linux-kernel - Re: [PATCH v7 6/6] mm/page_isolation: remove migratetype parameter from more functions.

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Message-ID: <8297D7ED-2220-469A-922D-98C5E5B7671C@nvidia.com>
Date: Mon, 02 Jun 2025 17:09:15 -0400
From: Zi Yan <ziy@...dia.com>
To: David Hildenbrand <david@...hat.com>
Cc: Johannes Weiner <hannes@...xchg.org>, Vlastimil Babka <vbabka@...e.cz>,
 linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
 Oscar Salvador <osalvador@...e.de>,
 Baolin Wang <baolin.wang@...ux.alibaba.com>,
 "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
 Mel Gorman <mgorman@...hsingularity.net>,
 Suren Baghdasaryan <surenb@...gle.com>, Michal Hocko <mhocko@...e.com>,
 Brendan Jackman <jackmanb@...gle.com>, Richard Chang <richardycc@...gle.com>,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 6/6] mm/page_isolation: remove migratetype parameter
 from more functions.

On 2 Jun 2025, at 16:59, David Hildenbrand wrote:

> On 02.06.25 18:59, Zi Yan wrote:
>> On 2 Jun 2025, at 11:18, 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 PB_ISOLATE_MODE_CMA_ALLOC 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
>>> PB_ISOLATE_MODE_MEM_OFFLINE, since only PB_ISOLATE_MODE_MEM_OFFLINE
>>> reports isolation failures.
>>>
>>> alloc_contig_range() no longer needs migratetype. Replace it with
>>> PB_ISOLATE_MODE_CMA_ALLOC to tell if an allocation is for CMA. So does
>>> __alloc_contig_migrate_range().
>>
>> This paragraph should be changed to:
>>
>> alloc_contig_range() no longer needs migratetype. Replace it with
>> a newly defined acr_flags_t to tell if an allocation is for CMA. So does
>> __alloc_contig_migrate_range(). Add ACR_OTHER (set to 0) to indicate
>> other cases.
>>

<snip>

>> +
>> +typedef unsigned int __bitwise acr_flags_t;
>> +#define ACR_OTHER	((__force acr_flags_t)0)	// other allocations
>> +#define ACR_CMA		((__force acr_flags_t)BIT(0))	// allocate for CMA
>
> For FPI I called that "FPI_NONE" -- no special request -- and similarly for RMAP "RMAP_NONE".
>
> So if ACR_CMA is set, it's a CMA allocation, otherwise just an ordinary one.
>
>
> Apart from that LGTM.

Make sense. Thanks. This is the rename fixup.

From ba6ff91746640e5baccbf55a48f9290a04ec1363 Mon Sep 17 00:00:00 2001
From: Zi Yan <ziy@...dia.com>
Date: Mon, 2 Jun 2025 17:05:19 -0400
Subject: [PATCH] rename ACR_OTHER to ACR_NONE.

Signed-off-by: Zi Yan <ziy@...dia.com>
---
 drivers/virtio/virtio_mem.c | 2 +-
 include/linux/gfp.h         | 2 +-
 mm/page_alloc.c             | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c
index 6bce70b139b2..42ebaafb9591 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, ACR_OTHER,
+		rc = alloc_contig_range(pfn, pfn + nr_pages, ACR_NONE,
 					GFP_KERNEL);
 		if (rc == -ENOMEM)
 			/* whoops, out of memory */
diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 95065cec85e5..ccf35cc351ff 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -425,7 +425,7 @@ extern gfp_t vma_thp_gfp_mask(struct vm_area_struct *vma);
 #ifdef CONFIG_CONTIG_ALLOC

 typedef unsigned int __bitwise acr_flags_t;
-#define ACR_OTHER	((__force acr_flags_t)0)	// other allocations
+#define ACR_NONE	((__force acr_flags_t)0)	// ordinary allocation request
 #define ACR_CMA		((__force acr_flags_t)BIT(0))	// allocate for CMA

 /* The below functions must be run on a range from a single zone. */
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index c12442fdb579..0867e2b2e187 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -6997,7 +6997,7 @@ 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, ACR_NONE,
 					 gfp_mask);
 }

-- 
2.47.2



Best Regards,
Yan, Zi