From: Peter Xu <peterx@redhat.com>
To: linux-mm@kvack.org, linux-kernel@vger.kernel.org
Cc: Nadav Amit <nadav.amit@gmail.com>,
Miaohe Lin <linmiaohe@huawei.com>,
Mike Rapoport <rppt@linux.vnet.ibm.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Hugh Dickins <hughd@google.com>,
peterx@redhat.com, Jerome Glisse <jglisse@redhat.com>,
Mike Kravetz <mike.kravetz@oracle.com>,
Jason Gunthorpe <jgg@ziepe.ca>,
Matthew Wilcox <willy@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>,
Axel Rasmussen <axelrasmussen@google.com>,
"Kirill A . Shutemov" <kirill@shutemov.name>
Subject: [PATCH v2 08/24] mm: Introduce ZAP_FLAG_SKIP_SWAP
Date: Tue, 27 Apr 2021 12:13:01 -0400 [thread overview]
Message-ID: <20210427161317.50682-9-peterx@redhat.com> (raw)
In-Reply-To: <20210427161317.50682-1-peterx@redhat.com>
Firstly, the comment in zap_pte_range() is misleading because it checks against
details rather than check_mappings, so it's against what the code did.
Meanwhile, it's confusing too on not explaining why passing in the details
pointer would mean to skip all swap entries. New user of zap_details could
very possibly miss this fact if they don't read deep until zap_pte_range()
because there's no comment at zap_details talking about it at all, so swap
entries could be errornously skipped without being noticed.
This partly reverts 3e8715fdc03e ("mm: drop zap_details::check_swap_entries"),
but introduce ZAP_FLAG_SKIP_SWAP flag, which means the opposite of previous
"details" parameter: the caller should explicitly set this to skip swap
entries, otherwise swap entries will always be considered (which is still the
major case here).
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
include/linux/mm.h | 12 ++++++++++++
mm/memory.c | 8 +++++---
2 files changed, 17 insertions(+), 3 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 39c944bf7ed3a..2227e9107e53e 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1704,6 +1704,8 @@ extern void user_shm_unlock(size_t, struct user_struct *);
/* Whether to check page->mapping when zapping */
#define ZAP_FLAG_CHECK_MAPPING BIT(0)
+/* Whether to skip zapping swap entries */
+#define ZAP_FLAG_SKIP_SWAP BIT(1)
/*
* Parameter block passed down to zap_pte_range in exceptional cases.
@@ -1726,6 +1728,16 @@ zap_check_mapping_skip(struct zap_details *details, struct page *page)
return details->zap_mapping != page_rmapping(page);
}
+/* Return true if skip swap entries, false otherwise */
+static inline bool
+zap_skip_swap(struct zap_details *details)
+{
+ if (!details)
+ return false;
+
+ return details->zap_flags & ZAP_FLAG_SKIP_SWAP;
+}
+
struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
pte_t pte);
struct page *vm_normal_page_pmd(struct vm_area_struct *vma, unsigned long addr,
diff --git a/mm/memory.c b/mm/memory.c
index 94954436544f7..5325c1c2cbd78 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1284,8 +1284,7 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
continue;
}
- /* If details->check_mapping, we leave swap entries. */
- if (unlikely(details))
+ if (unlikely(zap_skip_swap(details)))
continue;
if (!non_swap_entry(entry))
@@ -3236,7 +3235,10 @@ void unmap_mapping_pages(struct address_space *mapping, pgoff_t start,
pgoff_t nr, bool even_cows)
{
pgoff_t first_index = start, last_index = start + nr - 1;
- struct zap_details details = { .zap_mapping = mapping };
+ struct zap_details details = {
+ .zap_mapping = mapping,
