[PATCH 1/3] mm: memory-failure: make put_ref_page() more useful

[PATCH 1/3] mm: memory-failure: make put_ref_page() more useful

[Kefeng Wang]

Pass pfn/flags to put_ref_page(), then check MF_COUNT_INCREASED
and drop refcount to make the code look cleaner.

Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
 mm/memory-failure.c | 34 +++++++++++++++++-----------------
 1 file changed, 17 insertions(+), 17 deletions(-)

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index bead6bccc7f2..b94152abb1c9 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1913,17 +1913,25 @@ static inline unsigned long free_raw_hwp_pages(struct page *hpage, bool flag)
 }
 #endif	/* CONFIG_HUGETLB_PAGE */
 
+/* Drop the extra refcount in case we come from madvise() */
+static void put_ref_page(unsigned long pfn, int flags)
+{
+	struct page *page;
+
+	if (!(flags & MF_COUNT_INCREASED))
+		return;
+
+	page = pfn_to_page(pfn);
+	if (page)
+		put_page(page);
+}
+
 static int memory_failure_dev_pagemap(unsigned long pfn, int flags,
 		struct dev_pagemap *pgmap)
 {
-	struct page *page = pfn_to_page(pfn);
 	int rc = -ENXIO;
 
-	if (flags & MF_COUNT_INCREASED)
-		/*
-		 * Drop the extra refcount in case we come from madvise().
-		 */
-		put_page(page);
+	put_ref_page(pfn, flags);
 
 	/* device metadata space is not recoverable */
 	if (!pgmap_pfn_valid(pgmap, pfn))
@@ -2516,12 +2524,6 @@ static int soft_offline_in_use_page(struct page *page)
 	return ret;
 }
 
-static void put_ref_page(struct page *page)
-{
-	if (page)
-		put_page(page);
-}
-
 /**
  * soft_offline_page - Soft offline a page.
  * @pfn: pfn to soft-offline
@@ -2550,19 +2552,17 @@ int soft_offline_page(unsigned long pfn, int flags)
 {
 	int ret;
 	bool try_again = true;
-	struct page *page, *ref_page = NULL;
+	struct page *page;
 
 	WARN_ON_ONCE(!pfn_valid(pfn) && (flags & MF_COUNT_INCREASED));
 
 	if (!pfn_valid(pfn))
 		return -ENXIO;
-	if (flags & MF_COUNT_INCREASED)
-		ref_page = pfn_to_page(pfn);
 
 	/* Only online pages can be soft-offlined (esp., not ZONE_DEVICE). */
 	page = pfn_to_online_page(pfn);
 	if (!page) {
-		put_ref_page(ref_page);
+		put_ref_page(pfn, flags);
 		return -EIO;
 	}
 
@@ -2570,7 +2570,7 @@ int soft_offline_page(unsigned long pfn, int flags)
 
 	if (PageHWPoison(page)) {
 		pr_info("%s: %#lx page already poisoned\n", __func__, pfn);
-		put_ref_page(ref_page);
+		put_ref_page(pfn, flags);
 		mutex_unlock(&mf_mutex);
 		return 0;
 	}
-- 
2.35.3

[PATCH 2/3] mm: memory-failure: avoid pfn_valid() twice in soft_offline_page()

[Kefeng Wang]

Simplify WARN_ON_ONCE(flags & MF_COUNT_INCREASED) under !pfn_valid().

Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
 mm/memory-failure.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index b94152abb1c9..ca0199d0f79d 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -2554,10 +2554,10 @@ int soft_offline_page(unsigned long pfn, int flags)
 	bool try_again = true;
 	struct page *page;
 
-	WARN_ON_ONCE(!pfn_valid(pfn) && (flags & MF_COUNT_INCREASED));
-
-	if (!pfn_valid(pfn))
+	if (!pfn_valid(pfn)) {
+		WARN_ON_ONCE(flags & MF_COUNT_INCREASED);
 		return -ENXIO;
+	}
 
 	/* Only online pages can be soft-offlined (esp., not ZONE_DEVICE). */
 	page = pfn_to_online_page(pfn);
-- 
2.35.3

Re: [PATCH 2/3] mm: memory-failure: avoid pfn_valid() twice in soft_offline_page()

[HORIGUCHI NAOYA(堀口 直也)]

On Fri, Oct 21, 2022 at 04:46:10PM +0800, Kefeng Wang wrote:
> Simplify WARN_ON_ONCE(flags & MF_COUNT_INCREASED) under !pfn_valid().
> 
> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>

Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>

Re: [PATCH 2/3] mm: memory-failure: avoid pfn_valid() twice in soft_offline_page()

[Miaohe Lin]

On 2022/10/21 16:46, Kefeng Wang wrote:
> Simplify WARN_ON_ONCE(flags & MF_COUNT_INCREASED) under !pfn_valid().
> 
> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>

Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>

Thanks,
Miaohe Lin

[PATCH 3/3] mm: memory-failure: make action_result() return int

[Kefeng Wang]

Check mf_result in action_result(), only return 0 when MF_RECOVERED,
or return -EBUSY, which will simplify code a bit.

Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
 mm/memory-failure.c | 42 ++++++++++++++++--------------------------
 1 file changed, 16 insertions(+), 26 deletions(-)

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index ca0199d0f79d..3f469e2da047 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1182,14 +1182,16 @@ static struct page_state error_states[] = {
  * "Dirty/Clean" indication is not 100% accurate due to the possibility of
  * setting PG_dirty outside page lock. See also comment above set_page_dirty().
  */
-static void action_result(unsigned long pfn, enum mf_action_page_type type,
-			  enum mf_result result)
+static int action_result(unsigned long pfn, enum mf_action_page_type type,
+			 enum mf_result result)
 {
 	trace_memory_failure_event(pfn, type, result);
 
 	num_poisoned_pages_inc();
 	pr_err("%#lx: recovery action for %s: %s\n",
 		pfn, action_page_types[type], action_name[result]);
+
+	return result == MF_RECOVERED ? 0 : -EBUSY;
 }
 
 static int page_action(struct page_state *ps, struct page *p,
@@ -1856,8 +1858,7 @@ static int try_memory_failure_hugetlb(unsigned long pfn, int flags, int *hugetlb
 			flags |= MF_NO_RETRY;
 			goto retry;
 		}
-		action_result(pfn, MF_MSG_UNKNOWN, MF_IGNORED);
-		return res;
+		return action_result(pfn, MF_MSG_UNKNOWN, MF_IGNORED);
 	}
 
 	head = compound_head(p);
@@ -1883,22 +1884,18 @@ static int try_memory_failure_hugetlb(unsigned long pfn, int flags, int *hugetlb
 		} else {
 			res = MF_FAILED;
 		}
-		action_result(pfn, MF_MSG_FREE_HUGE, res);
-		return res == MF_RECOVERED ? 0 : -EBUSY;
+		return action_result(pfn, MF_MSG_FREE_HUGE, res);
 	}
 
 	page_flags = head->flags;
 
 	if (!hwpoison_user_mappings(p, pfn, flags, head)) {
-		action_result(pfn, MF_MSG_UNMAP_FAILED, MF_IGNORED);
-		res = -EBUSY;
-		goto out;
+		res = action_result(pfn, MF_MSG_UNMAP_FAILED, MF_IGNORED);
+		unlock_page(head);
+		return res;
 	}
 
 	return identify_page_state(pfn, p, page_flags);
-out:
-	unlock_page(head);
-	return res;
 }
 
