From: Chris Li <chrisl@kernel.org>
To: Barry Song <21cnbao@gmail.com>
Cc: akpm@linux-foundation.org, linux-mm@kvack.org,
baolin.wang@linux.alibaba.com, david@redhat.com,
hanchuanhua@oppo.com, hannes@cmpxchg.org, hughd@google.com,
kasong@tencent.com, linux-kernel@vger.kernel.org,
ryan.roberts@arm.com, surenb@google.com, v-songbaohua@oppo.com,
willy@infradead.org, xiang@kernel.org, ying.huang@intel.com,
yosryahmed@google.com, yuzhao@google.com, ziy@nvidia.com
Subject: Re: [PATCH v3 3/6] mm: introduce pte_move_swp_offset() helper which can move offset bidirectionally
Date: Fri, 3 May 2024 13:51:11 -0700 [thread overview]
Message-ID: <CANeU7Q=RFC7i6q=BjK3cXG+J0U2KeGMDuz0sV1K2sG2ifvpYcw@mail.gmail.com> (raw)
In-Reply-To: <20240503005023.174597-4-21cnbao@gmail.com>
On Thu, May 2, 2024 at 5:51 PM Barry Song <21cnbao@gmail.com> wrote:
>
> From: Barry Song <v-songbaohua@oppo.com>
>
> There could arise a necessity to obtain the first pte_t from a swap
> pte_t located in the middle. For instance, this may occur within the
> context of do_swap_page(), where a page fault can potentially occur in
> any PTE of a large folio. To address this, the following patch introduces
> pte_move_swp_offset(), a function capable of bidirectional movement by
> a specified delta argument. Consequently, pte_increment_swp_offset()
> will directly invoke it with delta = 1.
BTW, this patch has conflict with the latest mm-unstable. You might
need to refresh it.
I do not see the delta = -1 usage case here. Maybe merge the patch
with the follow up patch that uses the delta = -1?
Does delta only make sense as 1 and -1?
This patch doesn't seem straightly necessary to me.
Chris
Chris
>
> Suggested-by: "Huang, Ying" <ying.huang@intel.com>
> Signed-off-by: Barry Song <v-songbaohua@oppo.com>
> ---
> mm/internal.h | 25 +++++++++++++++++++++----
> 1 file changed, 21 insertions(+), 4 deletions(-)
>
> diff --git a/mm/internal.h b/mm/internal.h
> index c5552d35d995..cfe4aed66a5c 100644
> --- a/mm/internal.h
> +++ b/mm/internal.h
> @@ -211,18 +211,21 @@ static inline int folio_pte_batch(struct folio *folio, unsigned long addr,
> }
>
> /**
> - * pte_next_swp_offset - Increment the swap entry offset field of a swap pte.
> + * pte_move_swp_offset - Move the swap entry offset field of a swap pte
> + * forward or backward by delta
> * @pte: The initial pte state; is_swap_pte(pte) must be true and
> * non_swap_entry() must be false.
> + * @delta: The direction and the offset we are moving; forward if delta
> + * is positive; backward if delta is negative
> *
> - * Increments the swap offset, while maintaining all other fields, including
> + * Moves the swap offset, while maintaining all other fields, including
> * swap type, and any swp pte bits. The resulting pte is returned.
> */
> -static inline pte_t pte_next_swp_offset(pte_t pte)
> +static inline pte_t pte_move_swp_offset(pte_t pte, long delta)
> {
> swp_entry_t entry = pte_to_swp_entry(pte);
> pte_t new = __swp_entry_to_pte(__swp_entry(swp_type(entry),
> - (swp_offset(entry) + 1)));
> + (swp_offset(entry) + delta)));
>
> if (pte_swp_soft_dirty(pte))
> new = pte_swp_mksoft_dirty(new);
> @@ -234,6 +237,20 @@ static inline pte_t pte_next_swp_offset(pte_t pte)
> return new;
> }
>
> +
> +/**
> + * pte_next_swp_offset - Increment the swap entry offset field of a swap pte.
> + * @pte: The initial pte state; is_swap_pte(pte) must be true and
> + * non_swap_entry() must be false.
> + *
> + * Increments the swap offset, while maintaining all other fields, including
> + * swap type, and any swp pte bits. The resulting pte is returned.
> + */
> +static inline pte_t pte_next_swp_offset(pte_t pte)
> +{
> + return pte_move_swp_offset(pte, 1);
> +}
> +
> /**
> * swap_pte_batch - detect a PTE batch for a set of contiguous swap entries
> * @start_ptep: Page table pointer for the first entry.
> --
> 2.34.1
>
>
next prev parent reply other threads:[~2024-05-03 20:51 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-03 0:50 [PATCH v3 0/6] large folios swap-in: handle refault cases first Barry Song
2024-05-03 0:50 ` [PATCH v3 1/6] mm: swap: introduce swap_free_nr() for batched swap_free() Barry Song
2024-05-03 9:26 ` Ryan Roberts
2024-05-03 20:25 ` Chris Li
2024-05-08 7:35 ` Huang, Ying
2024-05-03 0:50 ` [PATCH v3 2/6] mm: remove swap_free() and always use swap_free_nr() Barry Song
2024-05-03 9:31 ` Ryan Roberts
2024-05-03 20:37 ` Chris Li
2024-05-04 4:03 ` Christoph Hellwig
2024-05-04 4:27 ` Barry Song
2024-05-04 4:28 ` Christoph Hellwig
2024-05-04 4:47 ` Barry Song
2024-05-08 7:56 ` Huang, Ying
2024-05-08 8:30 ` Barry Song
2024-05-08 9:10 ` Ryan Roberts
2024-05-03 0:50 ` [PATCH v3 3/6] mm: introduce pte_move_swp_offset() helper which can move offset bidirectionally Barry Song
2024-05-03 9:41 ` Ryan Roberts
2024-05-03 23:40 ` Barry Song
2024-05-06 8:06 ` David Hildenbrand
2024-05-06 8:20 ` Barry Song
2024-05-06 8:31 ` David Hildenbrand
2024-05-07 8:14 ` Ryan Roberts
2024-05-07 8:24 ` Barry Song
2024-05-07 9:39 ` Ryan Roberts
2024-05-03 20:51 ` Chris Li [this message]
2024-05-03 23:07 ` Barry Song
2024-05-08 8:08 ` Huang, Ying
2024-05-03 0:50 ` [PATCH v3 4/6] mm: introduce arch_do_swap_page_nr() which allows restore metadata for nr pages Barry Song
2024-05-03 10:02 ` Ryan Roberts
2024-05-06 16:51 ` Khalid Aziz
2024-05-03 0:50 ` [PATCH v3 5/6] mm: swap: make should_try_to_free_swap() support large-folio Barry Song
2024-05-03 0:50 ` [PATCH v3 6/6] mm: swap: entirely map large folios found in swapcache Barry Song
2024-05-03 10:50 ` Ryan Roberts
2024-05-03 23:23 ` Barry Song
2024-05-06 12:07 ` David Hildenbrand
2024-05-06 12:38 ` Barry Song
2024-05-06 12:58 ` Barry Song
2024-05-06 13:16 ` David Hildenbrand
2024-05-06 22:58 ` Barry Song
2024-05-07 8:24 ` David Hildenbrand
2024-05-07 8:43 ` Barry Song
2024-05-07 8:59 ` David Hildenbrand
2024-05-07 9:24 ` Barry Song
2024-05-07 10:39 ` David Hildenbrand
2024-05-07 10:48 ` Barry Song
2024-05-07 8:17 ` Ryan Roberts
2024-05-06 12:05 ` David Hildenbrand
2024-05-06 12:27 ` Barry Song
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