+ .zap_flags = ZAP_FLAG_SKIP_SWAP,
+ };
if (!even_cows)
details.zap_flags |= ZAP_FLAG_CHECK_MAPPING;
--
2.26.2
next prev parent reply other threads:[~2021-04-27 16:21 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-27 16:12 [PATCH v2 00/24] userfaultfd-wp: Support shmem and hugetlbfs Peter Xu
2021-04-27 16:12 ` [PATCH v2 01/24] shmem/userfaultfd: Take care of UFFDIO_COPY_MODE_WP Peter Xu
2021-04-27 16:12 ` [PATCH v2 02/24] mm: Clear vmf->pte after pte_unmap_same() returns Peter Xu
2021-04-27 16:12 ` [PATCH v2 03/24] mm/userfaultfd: Introduce special pte for unmapped file-backed mem Peter Xu
2021-04-27 16:12 ` [PATCH v2 04/24] mm/swap: Introduce the idea of special swap ptes Peter Xu
2021-04-27 16:12 ` [PATCH v2 05/24] shmem/userfaultfd: Handle uffd-wp special pte in page fault handler Peter Xu
2021-04-27 18:54 ` Peter Xu
2021-04-27 16:12 ` [PATCH v2 06/24] mm: Drop first_index/last_index in zap_details Peter Xu
2021-04-27 16:13 ` [PATCH v2 07/24] mm: Introduce zap_details.zap_flags Peter Xu
2021-04-27 16:13 ` Peter Xu [this message]
2021-04-27 16:13 ` [PATCH v2 09/24] mm: Pass zap_flags into unmap_mapping_pages() Peter Xu
2021-04-27 16:13 ` [PATCH v2 10/24] shmem/userfaultfd: Persist uffd-wp bit across zapping for file-backed Peter Xu
2021-04-27 16:13 ` [PATCH v2 11/24] shmem/userfaultfd: Allow wr-protect none pte for file-backed mem Peter Xu
2021-04-27 16:13 ` [PATCH v2 12/24] shmem/userfaultfd: Allows file-back mem to be uffd wr-protected on thps Peter Xu
2021-04-27 16:13 ` [PATCH v2 13/24] shmem/userfaultfd: Handle the left-overed special swap ptes Peter Xu
2021-04-27 16:13 ` [PATCH v2 14/24] shmem/userfaultfd: Pass over uffd-wp special swap pte when fork() Peter Xu
2021-04-27 16:13 ` [PATCH v2 15/24] mm/hugetlb: Drop __unmap_hugepage_range definition from hugetlb.h Peter Xu
2021-04-27 16:13 ` [PATCH v2 16/24] hugetlb/userfaultfd: Hook page faults for uffd write protection Peter Xu
2021-04-28 0:07 ` Peter Xu
2021-04-27 16:13 ` [PATCH v2 17/24] hugetlb/userfaultfd: Take care of UFFDIO_COPY_MODE_WP Peter Xu
2021-04-27 16:13 ` [PATCH v2 18/24] hugetlb/userfaultfd: Handle UFFDIO_WRITEPROTECT Peter Xu
2021-04-27 16:13 ` [PATCH v2 19/24] mm/hugetlb: Introduce huge version of special swap pte helpers Peter Xu
2021-04-27 16:13 ` [PATCH v2 20/24] hugetlb/userfaultfd: Handle uffd-wp special pte in hugetlb pf handler Peter Xu
2021-04-27 16:13 ` [PATCH v2 21/24] hugetlb/userfaultfd: Allow wr-protect none ptes Peter Xu
2021-04-27 16:13 ` [PATCH v2 22/24] hugetlb/userfaultfd: Only drop uffd-wp special pte if required Peter Xu
2021-04-27 16:13 ` [PATCH v2 23/24] mm/userfaultfd: Enable write protection for shmem & hugetlbfs Peter Xu
2021-04-27 16:13 ` [PATCH v2 24/24] userfaultfd/selftests: Enable uffd-wp for shmem/hugetlbfs Peter Xu
2021-05-12 19:00 ` [PATCH v2 00/24] userfaultfd-wp: Support shmem and hugetlbfs Peter Xu
2021-05-14 7:07 ` Hugh Dickins
2021-05-14 13:18 ` Peter Xu
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=20210427161317.50682-9-peterx@redhat.com \
--to=peterx@redhat.com \
--cc=aarcange@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=axelrasmussen@google.com \
--cc=hughd@google.com \
--cc=jgg@ziepe.ca \
--cc=jglisse@redhat.com \
--cc=kirill@shutemov.name \
--cc=linmiaohe@huawei.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mike.kravetz@oracle.com \
--cc=nadav.amit@gmail.com \
--cc=rppt@linux.vnet.ibm.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).