Re: [PATCH v6 6/6] mm/page_isolation: remove migratetype parameter from more functions.

[Zi Yan <ziy@nvidia.com>]

On 30 May 2025, at 16:08, David Hildenbrand wrote:

> On 30.05.25 21:58, Zi Yan wrote:
>> On 30 May 2025, at 15:56, David Hildenbrand wrote:
>>
>>> On 30.05.25 18:22, Zi Yan wrote:
>>>> migratetype is no longer overwritten during pageblock isolation,
>>>> start_isolate_page_range(), has_unmovable_pages(), and
>>>> set_migratetype_isolate() no longer need which migratetype to restore
>>>> during isolation failure.
>>>>
>>>> For has_unmoable_pages(), it needs to know if the isolation is for CMA
>>>> allocation, so adding CMA_ALLOCATION to provide the information. At the
>>>> same time change isolation flags to enum pb_isolate_mode
>>>> (PB_ISOLATE_MODE_MEM_OFFLINE, PB_ISOLATE_MODE_CMA_ALLOC,
>>>> PB_ISOLATE_MODE_OTHER). Remove REPORT_FAILURE and check
>>>> MEMORY_OFFLINE instead, since only PB_ISOLATE_MODE_MEM_OFFLINE reports
>>>> isolation failures.
>>>>
>>>> alloc_contig_range() no longer needs migratetype. Replace it with
>>>> enum acr_flags_t to tell if an allocation is for CMA. So does
>>>> __alloc_contig_migrate_range().
>>>>
>>>> Signed-off-by: Zi Yan <ziy@nvidia.com>
>>>> ---
>>>>    drivers/virtio/virtio_mem.c    |  2 +-
>>>>    include/linux/gfp.h            |  9 ++++-
>>>>    include/linux/page-isolation.h | 20 ++++++++--
>>>>    include/trace/events/kmem.h    | 14 ++++---
>>>>    mm/cma.c                       |  2 +-
>>>>    mm/memory_hotplug.c            |  6 +--
>>>>    mm/page_alloc.c                | 27 ++++++-------
>>>>    mm/page_isolation.c            | 70 +++++++++++++++-------------------
>>>>    8 files changed, 82 insertions(+), 68 deletions(-)
>>>>
>>>> diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c
>>>> index 56d0dbe62163..6bce70b139b2 100644
>>>> --- a/drivers/virtio/virtio_mem.c
>>>> +++ b/drivers/virtio/virtio_mem.c
>>>> @@ -1243,7 +1243,7 @@ static int virtio_mem_fake_offline(struct virtio_mem *vm, unsigned long pfn,
>>>>    		if (atomic_read(&vm->config_changed))
>>>>    			return -EAGAIN;
>>>>   -		rc = alloc_contig_range(pfn, pfn + nr_pages, MIGRATE_MOVABLE,
>>>> +		rc = alloc_contig_range(pfn, pfn + nr_pages, ACR_OTHER,
>>>>    					GFP_KERNEL);
>>>>    		if (rc == -ENOMEM)
>>>>    			/* whoops, out of memory */
>>>> diff --git a/include/linux/gfp.h b/include/linux/gfp.h
>>>> index be160e8d8bcb..51990d571e3e 100644
>>>> --- a/include/linux/gfp.h
>>>> +++ b/include/linux/gfp.h
>>>> @@ -423,9 +423,16 @@ static inline bool gfp_compaction_allowed(gfp_t gfp_mask)
>>>>    extern gfp_t vma_thp_gfp_mask(struct vm_area_struct *vma);
>>>>     #ifdef CONFIG_CONTIG_ALLOC
>>>> +
>>>> +enum acr_flags_t {
>>>> +	ACR_CMA,	// CMA allocation
>>>> +	ACR_OTHER,	// other allocation
>>>> +};
>>>
>>> Hm, enum != flags.
>>>
>>> If you want to use flags, then just have ACR_CMA. ACR_OTHER is implied if not set.
>>>
>>> And ACR_CMA would then have to be "1" etc.
>>
>> I have a fixup to change acr_flags_t to acr_mode.
>>
>>>
>>>> +
>>>>    /* The below functions must be run on a range from a single zone. */
>>>>    extern int alloc_contig_range_noprof(unsigned long start, unsigned long end,
>>>> -			      unsigned migratetype, gfp_t gfp_mask);
>>>> +				     enum acr_flags_t alloc_flags,
>>>> +				     gfp_t gfp_mask);
>>>>    #define alloc_contig_range(...)			alloc_hooks(alloc_contig_range_noprof(__VA_ARGS__))
>>>>     extern struct page *alloc_contig_pages_noprof(unsigned long nr_pages, gfp_t gfp_mask,
>>>> diff --git a/include/linux/page-isolation.h b/include/linux/page-isolation.h
>>>> index 7a681a49e73c..3e2f960e166c 100644
>>>> --- a/include/linux/page-isolation.h
>>>> +++ b/include/linux/page-isolation.h
>>>> @@ -38,8 +38,20 @@ static inline void set_pageblock_isolate(struct page *page)
>>>>    }
>>>>    #endif
>>>>   -#define MEMORY_OFFLINE	0x1
>>>> -#define REPORT_FAILURE	0x2
>>>> +/*
>>>> + * Pageblock isolation modes:
>>>> + * PB_ISOLATE_MODE_MEM_OFFLINE - isolate to offline (!allocate) memory
>>>> + *				 e.g., skip over PageHWPoison() pages and
>>>> + *				 PageOffline() pages. Unmovable pages will be
>>>> + *				 reported in this mode.
>>>> + * PB_ISOLATE_MODE_CMA_ALLOC   - isolate for CMA allocations
>>>> + * PB_ISOLATE_MODE_OTHER       - isolate for other purposes
>>>> + */
>>>> +enum pb_isolate_mode {
>>>> +	PB_ISOLATE_MODE_MEM_OFFLINE,
>>>> +	PB_ISOLATE_MODE_CMA_ALLOC,
>>>> +	PB_ISOLATE_MODE_OTHER,
>>>> +};
>>>
>>> It's late on friady, but it looks like we are duplicating things here.
>>>
>>> Let me think about that once my brain is recharged :)
>>
>> Sure. Take your time.
>
> Could we abstract both settings and use a single one? Then, we could simply reject if MEM_OFFLINE is passed into alloc_contig_range().
>
> alloc_contig_pages and page isolation, hmmmm, MEM_OFFLINE is kind-of an allocation. CMA is an allocation.
>
> Just an idea, not sure ...

