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

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Message-ID: <ac7351c1-cffe-4da6-9397-f9421e53f59f@redhat.com>
Date: Fri, 30 May 2025 21:56:32 +0200
From: David Hildenbrand <david@...hat.com>
To: Zi Yan <ziy@...dia.com>, Johannes Weiner <hannes@...xchg.org>,
 Vlastimil Babka <vbabka@...e.cz>, linux-mm@...ck.org
Cc: 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 v6 6/6] mm/page_isolation: remove migratetype parameter
 from more functions.

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@...dia.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.

> +
>   /* 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 :)

-- 
Cheers,

David / dhildenb