New subject: [PATCH openEuler-1.0-LTS 2/5] arm64/ascend: Delete unused feature auto-tuning hugepage

16 Feb 2023

From: Liu Shixin liushixin2@huawei.com
hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I6AXGS
CVE: NA
--------------------------------
syzbot is reporting GFP_KERNEL allocation with oom_lock held when
reporting memcg OOM [1]. If this allocation triggers the global OOM
situation then the system can livelock because the GFP_KERNEL
allocation with oom_lock held cannot trigger the global OOM killer
because __alloc_pages_may_oom() fails to hold oom_lock.
The problem mentioned above has been fixed by patch[2]. The is the same
problem in memcg_memfs_info feature too. Refer to the patch[2], fix it by
removing the allocation from mem_cgroup_print_memfs_info() completely,
and pass static buffer when calling from memcg OOM path.
Link: https://syzkaller.appspot.com/bug?extid=2d2aeadc6ce1e1f11d45 [1]
Link: https://lkml.kernel.org/r/86afb39f-8c65-bec2-6cfc-c5e3cd600c0b@I-love.SAKURA... [2]
Fixes: 6b1d4d3a3713 ("mm/memcg_memfs_info: show files that having pages charged in mem_cgroup")
Signed-off-by: Liu Shixin liushixin2@huawei.com
Reviewed-by: Kefeng Wang wangkefeng.wang@huawei.com
Signed-off-by: Yongqiang Liu liuyongqiang13@huawei.com
---
 include/linux/memcg_memfs_info.h |  4 +++-
 mm/memcg_memfs_info.c            | 20 ++++++++++----------
 mm/memcontrol.c                  |  3 ++-
 3 files changed, 15 insertions(+), 12 deletions(-)

diff --git a/include/linux/memcg_memfs_info.h b/include/linux/memcg_memfs_info.h
index 658a91e22bd7..b5e3709baa9e 100644
--- a/include/linux/memcg_memfs_info.h
+++ b/include/linux/memcg_memfs_info.h
@@ -6,11 +6,13 @@
 #include <linux/seq_file.h>
#ifdef CONFIG_MEMCG_MEMFS_INFO
-void mem_cgroup_print_memfs_info(struct mem_cgroup *memcg, struct seq_file *m);
+void mem_cgroup_print_memfs_info(struct mem_cgroup *memcg, char *pathbuf,
+				 struct seq_file *m);
 int mem_cgroup_memfs_files_show(struct seq_file *m, void *v);
 void mem_cgroup_memfs_info_init(void);
 #else
 static inline void mem_cgroup_print_memfs_info(struct mem_cgroup *memcg,
+					       char *pathbuf,
    				       struct seq_file *m)
 {
 }
diff --git a/mm/memcg_memfs_info.c b/mm/memcg_memfs_info.c
index 346175026cae..632e03da673b 100644
--- a/mm/memcg_memfs_info.c
+++ b/mm/memcg_memfs_info.c
@@ -162,7 +162,8 @@ static void memfs_show_files_in_mem_cgroup(struct super_block *sb, void *data)
    mntput(pfc->vfsmnt);
 }
-void mem_cgroup_print_memfs_info(struct mem_cgroup *memcg, struct seq_file *m)
+void mem_cgroup_print_memfs_info(struct mem_cgroup *memcg, char *pathbuf,
+				 struct seq_file *m)
 {
    struct print_files_control pfc = {
    	.memcg = memcg,
@@ -170,17 +171,11 @@ void mem_cgroup_print_memfs_info(struct mem_cgroup *memcg, struct seq_file *m)
    	.max_print_files = memfs_max_print_files,
    	.size_threshold = memfs_size_threshold,
    };
-	char *pathbuf;
    int i;
if (!memfs_enable || !memcg)
    	return;
-	pathbuf = kmalloc(PATH_MAX, GFP_KERNEL);
-	if (!pathbuf) {
-		SEQ_printf(m, "Show memfs failed due to OOM\n");
-		return;
-	}
    pfc.pathbuf = pathbuf;
    pfc.pathbuf_size = PATH_MAX;
@@ -197,15 +192,20 @@ void mem_cgroup_print_memfs_info(struct mem_cgroup *memcg, struct seq_file *m)
    	SEQ_printf(m, "total files: %lu, total memory-size: %lukB\n",
    		   pfc.total_print_files, pfc.total_files_size >> 10);
    }
-
-	kfree(pfc.pathbuf);
 }
int mem_cgroup_memfs_files_show(struct seq_file *m, void *v)
 {
    struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
+	char *pathbuf;
-	mem_cgroup_print_memfs_info(memcg, m);
+	pathbuf = kmalloc(PATH_MAX, GFP_KERNEL);
+	if (!pathbuf) {
+		SEQ_printf(m, "Show memfs abort: failed to allocate memory\n");
+		return 0;
+	}
+	mem_cgroup_print_memfs_info(memcg, pathbuf, m);
+	kfree(pathbuf);
    return 0;
 }
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index bdc90e6fc082..fd40fef49e45 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1490,6 +1490,7 @@ void mem_cgroup_print_oom_meminfo(struct mem_cgroup *memcg)
 {
    struct mem_cgroup *iter;
    unsigned int i;
+	static char pathbuf[PATH_MAX];
pr_info("memory: usage %llukB, limit %llukB, failcnt %lu\n",
    	K((u64)page_counter_read(&memcg->memory)),
@@ -1522,7 +1523,7 @@ void mem_cgroup_print_oom_meminfo(struct mem_cgroup *memcg)
    	pr_cont("\n");
    }
-	mem_cgroup_print_memfs_info(memcg, NULL);
+	mem_cgroup_print_memfs_info(memcg, pathbuf, NULL);
 }
/*
-- 
2.25.1


    

[PATCH openEuler-1.0-LTS 1/5] mm/memcg_memfs_info: fix potential oom_lock recursion deadlock