I think so.

This is the fixup of removing acr_flags_t. It is on top of the original
patch. Take your time. I guess I will send V7 with all fixups next week.

The one strange part is that in virtio_mem_fake_offline,
PB_ISOLATE_MODE_OTHER is used instead of PB_ISOLATE_MODE_MEM_OFFLINE.
I guess you do not want to report failures there.

From b4bed6ec8bd07df40952bff2009905ae4093b3be Mon Sep 17 00:00:00 2001
From: Zi Yan <ziy@nvidia.com>
Date: Fri, 30 May 2025 13:58:11 -0400
Subject: [PATCH] remove acr_flags_t and use enum pb_isolate_mode instead.

Signed-off-by: Zi Yan <ziy@nvidia.com>
---
 drivers/virtio/virtio_mem.c    |  4 ++--
 include/linux/gfp.h            | 19 ++++++++++++++-----
 include/linux/page-isolation.h | 15 ---------------
 include/trace/events/kmem.h    | 12 ++++++------
 mm/cma.c                       |  3 ++-
 mm/page_alloc.c                | 24 ++++++++++++------------
 6 files changed, 36 insertions(+), 41 deletions(-)

diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c
index 6bce70b139b2..535680a54ff5 100644
--- a/drivers/virtio/virtio_mem.c
+++ b/drivers/virtio/virtio_mem.c
@@ -1243,8 +1243,8 @@ static int virtio_mem_fake_offline(struct virtio_mem *vm, unsigned long pfn,
 		if (atomic_read(&vm->config_changed))
 			return -EAGAIN;

-		rc = alloc_contig_range(pfn, pfn + nr_pages, ACR_OTHER,
-					GFP_KERNEL);
+		rc = alloc_contig_range(pfn, pfn + nr_pages,
+					PB_ISOLATE_MODE_OTHER, GFP_KERNEL);
 		if (rc == -ENOMEM)
 			/* whoops, out of memory */
 			return rc;
diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 51990d571e3e..17b92888d6de 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -423,15 +423,24 @@ static inline bool gfp_compaction_allowed(gfp_t gfp_mask)
 extern gfp_t vma_thp_gfp_mask(struct vm_area_struct *vma);

 #ifdef CONFIG_CONTIG_ALLOC
-
-enum acr_flags_t {
-	ACR_CMA,	// CMA allocation
-	ACR_OTHER,	// other allocation
+/*
+ * Pageblock isolation modes:
+ * PB_ISOLATE_MODE_MEM_OFFLINE - isolate to offline (!allocate) memory
+ *				 e.g., skip over PageHWPoison() pages and
+ *				 PageOffline() pages. Unmovable pages will be
+ *				 reported in this mode.
+ * PB_ISOLATE_MODE_CMA_ALLOC   - isolate for CMA allocations
+ * PB_ISOLATE_MODE_OTHER       - isolate for other purposes
+ */
+enum pb_isolate_mode {
+	PB_ISOLATE_MODE_MEM_OFFLINE,
+	PB_ISOLATE_MODE_CMA_ALLOC,
+	PB_ISOLATE_MODE_OTHER,
 };

