Linux-mm Archive on lore.kernel.org
 help / color / Atom feed
From: Wei Yang <richardw.yang@linux.intel.com>
To: akpm@linux-foundation.org
Cc: kirill.shutemov@linux.intel.com, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org,
	Wei Yang <richardw.yang@linux.intel.com>
Subject: [PATCH 2/2] mm/page_vma_mapped: page table boundary is already guaranteed
Date: Thu, 28 Nov 2019 09:03:21 +0800
Message-ID: <20191128010321.21730-2-richardw.yang@linux.intel.com> (raw)
In-Reply-To: <20191128010321.21730-1-richardw.yang@linux.intel.com>

The check here is to guarantee pvmw->address iteration is limited in one
page table boundary. To be specific, here the address range should be in
one PMD_SIZE.

If my understanding is correct, this check is already done in the above
check:

    address >= __vma_address(page, vma) + PMD_SIZE

The boundary check here seems not necessary.

Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>

---
Test:
   more than 48 hours kernel build test shows this code is not touched.
---
 mm/page_vma_mapped.c | 13 +------------
 1 file changed, 1 insertion(+), 12 deletions(-)

diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c
index 76e03650a3ab..25aada8a1271 100644
--- a/mm/page_vma_mapped.c
+++ b/mm/page_vma_mapped.c
@@ -163,7 +163,6 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
 			return not_found(pvmw);
 		return true;
 	}
-restart:
 	pgd = pgd_offset(mm, pvmw->address);
 	if (!pgd_present(*pgd))
 		return false;
@@ -225,17 +224,7 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
 					__vma_address(pvmw->page, pvmw->vma) +
 					PMD_SIZE)
 				return not_found(pvmw);
-			/* Did we cross page table boundary? */
-			if (pvmw->address % PMD_SIZE == 0) {
-				pte_unmap(pvmw->pte);
-				if (pvmw->ptl) {
-					spin_unlock(pvmw->ptl);
-					pvmw->ptl = NULL;
-				}
-				goto restart;
-			} else {
-				pvmw->pte++;
-			}
+			pvmw->pte++;
 		} while (pte_none(*pvmw->pte));
 
 		if (!pvmw->ptl) {
-- 
2.17.1



  reply index

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-28  1:03 [PATCH 1/2] mm/page_vma_mapped: use PMD_SIZE instead of calculating it Wei Yang
2019-11-28  1:03 ` Wei Yang [this message]
2019-11-28  8:31   ` [PATCH 2/2] mm/page_vma_mapped: page table boundary is already guaranteed Kirill A. Shutemov
2019-11-28 21:09     ` Wei Yang
2019-11-28 22:39       ` Matthew Wilcox
2019-11-29  8:30         ` Wei Yang
2019-11-29 11:18           ` Matthew Wilcox
2019-12-02  6:53             ` Wei Yang
2019-11-28  8:32 ` [PATCH 1/2] mm/page_vma_mapped: use PMD_SIZE instead of calculating it Kirill A. Shutemov
2019-11-28 21:22   ` Wei Yang
2019-12-02  8:03     ` Kirill A. Shutemov
2019-12-02  8:54       ` Wei Yang
2019-12-02 22:21       ` Wei Yang
2019-12-03  9:47         ` Kirill A. Shutemov
2019-12-03 15:14           ` Wei Yang

Reply instructions:

You may reply publically 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=20191128010321.21730-2-richardw.yang@linux.intel.com \
    --to=richardw.yang@linux.intel.com \
    --cc=akpm@linux-foundation.org \
    --cc=kirill.shutemov@linux.intel.com \
    --cc=linux-kernel@vger.kernel.org \
    --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

Linux-mm Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-mm/0 linux-mm/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-mm linux-mm/ https://lore.kernel.org/linux-mm \
		linux-mm@kvack.org
	public-inbox-index linux-mm

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kvack.linux-mm


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git