From: Peter Xu <peterx@redhat.com>
To: Axel Rasmussen <axelrasmussen@google.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>,
Andrea Arcangeli <aarcange@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
Daniel Colascione <dancol@google.com>,
Hugh Dickins <hughd@google.com>,
Jerome Glisse <jglisse@redhat.com>, Joe Perches <joe@perches.com>,
Lokesh Gidra <lokeshgidra@google.com>,
Mike Kravetz <mike.kravetz@oracle.com>,
Mike Rapoport <rppt@linux.vnet.ibm.com>, Shaohua Li <shli@fb.com>,
Shuah Khan <shuah@kernel.org>,
Stephen Rothwell <sfr@canb.auug.org.au>,
Wang Qing <wangqing@vivo.com>,
linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
linux-mm@kvack.org, Brian Geffon <bgeffon@google.com>,
"Dr . David Alan Gilbert" <dgilbert@redhat.com>,
Mina Almasry <almasrymina@google.com>,
Oliver Upton <oupton@google.com>
Subject: Re: [PATCH 2/9] userfaultfd/shmem: combine shmem_{mcopy_atomic,mfill_zeropage}_pte
Date: Mon, 12 Apr 2021 19:57:52 -0400 [thread overview]
Message-ID: <20210412235752.GC1002612@xz-x1> (raw)
In-Reply-To: <20210408234327.624367-3-axelrasmussen@google.com>
On Thu, Apr 08, 2021 at 04:43:20PM -0700, Axel Rasmussen wrote:
> Previously, we did a dance where we had one calling path in
> userfaultfd.c (mfill_atomic_pte), but then we split it into two in
> shmem_fs.h (shmem_{mcopy_atomic,mfill_zeropage}_pte), and then rejoined
> into a single shared function in shmem.c (shmem_mfill_atomic_pte).
>
> This is all a bit overly complex. Just call the single combined shmem
> function directly, allowing us to clean up various branches,
> boilerplate, etc.
>
> While we're touching this function, two other small cleanup changes:
> - offset is equivalent to pgoff, so we can get rid of offset entirely.
> - Split two VM_BUG_ON cases into two statements. This means the line
> number reported when the BUG is hit specifies exactly which condition
> was true.
(For my own preference, I'll avoid touching the latter one)
>
> Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>
> ---
> include/linux/shmem_fs.h | 15 +++++-------
> mm/shmem.c | 52 +++++++++++++---------------------------
> mm/userfaultfd.c | 10 +++-----
> 3 files changed, 25 insertions(+), 52 deletions(-)
>
> diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h
> index d82b6f396588..919e36671fe6 100644
> --- a/include/linux/shmem_fs.h
> +++ b/include/linux/shmem_fs.h
> @@ -122,21 +122,18 @@ static inline bool shmem_file(struct file *file)
> extern bool shmem_charge(struct inode *inode, long pages);
> extern void shmem_uncharge(struct inode *inode, long pages);
>
> +#ifdef CONFIG_USERFAULTFD
> #ifdef CONFIG_SHMEM
> extern int shmem_mcopy_atomic_pte(struct mm_struct *dst_mm, pmd_t *dst_pmd,
> struct vm_area_struct *dst_vma,
> unsigned long dst_addr,
> unsigned long src_addr,
Not a problem of your patch, but it's just that we passed in odd src_addr
values into mfill_atomic_pte() for zeropage case because we loop on src_addr in
__mcopy_atomic()... Then it'll further passed into shmem_mcopy_atomic_pte()
now after this patch (as shmem_mfill_zeropage_pte() probably only did one thing
good which is to clear src_addr). Not a big deal, though.
All the rest looks sane to me.
Reviewed-by: Peter Xu <peterx@redhat.com>
I'll wait to look at the selftests since in all cases they should be prone to
rebase (either based on the v2 cleanup I posted, or you'd need to post without
err() - then I can rebase again), so I figured maybe I just read the new
version.
Thanks,
--
Peter Xu
next prev parent reply other threads:[~2021-04-12 23:57 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-08 23:43 [PATCH 0/9] userfaultfd: add minor fault handling for shmem Axel Rasmussen
2021-04-08 23:43 ` [PATCH 1/9] userfaultfd/hugetlbfs: avoid including userfaultfd_k.h in hugetlb.h Axel Rasmussen
2021-04-12 23:47 ` Peter Xu
2021-04-08 23:43 ` [PATCH 2/9] userfaultfd/shmem: combine shmem_{mcopy_atomic,mfill_zeropage}_pte Axel Rasmussen
2021-04-12 23:57 ` Peter Xu [this message]
2021-04-08 23:43 ` [PATCH 3/9] userfaultfd/shmem: support minor fault registration for shmem Axel Rasmussen
2021-04-09 16:50 ` Peter Xu
2021-04-08 23:43 ` [PATCH 4/9] userfaultfd/shmem: support UFFDIO_CONTINUE " Axel Rasmussen
2021-04-12 23:17 ` Peter Xu
2021-04-13 4:40 ` Axel Rasmussen
2021-04-13 18:12 ` Peter Xu
2021-04-15 18:18 ` Axel Rasmussen
2021-04-08 23:43 ` [PATCH 5/9] userfaultfd/selftests: use memfd_create for shmem test type Axel Rasmussen
2021-04-08 23:43 ` [PATCH 6/9] userfaultfd/selftests: create alias mappings in the shmem test Axel Rasmussen
2021-04-08 23:43 ` [PATCH 7/9] userfaultfd/selftests: reinitialize test context in each test Axel Rasmussen
2021-04-08 23:43 ` [PATCH 8/9] userfaultfd/selftests: exercise minor fault handling shmem support Axel Rasmussen
2021-04-08 23:43 ` [PATCH 9/9] userfaultfd/shmem: modify shmem_mcopy_atomic_pte to use install_ptes Axel Rasmussen
2021-04-09 5:04 ` [PATCH 0/9] userfaultfd: add minor fault handling for shmem Andrew Morton
2021-04-09 17:03 ` Axel Rasmussen
2021-04-09 21:18 ` Peter Xu
2021-04-09 22:16 ` Mike Kravetz
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