 #else
@@ -2063,16 +2060,13 @@ int memory_failure(unsigned long pfn, int flags)
 					}
 					res = MF_FAILED;
 				}
-				action_result(pfn, MF_MSG_BUDDY, res);
-				res = res == MF_RECOVERED ? 0 : -EBUSY;
+				res = action_result(pfn, MF_MSG_BUDDY, res);
 			} else {
-				action_result(pfn, MF_MSG_KERNEL_HIGH_ORDER, MF_IGNORED);
-				res = -EBUSY;
+				res = action_result(pfn, MF_MSG_KERNEL_HIGH_ORDER, MF_IGNORED);
 			}
 			goto unlock_mutex;
 		} else if (res < 0) {
-			action_result(pfn, MF_MSG_UNKNOWN, MF_IGNORED);
-			res = -EBUSY;
+			res = action_result(pfn, MF_MSG_UNKNOWN, MF_IGNORED);
 			goto unlock_mutex;
 		}
 	}
@@ -2093,8 +2087,7 @@ int memory_failure(unsigned long pfn, int flags)
 		 */
 		SetPageHasHWPoisoned(hpage);
 		if (try_to_split_thp_page(p) < 0) {
-			action_result(pfn, MF_MSG_UNSPLIT_THP, MF_IGNORED);
-			res = -EBUSY;
+			res = action_result(pfn, MF_MSG_UNSPLIT_THP, MF_IGNORED);
 			goto unlock_mutex;
 		}
 		VM_BUG_ON_PAGE(!page_count(p), p);
@@ -2127,8 +2120,7 @@ int memory_failure(unsigned long pfn, int flags)
 			retry = false;
 			goto try_again;
 		}
-		action_result(pfn, MF_MSG_DIFFERENT_COMPOUND, MF_IGNORED);
-		res = -EBUSY;
+		res = action_result(pfn, MF_MSG_DIFFERENT_COMPOUND, MF_IGNORED);
 		goto unlock_page;
 	}
 
@@ -2168,8 +2160,7 @@ int memory_failure(unsigned long pfn, int flags)
 	 * Abort on fail: __filemap_remove_folio() assumes unmapped page.
 	 */
 	if (!hwpoison_user_mappings(p, pfn, flags, p)) {
-		action_result(pfn, MF_MSG_UNMAP_FAILED, MF_IGNORED);
-		res = -EBUSY;
+		res = action_result(pfn, MF_MSG_UNMAP_FAILED, MF_IGNORED);
 		goto unlock_page;
 	}
 
@@ -2177,8 +2168,7 @@ int memory_failure(unsigned long pfn, int flags)
 	 * Torn down by someone else?
 	 */
 	if (PageLRU(p) && !PageSwapCache(p) && p->mapping == NULL) {
-		action_result(pfn, MF_MSG_TRUNCATED_LRU, MF_IGNORED);
-		res = -EBUSY;
+		res = action_result(pfn, MF_MSG_TRUNCATED_LRU, MF_IGNORED);
 		goto unlock_page;
 	}
 
-- 
2.35.3

Re: [PATCH 3/3] mm: memory-failure: make action_result() return int

[HORIGUCHI NAOYA(堀口 直也)]

On Fri, Oct 21, 2022 at 04:46:11PM +0800, Kefeng Wang wrote:
> Check mf_result in action_result(), only return 0 when MF_RECOVERED,
> or return -EBUSY, which will simplify code a bit.
> 
> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>

Thanks for the cleanup, Kefeng.
I basically agree with the change. I have one comment below ...

> ---
>  mm/memory-failure.c | 42 ++++++++++++++++--------------------------
>  1 file changed, 16 insertions(+), 26 deletions(-)
> 
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index ca0199d0f79d..3f469e2da047 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -1182,14 +1182,16 @@ static struct page_state error_states[] = {
>   * "Dirty/Clean" indication is not 100% accurate due to the possibility of
>   * setting PG_dirty outside page lock. See also comment above set_page_dirty().
>   */
> -static void action_result(unsigned long pfn, enum mf_action_page_type type,
> -			  enum mf_result result)
> +static int action_result(unsigned long pfn, enum mf_action_page_type type,
> +			 enum mf_result result)
>  {
>  	trace_memory_failure_event(pfn, type, result);
>  
>  	num_poisoned_pages_inc();
>  	pr_err("%#lx: recovery action for %s: %s\n",
>  		pfn, action_page_types[type], action_name[result]);
> +
> +	return result == MF_RECOVERED ? 0 : -EBUSY;

I think that MF_DELAYED may be considered as success (returning 0), then
page_action() can be cleaned up a little more (like below?)

    static int page_action(struct page_state *ps, struct page *p,
                            unsigned long pfn)
    {
            int result;
    
            /* page p should be unlocked after returning from ps->action().  */
            result = ps->action(ps, p);
    
            /* Could do more checks here if page looks ok */
            /*
             * Could adjust zone counters here to correct for the missing page.
             */
    
            return action_result(pfn, ps->type, result);
    }

Existing direct callers (I mean action_result() called from other than
page_action()) are never called with result==MF_DELAYED, so this change
should not affect them.

