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X-CSE-ConnectionGUID: MQNBTv/rTNej3svV4K0qDg== X-CSE-MsgGUID: x8PmSMDiRf2m0dw8n5Ol1Q== X-IronPort-AV: E=McAfee;i="6600,9927,11066"; a="10845300" X-IronPort-AV: E=Sophos;i="6.08,144,1712646000"; d="scan'208";a="10845300" Received: from orviesa008.jf.intel.com ([10.64.159.148]) by fmvoesa112.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 May 2024 01:10:56 -0700 X-CSE-ConnectionGUID: kAvrKWCvRniONnhB8OO5sg== X-CSE-MsgGUID: CRmLOhA8ROSKgO52UJ0qTQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.08,144,1712646000"; d="scan'208";a="29384745" Received: from unknown (HELO yhuang6-desk2.ccr.corp.intel.com) ([10.238.208.55]) by orviesa008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 May 2024 01:10:51 -0700 From: "Huang, Ying" To: Barry Song <21cnbao@gmail.com> Cc: akpm@linux-foundation.org, linux-mm@kvack.org, baolin.wang@linux.alibaba.com, chrisl@kernel.org, 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, 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 In-Reply-To: <20240503005023.174597-4-21cnbao@gmail.com> (Barry Song's message of "Fri, 3 May 2024 12:50:20 +1200") References: <20240503005023.174597-1-21cnbao@gmail.com> <20240503005023.174597-4-21cnbao@gmail.com> Date: Wed, 08 May 2024 16:08:59 +0800 Message-ID: <87ttj8iv38.fsf@yhuang6-desk2.ccr.corp.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii X-Rspam-User: X-Stat-Signature: wnd3kppi5g93z41z9n8keeky4neu8sd4 X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 8C93580014 X-HE-Tag: 1715155857-451922 X-HE-Meta: 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 9155lekV UjKyelWmQrlb2I89q5IltxKUILjX/UM0qZLd60ZTh9PZOWPQMXkVe6z4iTO/TW9+jiSmwWfajYbzzK/K2tP4JZ3wJ1X3UJQNtKoWyo++ryvr7WoQ93SPMPRlt3pU19Y5ce18cS+Mu3m0I2n+1HOhgkEMNzyleQ+SSsLv7dtP20avd0TmDgGRD0yOGR8gXB4JpUEGU8g0DjH21v1Ts88wKkDL4LZdXd0ASAashfoQF7IbDAmjdbjGA4cFM44SaHKfa3Zy3dItlVnpjYu8Mp6C6gU79K2LUEYlTxlMXkn4R819x1dZpnENxfKtpWHjc/6KruvleSpgQJ9V457k= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Barry Song <21cnbao@gmail.com> writes: > From: Barry Song > > 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. > > Suggested-by: "Huang, Ying" > Signed-off-by: Barry Song LGTM, Thanks! Feel free to add Reviewed-by: "Huang, Ying" in the future version. > --- > 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. -- Best Regards, Huang, Ying