The patch titled
Subject: mm,hwpoison: check mm when killing accessing process
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
mmhwpoison-check-mm-when-killing-accessing-process.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mmhwpoison-check-mm-when-killing-accessing-process.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Shuai Xue <xueshuai@xxxxxxxxxxxxxxxxx>
Subject: mm,hwpoison: check mm when killing accessing process
Date: Wed, 14 Sep 2022 14:49:35 +0800
The GHES code calls memory_failure_queue() from IRQ context to queue work
into workqueue and schedule it on the current CPU. Then the work is
processed in memory_failure_work_func() by kworker and calls
memory_failure().
When a page is already poisoned, commit a3f5d80ea401 ("mm,hwpoison: send
SIGBUS with error virutal address") make memory_failure() call
kill_accessing_process() that:
- holds mmap locking of current->mm
- does pagetable walk to find the error virtual address
- and sends SIGBUS to the current process with error info.
However, the mm of kworker is not valid, resulting in a null-pointer
dereference. So check mm when killing the accessing process.
Link: https://lkml.kernel.org/r/20220914064935.7851-1-xueshuai@xxxxxxxxxxxxxxxxx
Fixes: a3f5d80ea401 ("mm,hwpoison: send SIGBUS with error virutal address")
Signed-off-by: Shuai Xue <xueshuai@xxxxxxxxxxxxxxxxx>
Cc: Huang Ying <ying.huang@xxxxxxxxx>
Cc: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Cc: Bixuan Cui <cuibixuan@xxxxxxxxxxxxxxxxx>
Cc: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Cc: Naoya Horiguchi <naoya.horiguchi@xxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memory-failure.c | 4 ++++
1 file changed, 4 insertions(+)
--- a/mm/memory-failure.c~mmhwpoison-check-mm-when-killing-accessing-process
+++ a/mm/memory-failure.c
@@ -745,6 +745,9 @@ static int kill_accessing_process(struct
};
priv.tk.tsk = p;
+ if (!p->mm)
+ return -EFAULT;
+
mmap_read_lock(p->mm);
ret = walk_page_range(p->mm, 0, TASK_SIZE, &hwp_walk_ops,
(void *)&priv);
@@ -753,6 +756,7 @@ static int kill_accessing_process(struct
else
ret = 0;
mmap_read_unlock(p->mm);
+
return ret > 0 ? -EHWPOISON : -EFAULT;
}
_
Patches currently in -mm which might be from xueshuai@xxxxxxxxxxxxxxxxx are
mmhwpoison-check-mm-when-killing-accessing-process.patch