Does it make sense for you?

Thanks,
Naoya Horiguchi

Re: [PATCH 3/3] mm: memory-failure: make action_result() return int

[Kefeng Wang]

On 2022/10/24 7:56, HORIGUCHI NAOYA(堀口 直也) wrote:
> On Fri, Oct 21, 2022 at 04:46:11PM +0800, Kefeng Wang wrote:
>> Check mf_result in action_result(), only return 0 when MF_RECOVERED,
>> or return -EBUSY, which will simplify code a bit.
>>
>> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
> Thanks for the cleanup, Kefeng.
> I basically agree with the change. I have one comment below ...
>
>> ---
>>   mm/memory-failure.c | 42 ++++++++++++++++--------------------------
>>   1 file changed, 16 insertions(+), 26 deletions(-)
>>
>> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
>> index ca0199d0f79d..3f469e2da047 100644
>> --- a/mm/memory-failure.c
>> +++ b/mm/memory-failure.c
>> @@ -1182,14 +1182,16 @@ static struct page_state error_states[] = {
>>    * "Dirty/Clean" indication is not 100% accurate due to the possibility of
>>    * setting PG_dirty outside page lock. See also comment above set_page_dirty().
>>    */
>> -static void action_result(unsigned long pfn, enum mf_action_page_type type,
>> -			  enum mf_result result)
>> +static int action_result(unsigned long pfn, enum mf_action_page_type type,
>> +			 enum mf_result result)
>>   {
>>   	trace_memory_failure_event(pfn, type, result);
>>   
>>   	num_poisoned_pages_inc();
>>   	pr_err("%#lx: recovery action for %s: %s\n",
>>   		pfn, action_page_types[type], action_name[result]);
>> +
>> +	return result == MF_RECOVERED ? 0 : -EBUSY;
> I think that MF_DELAYED may be considered as success (returning 0), then
> page_action() can be cleaned up a little more (like below?)
Yes, MF_DELAYED should be considered as success,
>
>      static int page_action(struct page_state *ps, struct page *p,
>                              unsigned long pfn)
>      {
>              int result;
>      
>              /* page p should be unlocked after returning from ps->action().  */
>              result = ps->action(ps, p);
>      
>              /* Could do more checks here if page looks ok */
>              /*
>               * Could adjust zone counters here to correct for the missing page.
>               */
>      
>              return action_result(pfn, ps->type, result);
>      }
>
> Existing direct callers (I mean action_result() called from other than
> page_action()) are never called with result==MF_DELAYED, so this change
> should not affect them.
I will refresh this patch, thanks.
> Does it make sense for you?
>
> Thanks,
> Naoya Horiguchi

[PATCH v2] mm: memory-failure: make action_result() return int

[Kefeng Wang]

Check mf_result in action_result(), only return 0 when
MF_RECOVERED/MF_DELAYED, or return -EBUSY, which will
simplify code a bit.

Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
v2: 
- MF_DELAYED is considered as success, suggested by HORIGUCHI
- adjust order between unlock_page(head) and action_result()
  after !hwpoison_user_mappings() to clean code more in
  try_memory_failure_hugetlb()

 mm/memory-failure.c | 45 ++++++++++++++++-----------------------------
 1 file changed, 16 insertions(+), 29 deletions(-)

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index ca0199d0f79d..3cfa1b9ac513 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1182,14 +1182,16 @@ static struct page_state error_states[] = {
  * "Dirty/Clean" indication is not 100% accurate due to the possibility of
  * setting PG_dirty outside page lock. See also comment above set_page_dirty().
  */
-static void action_result(unsigned long pfn, enum mf_action_page_type type,
-			  enum mf_result result)
+static int action_result(unsigned long pfn, enum mf_action_page_type type,
+			 enum mf_result result)
 {
 	trace_memory_failure_event(pfn, type, result);
 
 	num_poisoned_pages_inc();
 	pr_err("%#lx: recovery action for %s: %s\n",
 		pfn, action_page_types[type], action_name[result]);
+
+	return (result == MF_RECOVERED || result == MF_DELAYED) ? 0 : -EBUSY;
 }
 
 static int page_action(struct page_state *ps, struct page *p,
@@ -1200,14 +1202,12 @@ static int page_action(struct page_state *ps, struct page *p,
 	/* page p should be unlocked after returning from ps->action().  */
 	result = ps->action(ps, p);
 
