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

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Message-ID: <20190109165009.GM6310@bombadil.infradead.org>
Date:   Wed, 9 Jan 2019 08:50:09 -0800
From:   Matthew Wilcox <willy@...radead.org>
To:     Roman Penyaev <rpenyaev@...e.de>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...e.com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Joe Perches <joe@...ches.com>,
        "Luis R. Rodriguez" <mcgrof@...nel.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 03/15] mm/vmalloc: introduce new vrealloc() call and
 its subsidiary reach analog

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()?

> + *	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.

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