From: Alexander H Duyck <alexander.duyck@gmail.com>
To: Yunsheng Lin <linyunsheng@huawei.com>
Cc: davem@davemloft.net, kuba@kernel.org, pabeni@redhat.com,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org
Subject: Re: [RFC v11 08/14] mm: page_frag: some minor refactoring before adding new API
Date: Wed, 31 Jul 2024 10:02:22 -0700 [thread overview]
Message-ID: <17ae2088c08d34a17db8eeb1fa2821d686198a5b.camel@gmail.com> (raw)
In-Reply-To: <e532356e-3153-4132-9d20-940bc3b84ef3@huawei.com>
On Wed, 2024-07-31 at 20:35 +0800, Yunsheng Lin wrote:
> On 2024/7/30 23:12, Alexander H Duyck wrote:
>
> ...
>
> > > }
> > >
> > > nc->pagecnt_bias--;
> > > nc->remaining = remaining - fragsz;
> > >
> > > return encoded_page_address(encoded_va) +
> > > (page_frag_cache_page_size(encoded_va) - remaining);
> >
> > Parenthesis here shouldn't be needed, addition and subtractions
> > operations can happen in any order with the result coming out the same.
>
> I am playing safe to avoid overflow here, as I am not sure if the allocator
> will give us the last page. For example, '0xfffffffffffff000 + 0x1000' will
> have a overflow.
So what if it does though? When you subtract remaining it will
underflow and go back to the correct value shouldn't it?
next prev parent reply other threads:[~2024-07-31 17:02 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20240719093338.55117-1-linyunsheng@huawei.com>
2024-07-19 9:33 ` [RFC v11 01/14] mm: page_frag: add a test module for page_frag Yunsheng Lin
2024-07-21 17:34 ` Alexander Duyck
2024-07-23 13:19 ` Yunsheng Lin
2024-07-19 9:33 ` [RFC v11 02/14] mm: move the page fragment allocator from page_alloc into its own file Yunsheng Lin
2024-07-21 17:58 ` Alexander Duyck
2024-07-27 15:04 ` Yunsheng Lin
2024-07-19 9:33 ` [RFC v11 03/14] mm: page_frag: use initial zero offset for page_frag_alloc_align() Yunsheng Lin
2024-07-21 18:34 ` Alexander Duyck
2024-07-19 9:33 ` [RFC v11 04/14] mm: page_frag: add '_va' suffix to page_frag API Yunsheng Lin
[not found] ` <CAKgT0UcqELiXntRA_uD8eJGjt-OCLO64ax=YFXrCHNnaj9kD8g@mail.gmail.com>
2024-07-25 12:21 ` Yunsheng Lin
2024-07-19 9:33 ` [RFC v11 05/14] mm: page_frag: avoid caller accessing 'page_frag_cache' directly Yunsheng Lin
2024-07-21 23:01 ` Alexander H Duyck
2024-07-19 9:33 ` [RFC v11 07/14] mm: page_frag: reuse existing space for 'size' and 'pfmemalloc' Yunsheng Lin
2024-07-21 22:59 ` Alexander H Duyck
2024-07-19 9:33 ` [RFC v11 08/14] mm: page_frag: some minor refactoring before adding new API Yunsheng Lin
2024-07-21 23:40 ` Alexander H Duyck
2024-07-22 12:55 ` Yunsheng Lin
2024-07-22 15:32 ` Alexander Duyck
2024-07-23 13:19 ` Yunsheng Lin
2024-07-30 13:20 ` Yunsheng Lin
2024-07-30 15:12 ` Alexander H Duyck
2024-07-31 12:35 ` Yunsheng Lin
2024-07-31 17:02 ` Alexander H Duyck [this message]
2024-08-01 12:53 ` Yunsheng Lin
2024-07-19 9:33 ` [RFC v11 09/14] mm: page_frag: use __alloc_pages() to replace alloc_pages_node() Yunsheng Lin
2024-07-21 21:41 ` Alexander H Duyck
2024-07-24 12:54 ` Yunsheng Lin
2024-07-24 15:03 ` Alexander Duyck
2024-07-25 12:19 ` Yunsheng Lin
2024-08-14 18:34 ` Alexander H Duyck
2024-07-19 9:33 ` [RFC v11 11/14] mm: page_frag: introduce prepare/probe/commit API Yunsheng Lin
2024-07-19 9:33 ` [RFC v11 13/14] mm: page_frag: update documentation for page_frag Yunsheng Lin
[not found] ` <CAKgT0UcGvrS7=r0OCGZipzBv8RuwYtRwb2QDXqiF4qW5CNws4g@mail.gmail.com>
[not found] ` <b2001dba-a2d2-4b49-bc9f-59e175e7bba1@huawei.com>
2024-07-22 15:21 ` [RFC v11 00/14] Replace page_frag with page_frag_cache for sk_page_frag() Alexander Duyck
2024-07-23 13:17 ` Yunsheng Lin
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