From: Andrea Arcangeli <aarcange@redhat.com>
To: Hugh Dickins <hughd@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>, linux-mm@kvack.org
Subject: Re: [PATCH mmotm] thp: transparent hugepage core fixlet
Date: Tue, 11 Jan 2011 02:57:42 +0100 [thread overview]
Message-ID: <20110111015742.GL9506@random.random> (raw)
In-Reply-To: <alpine.LSU.2.00.1101101652200.11559@sister.anvils>
Hi Hugh,
On Mon, Jan 10, 2011 at 04:55:53PM -0800, Hugh Dickins wrote:
> If you configure THP in addition to HUGETLB_PAGE on x86_32 without PAE,
> the p?d-folding works out that munlock_vma_pages_range() can crash to
> follow_page()'s pud_huge() BUG_ON(flags & FOLL_GET): it needs the same
> VM_HUGETLB check already there on the pmd_huge() line. Conveniently,
> openSUSE provides a "blogd" which tests this out at startup!
>
> Signed-off-by: Hugh Dickins <hughd@google.com>
> ---
> This massive rework belongs just after thp-transparent-hugepage-core.patch
>
> mm/memory.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> --- mmotm.orig/mm/memory.c 2011-01-10 16:31:29.000000000 -0800
> +++ mmotm/mm/memory.c 2011-01-10 16:33:16.000000000 -0800
> @@ -1288,7 +1288,7 @@ struct page *follow_page(struct vm_area_
> pud = pud_offset(pgd, address);
> if (pud_none(*pud))
> goto no_page_table;
> - if (pud_huge(*pud)) {
> + if (pud_huge(*pud) && vma->vm_flags & VM_HUGETLB) {
> BUG_ON(flags & FOLL_GET);
> page = follow_huge_pud(mm, address, pud, flags & FOLL_WRITE);
> goto out;
How is THP related to this? pud_trans_huge doesn't exist, if pud_huge
is true, vma is already guaranteed to belong to hugetlbfs without
requiring the additional check.
I added the check to pmd_huge already, there it is needed, but for
pud_huge it isn't as far as I can tell.
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Fight unfair telecom policy in Canada: sign http://dissolvethecrtc.ca/
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2011-01-11 1:57 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-01-11 0:55 [PATCH mmotm] thp: transparent hugepage core fixlet Hugh Dickins
2011-01-11 1:57 ` Andrea Arcangeli [this message]
2011-01-11 2:29 ` Hugh Dickins
2011-01-11 14:04 ` Andrea Arcangeli
2011-01-11 16:31 ` Andrea Arcangeli
2011-01-11 22:59 ` Hugh Dickins
2011-01-12 2:02 ` Andrea Arcangeli
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=20110111015742.GL9506@random.random \
--to=aarcange@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=hughd@google.com \
--cc=linux-mm@kvack.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.