From: David Hildenbrand <david@redhat.com>
To: linux-kernel@vger.kernel.org
Cc: Andrew Morton <akpm@linux-foundation.org>,
Hugh Dickins <hughd@google.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
David Rientjes <rientjes@google.com>,
Shakeel Butt <shakeelb@google.com>,
John Hubbard <jhubbard@nvidia.com>,
Jason Gunthorpe <jgg@nvidia.com>,
Mike Kravetz <mike.kravetz@oracle.com>,
Mike Rapoport <rppt@linux.ibm.com>,
Yang Shi <shy828301@gmail.com>,
"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
Matthew Wilcox <willy@infradead.org>,
Vlastimil Babka <vbabka@suse.cz>, Jann Horn <jannh@google.com>,
Michal Hocko <mhocko@kernel.org>, Nadav Amit <namit@vmware.com>,
Rik van Riel <riel@surriel.com>, Roman Gushchin <guro@fb.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Peter Xu <peterx@redhat.com>, Donald Dutile <ddutile@redhat.com>,
Christoph Hellwig <hch@lst.de>, Oleg Nesterov <oleg@redhat.com>,
Jan Kara <jack@suse.cz>, Liang Zhang <zhangliang5@huawei.com>,
Pedro Gomes <pedrodemargomes@gmail.com>,
Oded Gabbay <oded.gabbay@gmail.com>,
linux-mm@kvack.org, David Hildenbrand <david@redhat.com>
Subject: [PATCH v1 02/15] mm/hugetlb: take src_mm->write_protect_seq in copy_hugetlb_page_range()
Date: Tue, 8 Mar 2022 15:14:24 +0100 [thread overview]
Message-ID: <20220308141437.144919-3-david@redhat.com> (raw)
In-Reply-To: <20220308141437.144919-1-david@redhat.com>
Let's do it just like copy_page_range(), taking the seqlock and making
sure the mmap_lock is held in write mode.
This allows for add a VM_BUG_ON to page_needs_cow_for_dma() and
properly synchronizes cocnurrent fork() with GUP-fast of hugetlb pages,
which will be relevant for further changes.
Signed-off-by: David Hildenbrand <david@redhat.com>
---
include/linux/mm.h | 4 ++++
mm/hugetlb.c | 8 ++++++--
2 files changed, 10 insertions(+), 2 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 9530f950f156..391b950e919d 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1323,6 +1323,8 @@ static inline bool is_cow_mapping(vm_flags_t flags)
/*
* This should most likely only be called during fork() to see whether we
* should break the cow immediately for a page on the src mm.
+ *
+ * The caller has to hold the PT lock and the vma->vm_mm->->write_protect_seq.
*/
static inline bool page_needs_cow_for_dma(struct vm_area_struct *vma,
struct page *page)
@@ -1330,6 +1332,8 @@ static inline bool page_needs_cow_for_dma(struct vm_area_struct *vma,
if (!is_cow_mapping(vma->vm_flags))
return false;
+ VM_BUG_ON(!(raw_read_seqcount(&vma->vm_mm->write_protect_seq) & 1));
+
if (!test_bit(MMF_HAS_PINNED, &vma->vm_mm->flags))
return false;
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index f294db835f4b..d3ce89697855 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -4710,6 +4710,8 @@ int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
vma->vm_start,
vma->vm_end);
mmu_notifier_invalidate_range_start(&range);
+ mmap_assert_write_locked(src);
+ raw_write_seqcount_begin(&src->write_protect_seq);
} else {
/*
* For shared mappings i_mmap_rwsem must be held to call
@@ -4842,10 +4844,12 @@ int copy_hugetlb_page_range(struct mm_struct *dst, struct mm_struct *src,
spin_unlock(dst_ptl);
}
- if (cow)
+ if (cow) {
+ raw_write_seqcount_end(&src->write_protect_seq);
mmu_notifier_invalidate_range_end(&range);
- else
+ } else {
i_mmap_unlock_read(mapping);
+ }
return ret;
}
--
2.35.1
next prev parent reply other threads:[~2022-03-08 14:16 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-08 14:14 [PATCH v1 00/15] mm: COW fixes part 2: reliable GUP pins of anonymous pages David Hildenbrand
