Re: [PATCH] mm: Drop INT_MAX limit from kvmalloc()

[Vlastimil Babka <vbabka@suse.cz>]

On 10/20/24 20:53, Kent Overstreet wrote:
> On Sun, Oct 20, 2024 at 11:46:11AM -0700, Linus Torvalds wrote:
>> On Sun, 20 Oct 2024 at 10:04, Kent Overstreet <kent.overstreet@linux.dev> wrote:
>> >
>> > But given that vmalloc() already supports > INT_MAX requests, and memory
>> > sizes keep growing so 2GB is getting pretty small - I think it's time,
>> > this is going to come up in other places sooner or later.
>> 
>> No.
>> 
>> If you need 2GB+ memory for filesystem operations, you fix your code.
> 
> This is for journal replay, where we've got a big array of keys and we
> need to sort them.
> 
> The keys have to fit in memory (and had to fit in memory previously, for
> them to be dirty in the journal);

What if the disk is moved to a smaller system, should the fs still mount
there? (I don't mean such a small system that it can't vmalloc() 2GB
specifically, but in principle...)

> this array is just _references_ to
> those keys.
> 
>> 2GB is more than you *can* allocate on 32-bit platforms, and even on
>> 64-bit ones it is often quite a lot.
> 
> This came up on a machine with 128GB of ram.