuge(page) && PageTransHuge(page)) {
- pr_info("MCE: Memory failure is now running on %#lx\n", pfn);
+ unpoison_pr_info("MCE: Memory failure is now running on %#lx\n",
+ pfn, &unpoison_rs);
return 0;
}

@@ -1469,12 +1482,14 @@ int unpoison_memory(unsigned long pfn)
* to the end.
*/
if (PageHuge(page)) {
- pr_info("MCE: Memory failure is now running on free hugepage %#lx\n", pfn);
+ unpoison_pr_info("MCE: Memory failure is now running on free hugepage %#lx\n",
+ pfn, &unpoison_rs);
return 0;
}
if (TestClearPageHWPoison(p))
num_poisoned_pages_dec();
- pr_info("MCE: Software-unpoisoned free page %#lx\n", pfn);
+ unpoison_pr_info("MCE: Software-unpoisoned free page %#lx\n",
+ pfn, &unpoison_rs);
return 0;
}

@@ -1486,7 +1501,8 @@ int unpoison_memory(unsigned long pfn)
* the free buddy page pool.
*/
if (TestClearPageHWPoison(page)) {
- pr_info("MCE: Software-unpoisoned page %#lx\n", pfn);
+ unpoison_pr_info("MCE: Software-unpoisoned page %#lx\n",
+ pfn, &unpoison_rs);
num_poisoned_pages_sub(nr_pages);
freeit = 1;
if (PageHuge(page))
--
2.4.3

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