2022-03-08 14:14 ` [PATCH v1 01/15] mm/rmap: fix missing swap_free() in try_to_unmap() after arch_unmap_one() failed David Hildenbrand
2022-03-08 14:14 ` David Hildenbrand [this message]
2022-03-08 14:14 ` [PATCH v1 03/15] mm/memory: slightly simplify copy_present_pte() David Hildenbrand
2022-03-08 14:14 ` [PATCH v1 04/15] mm/rmap: split page_dup_rmap() into page_dup_file_rmap() and page_try_dup_anon_rmap() David Hildenbrand
2022-03-08 14:14 ` [PATCH v1 05/15] mm/rmap: convert RMAP flags to a proper distinct rmap_t type David Hildenbrand
2022-03-08 17:15 ` Nadav Amit
2022-03-08 17:30 ` David Hildenbrand
2022-03-08 18:09 ` Linus Torvalds
2022-03-08 18:24 ` Nadav Amit
2022-03-08 18:42 ` Linus Torvalds
2022-03-08 14:14 ` [PATCH v1 06/15] mm/rmap: remove do_page_add_anon_rmap() David Hildenbrand
2022-03-08 14:14 ` [PATCH v1 07/15] mm/rmap: pass rmap flags to hugepage_add_anon_rmap() David Hildenbrand
2022-03-08 14:14 ` [PATCH v1 08/15] mm/rmap: drop "compound" parameter from page_add_new_anon_rmap() David Hildenbrand
2022-03-08 14:14 ` [PATCH v1 09/15] mm/rmap: use page_move_anon_rmap() when reusing a mapped PageAnon() page exclusively David Hildenbrand
2022-03-08 14:14 ` [PATCH v1 10/15] mm/page-flags: reuse PG_slab as PG_anon_exclusive for PageAnon() pages David Hildenbrand
2022-03-09 15:47 ` Matthew Wilcox
2022-03-09 16:57 ` David Hildenbrand
2022-03-09 17:40 ` Matthew Wilcox
2022-03-09 18:00 ` David Hildenbrand
2022-03-11 18:46 ` David Hildenbrand
2022-03-11 19:22 ` Linus Torvalds
2022-03-11 19:36 ` David Hildenbrand
2022-03-11 19:49 ` Linus Torvalds
2022-03-11 21:11 ` Matthew Wilcox
2022-03-12 8:11 ` David Hildenbrand
2022-03-11 21:02 ` Matthew Wilcox
2022-03-12 8:26 ` David Hildenbrand
2022-03-08 14:14 ` [PATCH v1 11/15] mm: remember exclusively mapped anonymous pages with PG_anon_exclusive David Hildenbrand
2022-03-11 18:52 ` David Hildenbrand
2022-03-08 14:14 ` [PATCH v1 12/15] mm/gup: disallow follow_page(FOLL_PIN) David Hildenbrand
2022-03-08 14:14 ` [PATCH v1 13/15] mm: support GUP-triggered unsharing of anonymous pages David Hildenbrand
2022-03-08 14:14 ` [PATCH v1 14/15] mm/gup: trigger FAULT_FLAG_UNSHARE when R/O-pinning a possibly shared anonymous page David Hildenbrand
2022-03-08 14:14 ` [PATCH v1 15/15] mm/gup: sanity-check with CONFIG_DEBUG_VM that anonymous pages are exclusive when (un)pinning David Hildenbrand
2022-03-08 14:19 ` [PATCH v1 00/15] mm: COW fixes part 2: reliable GUP pins of anonymous pages David Hildenbrand
2022-03-08 21:22 ` Linus Torvalds
2022-03-09 8:00 ` David Hildenbrand
2022-03-10 11:13 ` Oded Gabbay
2022-03-10 11:57 ` David Hildenbrand
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=20220308141437.144919-3-david@redhat.com \
--to=david@redhat.com \
--cc=aarcange@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=ddutile@redhat.com \
--cc=guro@fb.com \
--cc=hch@lst.de \
--cc=hughd@google.com \
--cc=jack@suse.cz \
--cc=jannh@google.com \
--cc=jgg@nvidia.com \
--cc=jhubbard@nvidia.com \
--cc=kirill.shutemov@linux.intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mhocko@kernel.org \
--cc=mike.kravetz@oracle.com \
--cc=namit@vmware.com \
--cc=oded.gabbay@gmail.com \
--cc=oleg@redhat.com \
--cc=pedrodemargomes@gmail.com \
--cc=peterx@redhat.com \
--cc=riel@surriel.com \
--cc=rientjes@google.com \
--cc=rppt@linux.ibm.com \
--cc=shakeelb@google.com \
--cc=shy828301@gmail.com \
--cc=torvalds@linux-foundation.org \
--cc=vbabka@suse.cz \
--cc=willy@infradead.org \
--cc=zhangliang5@huawei.com \
/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).