 /* The below functions must be run on a range from a single zone. */
 extern int alloc_contig_range_noprof(unsigned long start, unsigned long end,
-				     enum acr_flags_t alloc_flags,
+				     enum pb_isolate_mode isol_mode,
 				     gfp_t gfp_mask);
 #define alloc_contig_range(...)			alloc_hooks(alloc_contig_range_noprof(__VA_ARGS__))

diff --git a/include/linux/page-isolation.h b/include/linux/page-isolation.h
index 3e2f960e166c..7ed60a339a02 100644
--- a/include/linux/page-isolation.h
+++ b/include/linux/page-isolation.h
@@ -38,21 +38,6 @@ static inline void set_pageblock_isolate(struct page *page)
 }
 #endif

-/*
- * Pageblock isolation modes:
- * PB_ISOLATE_MODE_MEM_OFFLINE - isolate to offline (!allocate) memory
- *				 e.g., skip over PageHWPoison() pages and
- *				 PageOffline() pages. Unmovable pages will be
- *				 reported in this mode.
- * PB_ISOLATE_MODE_CMA_ALLOC   - isolate for CMA allocations
- * PB_ISOLATE_MODE_OTHER       - isolate for other purposes
- */
-enum pb_isolate_mode {
-	PB_ISOLATE_MODE_MEM_OFFLINE,
-	PB_ISOLATE_MODE_CMA_ALLOC,
-	PB_ISOLATE_MODE_OTHER,
-};
-
 void __meminit init_pageblock_migratetype(struct page *page,
 					  enum migratetype migratetype,
 					  bool isolate);
diff --git a/include/trace/events/kmem.h b/include/trace/events/kmem.h
index 7c4e2e703a23..e0bcbc43a548 100644
--- a/include/trace/events/kmem.h
+++ b/include/trace/events/kmem.h
@@ -312,9 +312,9 @@ TRACE_EVENT(mm_alloc_contig_migrate_range_info,
 		 unsigned long nr_migrated,
 		 unsigned long nr_reclaimed,
 		 unsigned long nr_mapped,
-		 enum acr_flags_t alloc_flags),
+		 enum pb_isolate_mode isol_mode),

-	TP_ARGS(start, end, nr_migrated, nr_reclaimed, nr_mapped, alloc_flags),
+	TP_ARGS(start, end, nr_migrated, nr_reclaimed, nr_mapped, isol_mode),

 	TP_STRUCT__entry(
 		__field(unsigned long, start)
@@ -322,7 +322,7 @@ TRACE_EVENT(mm_alloc_contig_migrate_range_info,
 		__field(unsigned long, nr_migrated)
 		__field(unsigned long, nr_reclaimed)
 		__field(unsigned long, nr_mapped)
-		__field(enum acr_flags_t, alloc_flags)
+		__field(enum pb_isolate_mode, isol_mode)
 	),

 	TP_fast_assign(
@@ -331,13 +331,13 @@ TRACE_EVENT(mm_alloc_contig_migrate_range_info,
 		__entry->nr_migrated = nr_migrated;
 		__entry->nr_reclaimed = nr_reclaimed;
 		__entry->nr_mapped = nr_mapped;
-		__entry->alloc_flags = alloc_flags;
+		__entry->isol_mode = isol_mode;
 	),

-	TP_printk("start=0x%lx end=0x%lx alloc_flags=%d nr_migrated=%lu nr_reclaimed=%lu nr_mapped=%lu",
+	TP_printk("start=0x%lx end=0x%lx isol_mode=%d nr_migrated=%lu nr_reclaimed=%lu nr_mapped=%lu",
 		  __entry->start,
 		  __entry->end,
-		  __entry->alloc_flags,
+		  __entry->isol_mode,
 		  __entry->nr_migrated,
 		  __entry->nr_reclaimed,
 		  __entry->nr_mapped)
diff --git a/mm/cma.c b/mm/cma.c
index 9ee8fad797bc..23aa35193122 100644
--- a/mm/cma.c
+++ b/mm/cma.c
@@ -822,7 +822,8 @@ static int cma_range_alloc(struct cma *cma, struct cma_memrange *cmr,

 		pfn = cmr->base_pfn + (bitmap_no << cma->order_per_bit);
 		mutex_lock(&cma->alloc_mutex);
-		ret = alloc_contig_range(pfn, pfn + count, ACR_CMA, gfp);
+		ret = alloc_contig_range(pfn, pfn + count,
+					 PB_ISOLATE_MODE_CMA_ALLOC, gfp);
 		mutex_unlock(&cma->alloc_mutex);
 		if (ret == 0) {
 			page = pfn_to_page(pfn);
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index dd761f5e6310..619b1a9de9b7 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -6696,12 +6696,12 @@ static void alloc_contig_dump_pages(struct list_head *page_list)

