linux-kernel - Re: [PATCH] mm: remove redundant __GFP

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Message-ID: <aJs9dPMdY_W5uZdc@hyeyoo>
Date: Tue, 12 Aug 2025 22:11:16 +0900
From: Harry Yoo <harry.yoo@...cle.com>
To: Qianfeng Rong <rongqianfeng@...o.com>
Cc: "Matthew Wilcox (Oracle)" <willy@...radead.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Will Deacon <will@...nel.org>,
        "Aneesh Kumar K.V" <aneesh.kumar@...nel.org>,
        Nick Piggin <npiggin@...il.com>, Peter Zijlstra <peterz@...radead.org>,
        David Hildenbrand <david@...hat.com>,
        Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
        Rik van Riel <riel@...riel.com>,
        "Liam R. Howlett" <Liam.Howlett@...cle.com>,
        Vlastimil Babka <vbabka@...e.cz>, Uladzislau Rezki <urezki@...il.com>,
        linux-fsdevel@...r.kernel.org, sj@...nel.org, damon@...ts.linux.dev,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        linux-arch@...r.kernel.org
Subject: Re: [PATCH] mm: remove redundant __GFP_NOWARN

On Tue, Aug 12, 2025 at 05:57:46PM +0800, Qianfeng Rong wrote:
> Commit 16f5dfbc851b ("gfp: include __GFP_NOWARN in GFP_NOWAIT") made
> GFP_NOWAIT implicitly include __GFP_NOWARN.
> 
> Therefore, explicit __GFP_NOWARN combined with GFP_NOWAIT (e.g.,
> `GFP_NOWAIT | __GFP_NOWARN`) is now redundant.  Let's clean up these
> redundant flags across subsystems.
> 
> No functional changes.
> 
> Signed-off-by: Qianfeng Rong <rongqianfeng@...o.com>
> ---

Maybe

.gfp_mask = (GFP_HIGHUSER_MOVABLE & ~__GFP_RECLAIM) |
                        __GFP_NOWARN | __GFP_NOMEMALLOC | GFP_NOWAIT,

in mm/damon/paddr.c also can be cleaned up to

.gfp_mask = (GFP_HIGHUSER_MOVABLE & ~__GFP_RECLAIM) |
                        | __GFP_NOMEMALLOC | GFP_NOWAIT, 

?

With or without that:

Reviewed-by: Harry Yoo <harry.yoo@...cle.com>

-- 
Cheers,
Harry / Hyeonggon

>  mm/filemap.c    | 2 +-
>  mm/mmu_gather.c | 4 ++--
>  mm/rmap.c       | 2 +-
>  mm/vmalloc.c    | 2 +-
>  4 files changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/mm/filemap.c b/mm/filemap.c
> index 4e5c9544fee4..c21e98657e0b 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -1961,7 +1961,7 @@ struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
>  			gfp &= ~__GFP_FS;
>  		if (fgp_flags & FGP_NOWAIT) {
>  			gfp &= ~GFP_KERNEL;
> -			gfp |= GFP_NOWAIT | __GFP_NOWARN;
> +			gfp |= GFP_NOWAIT;
>  		}
>  		if (WARN_ON_ONCE(!(fgp_flags & (FGP_LOCK | FGP_FOR_MMAP))))
>  			fgp_flags |= FGP_LOCK;
> diff --git a/mm/mmu_gather.c b/mm/mmu_gather.c
> index b49cc6385f1f..374aa6f021c6 100644
> --- a/mm/mmu_gather.c
> +++ b/mm/mmu_gather.c
> @@ -32,7 +32,7 @@ static bool tlb_next_batch(struct mmu_gather *tlb)
>  	if (tlb->batch_count == MAX_GATHER_BATCH_COUNT)
>  		return false;
>  
> -	batch = (void *)__get_free_page(GFP_NOWAIT | __GFP_NOWARN);
> +	batch = (void *)__get_free_page(GFP_NOWAIT);
>  	if (!batch)
>  		return false;
>  
> @@ -364,7 +364,7 @@ void tlb_remove_table(struct mmu_gather *tlb, void *table)
>  	struct mmu_table_batch **batch = &tlb->batch;
>  
>  	if (*batch == NULL) {
> -		*batch = (struct mmu_table_batch *)__get_free_page(GFP_NOWAIT | __GFP_NOWARN);
> +		*batch = (struct mmu_table_batch *)__get_free_page(GFP_NOWAIT);
>  		if (*batch == NULL) {
>  			tlb_table_invalidate(tlb);
>  			tlb_remove_table_one(table);
> diff --git a/mm/rmap.c b/mm/rmap.c
> index 568198e9efc2..7baa7385e1ce 100644
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
> @@ -285,7 +285,7 @@ int anon_vma_clone(struct vm_area_struct *dst, struct vm_area_struct *src)
>  	list_for_each_entry_reverse(pavc, &src->anon_vma_chain, same_vma) {
>  		struct anon_vma *anon_vma;
>  
> -		avc = anon_vma_chain_alloc(GFP_NOWAIT | __GFP_NOWARN);
> +		avc = anon_vma_chain_alloc(GFP_NOWAIT);
>  		if (unlikely(!avc)) {
>  			unlock_anon_vma_root(root);
>  			root = NULL;
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index 6dbcdceecae1..90c3de1a0417 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -5177,7 +5177,7 @@ static void vmap_init_nodes(void)
>  	int n = clamp_t(unsigned int, num_possible_cpus(), 1, 128);
>  
>  	if (n > 1) {
> -		vn = kmalloc_array(n, sizeof(*vn), GFP_NOWAIT | __GFP_NOWARN);
> +		vn = kmalloc_array(n, sizeof(*vn), GFP_NOWAIT);
>  		if (vn) {
>  			/* Node partition is 16 pages. */
>  			vmap_zone_size = (1 << 4) * PAGE_SIZE;
> -- 
> 2.34.1
>