[PATCH v5 1/2] mm/hwpoison: Avoid the impact of hwpoison_filter() return value on mce handler

[PATCH v5 1/2] mm/hwpoison: Avoid the impact of hwpoison_filter() return value on mce handler

[luofei]

When the hwpoison page meets the filter conditions, it should
not be regarded as successful memory_failure() processing for
mce handler, but should return a distinct value, otherwise
mce handler regards the error page has been identified and
isolated, which may lead to calling set_mce_nospec() to change
page attribute, etc.

Here memory_failure() return -EOPNOTSUPP to indicate that the
error event is filtered, mce handler should not take any action
for this situation and hwpoison injector should treat as correct.

Signed-off-by: luofei <luofei@unicloud.com>
---
 arch/x86/kernel/cpu/mce/core.c | 8 +++++---
 drivers/base/memory.c          | 2 ++
 mm/hwpoison-inject.c           | 3 ++-
 mm/madvise.c                   | 2 ++
 mm/memory-failure.c            | 9 +++++++--
 5 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
index 728f3b36ce2d..f4b56904db8a 100644
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -1332,10 +1332,12 @@ static void kill_me_maybe(struct callback_head *cb)
 
 	/*
 	 * -EHWPOISON from memory_failure() means that it already sent SIGBUS
-	 * to the current process with the proper error info, so no need to
-	 * send SIGBUS here again.
+	 * to the current process with the proper error info,
+	 * -EOPNOTSUPP means hwpoison_filter() filtered the error event,
+	 *
+	 * In both cases, no further processing is required.
 	 */
-	if (ret == -EHWPOISON)
+	if (ret == -EHWPOISON || ret == -EOPNOTSUPP)
 		return;
 
 	pr_err("Memory error not recovered");
diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index 365cd4a7f239..abf407e45467 100644
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -555,6 +555,8 @@ static ssize_t hard_offline_page_store(struct device *dev,
 		return -EINVAL;
 	pfn >>= PAGE_SHIFT;
 	ret = memory_failure(pfn, 0);
+	if (ret == -EOPNOTSUPP)
+		ret = 0;
 	return ret ? ret : count;
 }
 
diff --git a/mm/hwpoison-inject.c b/mm/hwpoison-inject.c
index aff4d27ec235..a1d6fc3c78b9 100644
--- a/mm/hwpoison-inject.c
+++ b/mm/hwpoison-inject.c
@@ -48,7 +48,8 @@ static int hwpoison_inject(void *data, u64 val)
 
 inject:
 	pr_info("Injecting memory failure at pfn %#lx\n", pfn);
-	return memory_failure(pfn, 0);
+	err = memory_failure(pfn, 0);
+	return (err == -EOPNOTSUPP) ? 0 : err;
 }
 
 static int hwpoison_unpoison(void *data, u64 val)
diff --git a/mm/madvise.c b/mm/madvise.c
index ae35d72627ef..e7cb7a0751d6 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -1096,6 +1096,8 @@ static int madvise_inject_error(int behavior,
 			pr_info("Injecting memory failure for pfn %#lx at process virtual address %#lx\n",
 				 pfn, start);
 			ret = memory_failure(pfn, MF_COUNT_INCREASED);
+			if (ret == -EOPNOTSUPP)
+				ret = 0;
 		}
 
 		if (ret)
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 662afe7b514f..7e16d31df0f3 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1528,7 +1528,7 @@ static int memory_failure_hugetlb(unsigned long pfn, int flags)
 				if (TestClearPageHWPoison(head))
 					num_poisoned_pages_dec();
 				unlock_page(head);
-				return 0;
+				return -EOPNOTSUPP;
 			}
 			unlock_page(head);
 			res = MF_FAILED;
@@ -1615,7 +1615,7 @@ static int memory_failure_dev_pagemap(unsigned long pfn, int flags,
 		goto out;
 
 	if (hwpoison_filter(page)) {
-		rc = 0;
+		rc = -EOPNOTSUPP;
 		goto unlock;
 	}
 
@@ -1688,6 +1688,10 @@ static DEFINE_MUTEX(mf_mutex);
  *
  * Must run in process context (e.g. a work queue) with interrupts
  * enabled and no spinlocks hold.
+ *
+ * Return: 0 for successfully handled the memory error,
+ *         -EOPNOTSUPP for memory_filter() filtered the error event,
+ *         < 0(except -EOPNOTSUPP) on failure.
  */
 int memory_failure(unsigned long pfn, int flags)
 {
@@ -1843,6 +1847,7 @@ int memory_failure(unsigned long pfn, int flags)
 			num_poisoned_pages_dec();
 		unlock_page(p);
 		put_page(p);
+		res = -EOPNOTSUPP;
 		goto unlock_mutex;
 	}
 
-- 
2.27.0

Re: [PATCH v5 1/2] mm/hwpoison: Avoid the impact of hwpoison_filter() return value on mce handler

[Borislav Petkov]

On Wed, Feb 23, 2022 at 03:21:35AM -0500, luofei wrote:
> When the hwpoison page meets the filter conditions, it should
> not be regarded as successful memory_failure() processing for
> mce handler, but should return a distinct value, otherwise
> mce handler regards the error page has been identified and
> isolated, which may lead to calling set_mce_nospec() to change
> page attribute, etc.
> 
> Here memory_failure() return -EOPNOTSUPP to indicate that the
> error event is filtered, mce handler should not take any action
> for this situation and hwpoison injector should treat as correct.
> 
> Signed-off-by: luofei <luofei@unicloud.com>
> ---
>  arch/x86/kernel/cpu/mce/core.c | 8 +++++---
>  drivers/base/memory.c          | 2 ++
>  mm/hwpoison-inject.c           | 3 ++-
>  mm/madvise.c                   | 2 ++
>  mm/memory-failure.c            | 9 +++++++--
>  5 files changed, 18 insertions(+), 6 deletions(-)

Much better, thanks.

Acked-by: Borislav Petkov <bp@suse.de>

-- 
Regards/Gruss,
    Boris.

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