From: Christoph Hellwig <hch@lst.de>
To: Huan Yang <link@vivo.com>
Cc: bingbu.cao@linux.intel.com,
"Matthew Wilcox" <willy@infradead.org>,
"Christoph Hellwig" <hch@lst.de>,
"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, "Muchun Song" <muchun.song@linux.dev>
Subject: CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP is broken, was Re: [RFC PATCH 0/6] Deep talk about folio vmap
Date: Fri, 4 Apr 2025 11:01:11 +0200 [thread overview]
Message-ID: <20250404090111.GB11105@lst.de> (raw)
In-Reply-To: <20250327092922.536-1-link@vivo.com>
After the btrfs compressed bio discussion I think the hugetlb changes that
skip the tail pages are fundamentally unsafe in the current kernel.
That is because the bio_vec representation assumes tail pages do exist, so
as soon as you are doing direct I/O that generates a bvec starting beyond
the present head page things will blow up. Other users of bio_vecs might
do the same, but the way the block bio_vecs are generated are very suspect
to that. So we'll first need to sort that out and a few other things
before we can even think of enabling such a feature.
next prev parent reply other threads:[~2025-04-04 9:01 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-03-27 9:28 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 ` Christoph Hellwig [this message]
2025-04-04 9:38 ` CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP is broken, was " 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
2025-04-07 9:48 ` Muchun Song
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20250404090111.GB11105@lst.de \
--to=hch@lst.de \
--cc=akpm@linux-foundation.org \
--cc=bingbu.cao@linux.intel.com \
--cc=christian.koenig@amd.com \
--cc=dri-devel@lists.freedesktop.org \
--cc=kraxel@redhat.com \
--cc=linaro-mm-sig@lists.linaro.org \
--cc=link@vivo.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-kselftest@vger.kernel.org \
--cc=linux-media@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=muchun.song@linux.dev \
--cc=opensource.kernel@vivo.com \
--cc=shuah@kernel.org \
--cc=sumit.semwal@linaro.org \
--cc=urezki@gmail.com \
--cc=vivek.kasireddy@intel.com \
--cc=willy@infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox