linux-kernel - Re: [PATCH v13 2/4] mm/slub: allow to set node and align in k[v]realloc

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Message-ID: <07d3689c-185e-496e-a0b8-53bb3194f0da@suse.cz>
Date: Tue, 15 Jul 2025 17:34:20 +0200
From: Vlastimil Babka <vbabka@...e.cz>
To: Danilo Krummrich <dakr@...nel.org>, Vitaly Wool
 <vitaly.wool@...sulko.se>, Linus Torvalds <torvalds@...ux-foundation.org>
Cc: linux-mm@...ck.org, akpm@...ux-foundation.org,
 linux-kernel@...r.kernel.org, Uladzislau Rezki <urezki@...il.com>,
 Alice Ryhl <aliceryhl@...gle.com>, rust-for-linux@...r.kernel.org,
 Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
 "Liam R . Howlett" <Liam.Howlett@...cle.com>,
 linux-bcachefs@...r.kernel.org, bpf@...r.kernel.org,
 Herbert Xu <herbert@...dor.apana.org.au>, Jann Horn <jannh@...gle.com>,
 Pedro Falcato <pfalcato@...e.de>, Kent Overstreet <kent.overstreet@...ux.dev>
Subject: Re: [PATCH v13 2/4] mm/slub: allow to set node and align in
 k[v]realloc

On 7/15/25 16:33, Danilo Krummrich wrote:
> On Tue Jul 15, 2025 at 3:58 PM CEST, Vitaly Wool wrote:
>> diff --git a/fs/bcachefs/darray.c b/fs/bcachefs/darray.c
>> index e86d36d23e9e..928e83a1ce42 100644
>> --- a/fs/bcachefs/darray.c
>> +++ b/fs/bcachefs/darray.c
>> @@ -21,7 +21,7 @@ int __bch2_darray_resize_noprof(darray_char *d, size_t element_size, size_t new_
>>  			return -ENOMEM;
>>  
>>  		void *data = likely(bytes < INT_MAX)
>> -			? kvmalloc_noprof(bytes, gfp)
>> +			? kvmalloc_node_align_noprof(bytes, 1, gfp, NUMA_NO_NODE)
>>  			: vmalloc_noprof(bytes);
>>  		if (!data)
>>  			return -ENOMEM;
>> diff --git a/fs/bcachefs/util.h b/fs/bcachefs/util.h
>> index 0a4b1d433621..2d6d4b547db8 100644
>> --- a/fs/bcachefs/util.h
>> +++ b/fs/bcachefs/util.h
>> @@ -61,7 +61,7 @@ static inline void *bch2_kvmalloc_noprof(size_t n, gfp_t flags)
>>  {
>>  	void *p = unlikely(n >= INT_MAX)
>>  		? vmalloc_noprof(n)
>> -		: kvmalloc_noprof(n, flags & ~__GFP_ZERO);
>> +		: kvmalloc_node_align_noprof(n, 1, flags & ~__GFP_ZERO, NUMA_NO_NODE);
>>  	if (p && (flags & __GFP_ZERO))
>>  		memset(p, 0, n);
>>  	return p;
> 
> I assume this is because kvmalloc(), and hence kvrealloc(), does this:
> 
> 	/* Don't even allow crazy sizes */
> 	if (unlikely(size > INT_MAX)) {
> 		WARN_ON_ONCE(!(flags & __GFP_NOWARN));
> 		return NULL;
> 	}
> 
> Do we still consider this a "crazy size"? :)

Yeah, with "we" including Linus:
https://lore.kernel.org/all/CAHk-=wi=PrbZnwnvhKEF6UUQNCZdNsUbr+hk-jOWGr-q4Mmz=Q@mail.gmail.com/