-	action_result(pfn, ps->type, result);
-
 	/* Could do more checks here if page looks ok */
 	/*
 	 * Could adjust zone counters here to correct for the missing page.
 	 */
 
-	return (result == MF_RECOVERED || result == MF_DELAYED) ? 0 : -EBUSY;
+	return action_result(pfn, ps->type, result);
 }
 
 static inline bool PageHWPoisonTakenOff(struct page *page)
@@ -1856,8 +1856,7 @@ static int try_memory_failure_hugetlb(unsigned long pfn, int flags, int *hugetlb
 			flags |= MF_NO_RETRY;
 			goto retry;
 		}
-		action_result(pfn, MF_MSG_UNKNOWN, MF_IGNORED);
-		return res;
+		return action_result(pfn, MF_MSG_UNKNOWN, MF_IGNORED);
 	}
 
 	head = compound_head(p);
@@ -1883,22 +1882,17 @@ static int try_memory_failure_hugetlb(unsigned long pfn, int flags, int *hugetlb
 		} else {
 			res = MF_FAILED;
 		}
-		action_result(pfn, MF_MSG_FREE_HUGE, res);
-		return res == MF_RECOVERED ? 0 : -EBUSY;
+		return action_result(pfn, MF_MSG_FREE_HUGE, res);
 	}
 
 	page_flags = head->flags;
 
 	if (!hwpoison_user_mappings(p, pfn, flags, head)) {
-		action_result(pfn, MF_MSG_UNMAP_FAILED, MF_IGNORED);
-		res = -EBUSY;
-		goto out;
+		unlock_page(head);
+		return action_result(pfn, MF_MSG_UNMAP_FAILED, MF_IGNORED);
 	}
 
 	return identify_page_state(pfn, p, page_flags);
-out:
-	unlock_page(head);
-	return res;
 }
 
 #else
@@ -2063,16 +2057,13 @@ int memory_failure(unsigned long pfn, int flags)
 					}
 					res = MF_FAILED;
 				}
-				action_result(pfn, MF_MSG_BUDDY, res);
-				res = res == MF_RECOVERED ? 0 : -EBUSY;
+				res = action_result(pfn, MF_MSG_BUDDY, res);
 			} else {
-				action_result(pfn, MF_MSG_KERNEL_HIGH_ORDER, MF_IGNORED);
-				res = -EBUSY;
+				res = action_result(pfn, MF_MSG_KERNEL_HIGH_ORDER, MF_IGNORED);
 			}
 			goto unlock_mutex;
 		} else if (res < 0) {
-			action_result(pfn, MF_MSG_UNKNOWN, MF_IGNORED);
-			res = -EBUSY;
+			res = action_result(pfn, MF_MSG_UNKNOWN, MF_IGNORED);
 			goto unlock_mutex;
 		}
 	}
@@ -2093,8 +2084,7 @@ int memory_failure(unsigned long pfn, int flags)
 		 */
 		SetPageHasHWPoisoned(hpage);
 		if (try_to_split_thp_page(p) < 0) {
-			action_result(pfn, MF_MSG_UNSPLIT_THP, MF_IGNORED);
-			res = -EBUSY;
+			res = action_result(pfn, MF_MSG_UNSPLIT_THP, MF_IGNORED);
 			goto unlock_mutex;
 		}
 		VM_BUG_ON_PAGE(!page_count(p), p);
@@ -2127,8 +2117,7 @@ int memory_failure(unsigned long pfn, int flags)
 			retry = false;
 			goto try_again;
 		}
-		action_result(pfn, MF_MSG_DIFFERENT_COMPOUND, MF_IGNORED);
-		res = -EBUSY;
+		res = action_result(pfn, MF_MSG_DIFFERENT_COMPOUND, MF_IGNORED);
 		goto unlock_page;
 	}
 
