From: SeongJae Park <sj@kernel.org>
To: Ryan Roberts <ryan.roberts@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
SeongJae Park <sj@kernel.org>,
Christoph Hellwig <hch@infradead.org>,
"Matthew Wilcox (Oracle)" <willy@infradead.org>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Lorenzo Stoakes <lstoakes@gmail.com>,
Uladzislau Rezki <urezki@gmail.com>, Zi Yan <ziy@nvidia.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
damon@lists.linux.dev, kernel test robot <lkp@intel.com>
Subject: Re: [PATCH v2 5/5] mm: ptep_deref() conversion
Date: Thu, 18 May 2023 17:22:11 +0000 [thread overview]
Message-ID: <20230518172211.84101-1-sj@kernel.org> (raw)
In-Reply-To: <20230518110727.2106156-6-ryan.roberts@arm.com>
On Thu, 18 May 2023 12:07:27 +0100 Ryan Roberts <ryan.roberts@arm.com> wrote:
> Convert all instances of direct pte_t* dereferencing to instead use
> ptep_deref() helper. By default, the helper does a direct dereference as
> before, but it can (and will) be overridden by the architecture to fully
> encapsulate the contents of the pte. Arch code is deliberately not
> converted, as the arch code knows best.
>
> Conversion was done using Coccinelle:
>
> ----
>
> // $ make coccicheck \
> // COCCI=ptepderef.cocci \
> // SPFLAGS="--include-headers" \
> // MODE=patch
>
> virtual patch
>
> @ depends on patch @
> pte_t *v;
> @@
>
> - *v
> + ptep_deref(v)
>
> ----
>
> Then reviewed and hand-edited to avoid multiple unnecessary calls to
> ptep_deref(), instead opting to store the result of a single in a
> variable, where it is correct to do so. This will benefit arch-overrides
> that may be more complex than a simple (optimizable) pointer
> dereference.
>
> Included is a fix for an issue in an earlier version of this patch that
> was pointed out by kernel test robot. The issue arose because config
> MMU=n elides definition of the ptep helper functions, including
> ptep_deref(). HUGETLB_PAGE=n configs still define a simple
> huge_ptep_clear_flush() for linking purposes, which dereferences the
> ptep. So when both configs are disabled, this caused a build error
> because ptep_deref() is not defined. Fix by continuing to do a direct
> dereference when MMU=n. This is safe because for this config the arch
> code cannot be trying to virtualize the ptes because none of the ptep
> helpers are defined.
>
> Reported-by: kernel test robot <lkp@intel.com>
> Link: https://lore.kernel.org/oe-kbuild-all/202305120142.yXsNEo6H-lkp@intel.com/
> Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
[...]
> mm/damon/ops-common.c | 2 +-
> mm/damon/paddr.c | 2 +-
> mm/damon/vaddr.c | 10 +-
For above mm/damon/ part,
Reviewed-by: SeongJae Park <sj@kernel.org>
Thanks,
SJ
prev parent reply other threads:[~2023-05-18 17:22 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-18 11:07 [PATCH v2 0/5] Encapsulate PTE contents from non-arch code Ryan Roberts
2023-05-18 11:07 ` [PATCH v2 1/5] mm: vmalloc must set pte via arch code Ryan Roberts
2023-05-19 12:09 ` Uladzislau Rezki
2023-05-24 18:47 ` Mike Rapoport
2023-05-18 11:07 ` [PATCH v2 2/5] mm: damon must atomically clear young on ptes and pmds Ryan Roberts
2023-05-18 17:13 ` SeongJae Park
2023-05-19 8:53 ` Ryan Roberts
2023-05-18 23:19 ` Yu Zhao
2023-05-19 9:02 ` Ryan Roberts
2023-05-19 19:54 ` SeongJae Park
2023-05-22 8:53 ` Ryan Roberts
2023-05-24 18:49 ` Mike Rapoport
2023-05-18 11:07 ` [PATCH v2 3/5] mm: Fix failure to unmap pte on highmem systems Ryan Roberts
2023-05-24 18:59 ` Mike Rapoport
2023-05-18 11:07 ` [PATCH v2 4/5] mm: Add new ptep_deref() helper to fully encapsulate pte_t Ryan Roberts
2023-05-18 19:28 ` Yu Zhao
2023-05-19 9:12 ` Ryan Roberts
2023-05-25 9:08 ` Ryan Roberts
2023-05-26 2:02 ` Yu Zhao
2023-05-24 19:06 ` Mike Rapoport
2023-05-24 19:11 ` Ryan Roberts
2023-05-18 11:07 ` [PATCH v2 5/5] mm: ptep_deref() conversion Ryan Roberts
2023-05-18 12:08 ` Jason Gunthorpe
2023-05-18 17:22 ` SeongJae Park [this message]
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