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From: Peter Xu <peterx@redhat.com>
To: linux-kernel@vger.kernel.org,
	Andrew Morton <akpm@linux-foundation.org>,
	Hugh Dickins <hughd@google.com>,
	linux-mm@kvack.org
Cc: Andrea Arcangeli <aarcange@redhat.com>,
	Yang Shi <shy828301@gmail.com>,
	Matthew Wilcox <willy@infradead.org>,
	peterx@redhat.com, Jerome Glisse <jglisse@redhat.com>,
	Mike Rapoport <rppt@linux.vnet.ibm.com>,
	"Kirill A . Shutemov" <kirill@shutemov.name>,
	Miaohe Lin <linmiaohe@huawei.com>,
	David Hildenbrand <david@redhat.com>,
	Alistair Popple <apopple@nvidia.com>
Subject: [PATCH v2 0/5] mm: A few cleanup patches around zap, shmem and uffd
Date: Thu,  2 Sep 2021 16:17:16 -0400	[thread overview]
Message-ID: <20210902201721.52796-1-peterx@redhat.com> (raw)

[Based on tag v5.14, but it should still apply to -mm too.  If not, I can
 repost anytime]

Hugh,

So I found one thing that I feel like a bug of commit 22061a1ffabdb9c3, but I'm
not sure.  If that's the case, patch 5 of this series may be the fix for it.

The problem is unmap_mapping_page() in current tree is calling
unmap_mapping_range_tree() with a details pointer, while by default when detail
pointer is specified, it means "we want to skip zapping swap entries".

I didn't mention this in v1 simply because I thought it was fine, e.g., swap
entry won't be kept in shmem ptes so skipped is okay (it is never okay with
shmem uffd-wp but uffd-wp code is not landed yet).  However I just remembered
there could also be e.g. shmem migration entries if I'm not wrong.  From that
pov, skipping swap entries for unmap_mapping_page() seems wrong.  Would you
please help check?

It'll be great if you can comment on patch 1 too, to see whether that's okay
and what I could have been missing there (e.g., if you have other concern on
breaking stuff, I'll be happy to test).

v2:
- Patch "mm: Clear vmf->pte after pte_unmap_same() returns"
  - Remove one comment [David]
- Collect r-b for patch 2/3
- Rewrite the last two patches to drop ZAP_FLAG_CHECK_MAPPING, dropping
  Alistair's r-b on patch 5 because it changed [David, Matthew]

===== v1 cover letter =====

I picked up these patches from uffd-wp v5 series here:

https://lore.kernel.org/lkml/20210715201422.211004-1-peterx@redhat.com/

IMHO all of them are very nice cleanups to existing code already, they're all
small and self-contained.  They'll be needed by uffd-wp coming series.  I would
appreciate if they can be accepted earlier, so as to not carry them over always
with the uffd-wp series.

I removed some CC from the uffd-wp v5 series to reduce the noise, and added a
few more into it.

Reviews are greatly welcomed, thanks.

Peter Xu (5):
  mm/shmem: Unconditionally set pte dirty in mfill_atomic_install_pte
  mm: Clear vmf->pte after pte_unmap_same() returns
  mm: Drop first_index/last_index in zap_details
  mm: Add zap_skip_check_mapping() helper
  mm: Add ZAP_FLAG_SKIP_SWAP and zap_flags

 include/linux/mm.h | 33 ++++++++++++++++++--
 mm/memory.c        | 76 +++++++++++++++++++---------------------------
 mm/shmem.c         |  1 -
 mm/userfaultfd.c   |  3 +-
 4 files changed, 62 insertions(+), 51 deletions(-)

-- 
2.31.1


             reply	other threads:[~2021-09-02 20:17 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-02 20:17 Peter Xu [this message]
2021-09-02 20:17 ` [PATCH v2 1/5] mm/shmem: Unconditionally set pte dirty in mfill_atomic_install_pte Peter Xu
2021-09-03  7:42   ` David Hildenbrand
2021-09-03 20:00     ` Peter Xu
2021-09-03 20:02       ` David Hildenbrand
2021-09-02 20:17 ` [PATCH v2 2/5] mm: Clear vmf->pte after pte_unmap_same() returns Peter Xu
2021-09-08  1:12   ` Liam Howlett
2021-09-02 20:17 ` [PATCH v2 3/5] mm: Drop first_index/last_index in zap_details Peter Xu
2021-09-02 20:18 ` [PATCH v2 4/5] mm: Add zap_skip_check_mapping() helper Peter Xu
2021-09-03  0:58   ` Alistair Popple
2021-09-03  1:39     ` Peter Xu
2021-09-03  1:50       ` Alistair Popple
2021-09-03  7:07         ` David Hildenbrand
2021-09-02 20:18 ` [PATCH v2 5/5] mm: Add ZAP_FLAG_SKIP_SWAP and zap_flags Peter Xu
2021-09-03  7:25   ` David Hildenbrand
2021-09-03  7:31     ` David Hildenbrand
2021-09-08  0:43     ` Peter Xu
2021-09-08  0:35 ` [PATCH v2 0/5] mm: A few cleanup patches around zap, shmem and uffd Peter Xu

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