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From: Michal Hocko <mhocko@kernel.org>
To: <linux-mm@kvack.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Oscar Salvador <OSalvador@suse.com>, Baoquan He <bhe@redhat.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Michal Hocko <mhocko@suse.com>
Subject: [RFC PATCH 4/5] mm, memory_hotplug: print reason for the offlining failure
Date: Wed,  7 Nov 2018 11:18:29 +0100	[thread overview]
Message-ID: <20181107101830.17405-5-mhocko@kernel.org> (raw)
In-Reply-To: <20181107101830.17405-1-mhocko@kernel.org>

From: Michal Hocko <mhocko@suse.com>

The memory offlining failure reporting is inconsistent and insufficient.
Some error paths simply do not report the failure to the log at all.
When we do report there are no details about the reason of the failure
and there are several of them which makes memory offlining failures
hard to debug.

Make sure that the
	memory offlining [mem %#010llx-%#010llx] failed
message is printed for all failures and also provide a short textual
reason for the failure e.g.

[ 1984.506184] rac1 kernel: memory offlining [mem 0x82600000000-0x8267fffffff] failed due to signal backoff

this tells us that the offlining has failed because of a signal pending
aka user intervention.

Signed-off-by: Michal Hocko <mhocko@suse.com>
---
 mm/memory_hotplug.c | 34 +++++++++++++++++++++++-----------
 1 file changed, 23 insertions(+), 11 deletions(-)

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index a92b1b8f6218..1badac89c58e 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1553,6 +1553,7 @@ static int __ref __offline_pages(unsigned long start_pfn,
 	unsigned long valid_start, valid_end;
 	struct zone *zone;
 	struct memory_notify arg;
+	char *reason;
 
 	mem_hotplug_begin();
 
@@ -1561,7 +1562,9 @@ static int __ref __offline_pages(unsigned long start_pfn,
 	if (!test_pages_in_a_zone(start_pfn, end_pfn, &valid_start,
 				  &valid_end)) {
 		mem_hotplug_done();
-		return -EINVAL;
+		ret = -EINVAL;
+		reason = "multizone range";
+		goto failed_removal;
 	}
 
 	zone = page_zone(pfn_to_page(valid_start));
@@ -1573,7 +1576,8 @@ static int __ref __offline_pages(unsigned long start_pfn,
 				       MIGRATE_MOVABLE, true);
 	if (ret) {
 		mem_hotplug_done();
-		return ret;
+		reason = "failed to isolate range";
+		goto failed_removal
 	}
 
 	arg.start_pfn = start_pfn;
@@ -1582,15 +1586,19 @@ static int __ref __offline_pages(unsigned long start_pfn,
 
 	ret = memory_notify(MEM_GOING_OFFLINE, &arg);
 	ret = notifier_to_errno(ret);
-	if (ret)
-		goto failed_removal;
+	if (ret) {
+		reason = "notifiers failure";
+		goto failed_removal_isolated;
+	}
 
 	pfn = start_pfn;
 repeat:
 	/* start memory hot removal */
 	ret = -EINTR;
-	if (signal_pending(current))
-		goto failed_removal;
+	if (signal_pending(current)) {
+		reason = "signal backoff";
+		goto failed_removal_isolated;
+	}
 
 	cond_resched();
 	lru_add_drain_all();
@@ -1607,8 +1615,10 @@ static int __ref __offline_pages(unsigned long start_pfn,
 	 * actually in order to make hugetlbfs's object counting consistent.
 	 */
 	ret = dissolve_free_huge_pages(start_pfn, end_pfn);
-	if (ret)
-		goto failed_removal;
+	if (ret) {
+		reason = "fails to disolve hugetlb pages";
+		goto failed_removal_isolated;
+	}
 	/* check again */
 	offlined_pages = check_pages_isolated(start_pfn, end_pfn);
 	if (offlined_pages < 0)
@@ -1648,13 +1658,15 @@ static int __ref __offline_pages(unsigned long start_pfn,
 	mem_hotplug_done();
 	return 0;
 