@@ -2168,8 +2157,7 @@ int memory_failure(unsigned long pfn, int flags)
 	 * Abort on fail: __filemap_remove_folio() assumes unmapped page.
 	 */
 	if (!hwpoison_user_mappings(p, pfn, flags, p)) {
-		action_result(pfn, MF_MSG_UNMAP_FAILED, MF_IGNORED);
-		res = -EBUSY;
+		res = action_result(pfn, MF_MSG_UNMAP_FAILED, MF_IGNORED);
 		goto unlock_page;
 	}
 
@@ -2177,8 +2165,7 @@ int memory_failure(unsigned long pfn, int flags)
 	 * Torn down by someone else?
 	 */
 	if (PageLRU(p) && !PageSwapCache(p) && p->mapping == NULL) {
-		action_result(pfn, MF_MSG_TRUNCATED_LRU, MF_IGNORED);
-		res = -EBUSY;
+		res = action_result(pfn, MF_MSG_TRUNCATED_LRU, MF_IGNORED);
 		goto unlock_page;
 	}
 
-- 
2.35.3

Re: [PATCH v2] mm: memory-failure: make action_result() return int

[HORIGUCHI NAOYA(堀口 直也)]

On Mon, Oct 24, 2022 at 11:51:38AM +0800, Kefeng Wang wrote:
> Check mf_result in action_result(), only return 0 when
> MF_RECOVERED/MF_DELAYED, or return -EBUSY, which will
> simplify code a bit.
> 
> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
> ---
> v2: 
> - MF_DELAYED is considered as success, suggested by HORIGUCHI
> - adjust order between unlock_page(head) and action_result()
>   after !hwpoison_user_mappings() to clean code more in
>   try_memory_failure_hugetlb()
> 

Thank you for the update. The patch looks good to me.

Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>

Re: [PATCH v2] mm: memory-failure: make action_result() return int

[Miaohe Lin]

On 2022/10/24 11:51, Kefeng Wang wrote:
> Check mf_result in action_result(), only return 0 when
> MF_RECOVERED/MF_DELAYED, or return -EBUSY, which will
> simplify code a bit.
> 
> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>

Thanks for cleanup. This really makes code cleaner.

Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>

Thanks,
Miaohe Lin

Re: [PATCH 1/3] mm: memory-failure: make put_ref_page() more useful

[HORIGUCHI NAOYA(堀口 直也)]

On Fri, Oct 21, 2022 at 04:46:09PM +0800, Kefeng Wang wrote:
> Pass pfn/flags to put_ref_page(), then check MF_COUNT_INCREASED
> and drop refcount to make the code look cleaner.
> 
> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>

Looks good to me, thank you.

Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>

Re: [PATCH 1/3] mm: memory-failure: make put_ref_page() more useful

[Miaohe Lin]

On 2022/10/21 16:46, Kefeng Wang wrote:
> Pass pfn/flags to put_ref_page(), then check MF_COUNT_INCREASED
> and drop refcount to make the code look cleaner.
> 
> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
> ---
>  mm/memory-failure.c | 34 +++++++++++++++++-----------------
>  1 file changed, 17 insertions(+), 17 deletions(-)
> 
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index bead6bccc7f2..b94152abb1c9 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -1913,17 +1913,25 @@ static inline unsigned long free_raw_hwp_pages(struct page *hpage, bool flag)
>  }
>  #endif	/* CONFIG_HUGETLB_PAGE */
>  
> +/* Drop the extra refcount in case we come from madvise() */
> +static void put_ref_page(unsigned long pfn, int flags)
> +{
> +	struct page *page;
> +
> +	if (!(flags & MF_COUNT_INCREASED))
> +		return;
> +
> +	page = pfn_to_page(pfn);
> +	if (page)

IMO above check is unneeded. Page can't be NULL as pfn is valid. But this is trival and this patch looks
good to me. Thanks.

Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>

Thanks,
Miaohe Lin