Re: [RFC PATCH 03/15] mm/vmalloc: introduce new vrealloc() call and its subsidiary reach analog

[Roman Penyaev]

On 2019-01-09 17:50, Matthew Wilcox wrote:
> On Wed, Jan 09, 2019 at 05:40:13PM +0100, Roman Penyaev wrote:
> > Basically vrealloc() repeats glibc realloc() with only one big 
> > difference:
> > old area is not freed, i.e. caller is responsible for calling vfree() 
> > in
> > case of successfull reallocation.
>
> Ouch.  Don't call it the same thing when you're providing such 
> different
> semantics.  I agree with you that the new semantics are useful ones,
> I just want it called something else.  Maybe vcopy()?  vclone()?

vclone(). I like vclone().  But Linus does not like this reallocation
under the hood for epoll (where this vrealloc() should have been used),
so seems that won't be needed at all.

> > + *	Do not forget to call vfree() passing old address.  But careful,
> > + *	calling vfree() from interrupt will cause vfree_deferred() call,
> > + *	which in its turn uses freed address as a temporal pointer for a
>
> "temporary", not temporal.

Ha! Now I got the difference.  Thanks, Mathew :)

> > + *	llist element, i.e. memory will be corrupted.

--
Roman