 /*
  * [start, end) must belong to a single zone.
- * @alloc_flags: using acr_flags_t to filter the type of migration in
+ * @isol_mode: using pb_isolate_mode filter the type of migration in
  *		trace_mm_alloc_contig_migrate_range_info.
  */
 static int __alloc_contig_migrate_range(struct compact_control *cc,
 					unsigned long start, unsigned long end,
-					enum acr_flags_t alloc_flags)
+					enum pb_isolate_mode isol_mode)
 {
 	/* This function is based on compact_zone() from compaction.c. */
 	unsigned int nr_reclaimed;
@@ -6773,7 +6773,7 @@ static int __alloc_contig_migrate_range(struct compact_control *cc,
 		putback_movable_pages(&cc->migratepages);
 	}

-	trace_mm_alloc_contig_migrate_range_info(start, end, alloc_flags,
+	trace_mm_alloc_contig_migrate_range_info(start, end, isol_mode,
 						 total_migrated,
 						 total_reclaimed,
 						 total_mapped);
@@ -6844,7 +6844,7 @@ static int __alloc_contig_verify_gfp_mask(gfp_t gfp_mask, gfp_t *gfp_cc_mask)
  * alloc_contig_range() -- tries to allocate given range of pages
  * @start:	start PFN to allocate
  * @end:	one-past-the-last PFN to allocate
- * @alloc_flags:	allocation information
+ * @isol_mode:	allocation information used for pageblock isolation
  * @gfp_mask:	GFP mask. Node/zone/placement hints are ignored; only some
  *		action and reclaim modifiers are supported. Reclaim modifiers
  *		control allocation behavior during compaction/migration/reclaim.
@@ -6861,7 +6861,7 @@ static int __alloc_contig_verify_gfp_mask(gfp_t gfp_mask, gfp_t *gfp_cc_mask)
  * need to be freed with free_contig_range().
  */
 int alloc_contig_range_noprof(unsigned long start, unsigned long end,
-			      enum acr_flags_t alloc_flags, gfp_t gfp_mask)
+			      enum pb_isolate_mode isol_mode, gfp_t gfp_mask)
 {
 	unsigned long outer_start, outer_end;
 	int ret = 0;
@@ -6876,9 +6876,9 @@ int alloc_contig_range_noprof(unsigned long start, unsigned long end,
 		.alloc_contig = true,
 	};
 	INIT_LIST_HEAD(&cc.migratepages);
-	enum pb_isolate_mode mode = (alloc_flags == ACR_CMA) ?
-					    PB_ISOLATE_MODE_CMA_ALLOC :
-					    PB_ISOLATE_MODE_OTHER;
+
+	if (isol_mode == PB_ISOLATE_MODE_MEM_OFFLINE)
+		return -EINVAL;

 	gfp_mask = current_gfp_context(gfp_mask);
 	if (__alloc_contig_verify_gfp_mask(gfp_mask, (gfp_t *)&cc.gfp_mask))
@@ -6905,7 +6905,7 @@ int alloc_contig_range_noprof(unsigned long start, unsigned long end,
 	 * put back to page allocator so that buddy can use them.
 	 */

-	ret = start_isolate_page_range(start, end, mode);
+	ret = start_isolate_page_range(start, end, isol_mode);
 	if (ret)
 		goto done;

@@ -6921,7 +6921,7 @@ int alloc_contig_range_noprof(unsigned long start, unsigned long end,
 	 * allocated.  So, if we fall through be sure to clear ret so that
 	 * -EBUSY is not accidentally used or returned to caller.
 	 */
-	ret = __alloc_contig_migrate_range(&cc, start, end, alloc_flags);
+	ret = __alloc_contig_migrate_range(&cc, start, end, isol_mode);
 	if (ret && ret != -EBUSY)
 		goto done;

@@ -6955,7 +6955,7 @@ int alloc_contig_range_noprof(unsigned long start, unsigned long end,
 	outer_start = find_large_buddy(start);

 	/* Make sure the range is really isolated. */
-	if (test_pages_isolated(outer_start, end, mode)) {
+	if (test_pages_isolated(outer_start, end, isol_mode)) {
 		ret = -EBUSY;
 		goto done;
 	}
@@ -6998,7 +6998,7 @@ static int __alloc_contig_pages(unsigned long start_pfn,
 {
 	unsigned long end_pfn = start_pfn + nr_pages;

-	return alloc_contig_range_noprof(start_pfn, end_pfn, ACR_OTHER,
+	return alloc_contig_range_noprof(start_pfn, end_pfn, PB_ISOLATE_MODE_OTHER,
 					 gfp_mask);
 }

-- 
2.47.2



Best Regards,
Yan, Zi