From: Peter Xu <peterx@redhat.com>
To: Mike Kravetz <mike.kravetz@oracle.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
linux-s390@vger.kernel.org, shu wang <malate_wangshu@hotmail.com>,
Axel Rasmussen <axelrasmussen@google.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Heiko Carstens <hca@linux.ibm.com>,
Alexey Dobriyan <adobriyan@gmail.com>,
Matthew Wilcox <willy@infradead.org>,
Michel Lespinasse <walken@google.com>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [RFC PATCH 4/5] hugetlb: don't permit pmd sharing if soft dirty in use
Date: Wed, 17 Feb 2021 14:44:36 -0500 [thread overview]
Message-ID: <20210217194436.GD6519@xz-x1> (raw)
In-Reply-To: <20210211000322.159437-5-mike.kravetz@oracle.com>
On Wed, Feb 10, 2021 at 04:03:21PM -0800, Mike Kravetz wrote:
> If page modifications are being monitoried with the soft dirty mechanism,
> then this information is contained in page table entries. Tracking is
> enabled on a 'per-process' basis. hugetlb pmd sharing allows processes
> to share page table entries. This makes pmd sharing incompatible with
> soft dirty monitoring. So, pmd sharing must be disabled if soft dirty
> tracking is in use.
>
> The VM_SOFTDIRTY flag is set in all vma's by default. When soft dirty
> monitoring is started, the flag is cleared. We can therefore allow pmd
> sharing in vmas with the VM_SOFTDIRTY flag set. Check this when deciding
> to perform pmd sharing.
>
> A subsequent patch will add code to allow soft dirty monitoring for hugetlb
> vmas. Any existing pmd sharing will be undone at that time.
>
> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
> ---
> mm/hugetlb.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index b561b6867ec1..cf4aa63be9b1 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -5285,6 +5285,13 @@ static bool vma_shareable(struct vm_area_struct *vma, unsigned long addr)
> unsigned long base = addr & PUD_MASK;
> unsigned long end = base + PUD_SIZE;
>
> + /*
> + * Do not allow pmd sharing if soft dirty tracking is in use.
> + */
> + if (IS_ENABLED(CONFIG_MEM_SOFT_DIRTY) &&
> + !(vma->vm_flags & VM_SOFTDIRTY))
> + return false;
> +
Reviewed-by: Peter Xu <peterx@redhat.com>
The indent of using three tabs is a bit weird to me, though.. I do see this
happen somewhere else in the repo too, so maybe it's a way to indent that I
don't know.
Thanks,
--
Peter Xu
next prev parent reply other threads:[~2021-02-17 19:47 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-11 0:03 [RFC PATCH 0/5] Add hugetlb soft dirty support Mike Kravetz
2021-02-11 0:03 ` [RFC PATCH 1/5] hugetlb: add hugetlb helpers for " Mike Kravetz
2021-02-17 16:24 ` Peter Xu
2021-02-18 22:58 ` Mike Kravetz
2021-02-24 16:46 ` Gerald Schaefer
2021-02-24 16:55 ` Gerald Schaefer
2021-02-11 0:03 ` [RFC PATCH 2/5] hugetlb: enhance hugetlb fault processing to support soft dirty Mike Kravetz
2021-02-17 19:32 ` Peter Xu
2021-02-18 23:26 ` Mike Kravetz
2021-02-11 0:03 ` [RFC PATCH 3/5] mm proc/task_mmu.c: add soft dirty pte checks for hugetlb Mike Kravetz
2021-02-17 19:35 ` Peter Xu
2021-02-18 23:59 ` Mike Kravetz
2021-02-11 0:03 ` [RFC PATCH 4/5] hugetlb: don't permit pmd sharing if soft dirty in use Mike Kravetz
2021-02-17 19:44 ` Peter Xu [this message]
2021-02-11 0:03 ` [RFC PATCH 5/5] mm proc/task_mmu.c: add hugetlb specific routine for clear_refs Mike Kravetz
2021-02-17 20:25 ` Peter Xu
2021-02-19 0:14 ` Mike Kravetz
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=20210217194436.GD6519@xz-x1 \
--to=peterx@redhat.com \
--cc=aarcange@redhat.com \
--cc=adobriyan@gmail.com \
--cc=akpm@linux-foundation.org \
--cc=axelrasmussen@google.com \
--cc=hca@linux.ibm.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=linux-s390@vger.kernel.org \
--cc=malate_wangshu@hotmail.com \
--cc=mike.kravetz@oracle.com \
--cc=walken@google.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;
as well as URLs for NNTP newsgroup(s).