+failed_removal_isolated:
+	undo_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
 failed_removal:
-	pr_debug("memory offlining [mem %#010llx-%#010llx] failed\n",
+	pr_debug("memory offlining [mem %#010llx-%#010llx] failed due to %s\n",
 		 (unsigned long long) start_pfn << PAGE_SHIFT,
-		 ((unsigned long long) end_pfn << PAGE_SHIFT) - 1);
+		 ((unsigned long long) end_pfn << PAGE_SHIFT) - 1,
+		 reason);
 	memory_notify(MEM_CANCEL_OFFLINE, &arg);
 	/* pushback to free area */
-	undo_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
 	mem_hotplug_done();
 	return ret;
 }
-- 
2.19.1


WARNING: multiple messages have this Message-ID
From: Michal Hocko <mhocko@kernel.org>
To: linux-mm@kvack.org
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Oscar Salvador <OSalvador@suse.com>, Baoquan He <bhe@redhat.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Michal Hocko <mhocko@suse.com>
Subject: [RFC PATCH 4/5] mm, memory_hotplug: print reason for the offlining failure
Date: Wed,  7 Nov 2018 11:18:29 +0100	[thread overview]
Message-ID: <20181107101830.17405-5-mhocko@kernel.org> (raw)
In-Reply-To: <20181107101830.17405-1-mhocko@kernel.org>

From: Michal Hocko <mhocko@suse.com>

The memory offlining failure reporting is inconsistent and insufficient.
Some error paths simply do not report the failure to the log at all.
When we do report there are no details about the reason of the failure
and there are several of them which makes memory offlining failures
hard to debug.

Make sure that the
	memory offlining [mem %#010llx-%#010llx] failed
message is printed for all failures and also provide a short textual
reason for the failure e.g.

[ 1984.506184] rac1 kernel: memory offlining [mem 0x82600000000-0x8267fffffff] failed due to signal backoff

this tells us that the offlining has failed because of a signal pending
aka user intervention.

Signed-off-by: Michal Hocko <mhocko@suse.com>
---
 mm/memory_hotplug.c | 34 +++++++++++++++++++++++-----------
 1 file changed, 23 insertions(+), 11 deletions(-)

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index a92b1b8f6218..1badac89c58e 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1553,6 +1553,7 @@ static int __ref __offline_pages(unsigned long start_pfn,
 	unsigned long valid_start, valid_end;
 	struct zone *zone;
 	struct memory_notify arg;
+	char *reason;
 
 	mem_hotplug_begin();
 
@@ -1561,7 +1562,9 @@ static int __ref __offline_pages(unsigned long start_pfn,
 	if (!test_pages_in_a_zone(start_pfn, end_pfn, &valid_start,
 				  &valid_end)) {
 		mem_hotplug_done();
-		return -EINVAL;
+		ret = -EINVAL;
+		reason = "multizone range";
+		goto failed_removal;
 	}
 
 	zone = page_zone(pfn_to_page(valid_start));
@@ -1573,7 +1576,8 @@ static int __ref __offline_pages(unsigned long start_pfn,
 				       MIGRATE_MOVABLE, true);
 	if (ret) {
 		mem_hotplug_done();
-		return ret;
+		reason = "failed to isolate range";
+		goto failed_removal
 	}
 
 	arg.start_pfn = start_pfn;
@@ -1582,15 +1586,19 @@ static int __ref __offline_pages(unsigned long start_pfn,
 
 	ret = memory_notify(MEM_GOING_OFFLINE, &arg);
 	ret = notifier_to_errno(ret);
-	if (ret)
-		goto failed_removal;
+	if (ret) {
+		reason = "notifiers failure";
+		goto failed_removal_isolated;
+	}
 
 	pfn = start_pfn;
 repeat:
 	/* start memory hot removal */
 	ret = -EINTR;
-	if (signal_pending(current))
-		goto failed_removal;
+	if (signal_pending(current)) {
+		reason = "signal backoff";
+		goto failed_removal_isolated;
+	}
 
 	cond_resched();
 	lru_add_drain_all();
@@ -1607,8 +1615,10 @@ static int __ref __offline_pages(unsigned long start_pfn,
 	 * actually in order to make hugetlbfs's object counting consistent.
 	 */
 	ret = dissolve_free_huge_pages(start_pfn, end_pfn);
-	if (ret)
-		goto failed_removal;
+	if (ret) {
+		reason = "fails to disolve hugetlb pages";
+		goto failed_removal_isolated;
+	}
 	/* check again */
 	offlined_pages = check_pages_isolated(start_pfn, end_pfn);
 	if (offlined_pages < 0)
@@ -1648,13 +1658,15 @@ static int __ref __offline_pages(unsigned long start_pfn,
 	mem_hotplug_done();
 	return 0;
 
+failed_removal_isolated:
+	undo_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
 failed_removal:
-	pr_debug("memory offlining [mem %#010llx-%#010llx] failed\n",
+	pr_debug("memory offlining [mem %#010llx-%#010llx] failed due to %s\n",
 		 (unsigned long long) start_pfn << PAGE_SHIFT,
-		 ((unsigned long long) end_pfn << PAGE_SHIFT) - 1);
+		 ((unsigned long long) end_pfn << PAGE_SHIFT) - 1,
+		 reason);
 	memory_notify(MEM_CANCEL_OFFLINE, &arg);
 	/* pushback to free area */
-	undo_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
 	mem_hotplug_done();
 	return ret;
 }
-- 
2.19.1

  parent reply	other threads:[~2018-11-07 10:18 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-07 10:18 [RFC PATCH 0/5] mm, memory_hotplug: improve memory offlining failures debugging Michal Hocko
2018-11-07 10:18 ` Michal Hocko
2018-11-07 10:18 ` [RFC PATCH 1/5] mm: print more information about mapping in __dump_page Michal Hocko
2018-11-07 10:18   ` Michal Hocko
2018-11-24  0:04   ` Andrew Morton
2018-11-24  0:04     ` Andrew Morton
2018-11-25  8:10     ` Michal Hocko
2018-11-07 10:18 ` [RFC PATCH 2/5] mm: lower the printk loglevel for __dump_page messages Michal Hocko
2018-11-07 10:18   ` Michal Hocko
2018-11-16  0:56   ` Baoquan He
2018-12-12 14:25   ` Michal Hocko
2018-12-12 14:34     ` Michal Hocko
2018-11-07 10:18 ` [RFC PATCH 3/5] mm, memory_hotplug: drop pointless block alignment checks from __offline_pages Michal Hocko
2018-11-07 10:18   ` Michal Hocko
2018-11-07 10:18 ` Michal Hocko [this message]
2018-11-07 10:18   ` [RFC PATCH 4/5] mm, memory_hotplug: print reason for the offlining failure Michal Hocko
2018-11-07 22:04   ` Andrew Morton
2018-11-07 22:04     ` Andrew Morton
2018-11-08  8:01     ` Michal Hocko
2018-11-13  8:02     ` Michal Hocko
2018-11-08  6:23   ` Anshuman Khandual
2018-11-08  7:59     ` Michal Hocko
2018-11-07 10:18 ` [RFC PATCH 5/5] mm, memory_hotplug: be more verbose for memory offline failures Michal Hocko
2018-11-07 10:18   ` Michal Hocko
2018-11-08  7:16   ` Anshuman Khandual
2018-11-08  8:12     ` Michal Hocko
2018-11-08  8:19       ` Anshuman Khandual
2018-11-13  8:03       ` Michal Hocko
2018-11-16  0:07   ` Andrew Morton
2018-11-16  0:07     ` Andrew Morton
2018-11-16  7:21     ` Michal Hocko
2018-11-16  7:21       ` Michal Hocko

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