From: Christoph Hellwig <hch@lst.de>
To: Muchun Song <muchun.song@linux.dev>
Cc: "Huan Yang" <link@vivo.com>,
bingbu.cao@linux.intel.com, "Christoph Hellwig" <hch@lst.de>,
"Matthew Wilcox" <willy@infradead.org>,
"Gerd Hoffmann" <kraxel@redhat.com>,
"Vivek Kasireddy" <vivek.kasireddy@intel.com>,
"Sumit Semwal" <sumit.semwal@linaro.org>,
"Christian König" <christian.koenig@amd.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Uladzislau Rezki" <urezki@gmail.com>,
"Shuah Khan" <shuah@kernel.org>,
linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org,
linux-mm@kvack.org, linux-kselftest@vger.kernel.org,
opensource.kernel@vivo.com
Subject: Re: CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP is broken, was Re: [RFC PATCH 0/6] Deep talk about folio vmap
Date: Mon, 7 Apr 2025 10:59:44 +0200 [thread overview]
Message-ID: <20250407085943.GA27481@lst.de> (raw)
In-Reply-To: <35D26C00-952F-481C-8345-E339F0ED770B@linux.dev>
On Mon, Apr 07, 2025 at 02:43:20PM +0800, Muchun Song wrote:
> By the way, in case you truly struggle to comprehend the fundamental
> aspects of HVO, I would like to summarize for you the user-visible
> behaviors in comparison to the situation where HVO is disabled.
>
> HVO Status Tail Page Structures Head Page Structures
> Enabled Read-Only (RO) Read-Write (RW)
> Disabled Read-Write (RW) Read-Write (RW)
>
> The sole distinction between the two scenarios lies in whether the
> tail page structures are allowed to be written or not. Please refrain
> from getting bogged down in the details of the implementation of HVO.
This feels extremely fragile to me. I doubt many people know what
operations needs read vs write access to tail pages. Or for higher
level operations if needs access to tail pages at all.
next prev parent reply other threads:[~2025-04-07 8:59 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-03-27 9:28 [RFC PATCH 0/6] Deep talk about folio vmap Huan Yang
2025-03-27 9:28 ` [RFC PATCH 1/6] udmabuf: try fix udmabuf vmap Huan Yang
2025-03-27 9:28 ` [RFC PATCH 2/6] udmabuf: try udmabuf vmap test Huan Yang
2025-03-27 9:28 ` [RFC PATCH 3/6] mm/vmalloc: try add vmap folios range Huan Yang
2025-03-27 9:28 ` [RFC PATCH 4/6] udmabuf: use vmap_range_folios Huan Yang
2025-03-27 9:28 ` [RFC PATCH 5/6] udmabuf: vmap test suit for pages and pfns compare Huan Yang
2025-03-27 9:28 ` [RFC PATCH 6/6] udmabuf: remove no need code Huan Yang
2025-03-28 21:09 ` [RFC PATCH 0/6] Deep talk about folio vmap Vishal Moola (Oracle)
2025-04-04 9:01 ` CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP is broken, was " Christoph Hellwig
2025-04-04 9:38 ` Muchun Song
2025-04-04 10:07 ` Muchun Song
2025-04-07 1:59 ` Huan Yang
2025-04-07 2:57 ` Muchun Song
2025-04-07 3:21 ` Huan Yang
2025-04-07 3:37 ` Muchun Song
2025-04-07 6:43 ` Muchun Song
2025-04-07 7:09 ` Huan Yang
2025-04-07 7:22 ` Muchun Song
2025-04-07 8:55 ` Huan Yang
2025-04-07 8:59 ` Christoph Hellwig [this message]
2025-04-07 9:48 ` Muchun Song
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