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X-IronPort-AV: E=McAfee;i="6600,9927,10942"; a="15800669" X-IronPort-AV: E=Sophos;i="6.04,330,1695711600"; d="scan'208";a="15800669" Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by orvoesa101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 04 Jan 2024 00:12:58 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10942"; a="783797439" X-IronPort-AV: E=Sophos;i="6.04,330,1695711600"; d="scan'208";a="783797439" Received: from yhuang6-desk2.sh.intel.com (HELO yhuang6-desk2.ccr.corp.intel.com) ([10.238.208.55]) by fmsmga007-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 04 Jan 2024 00:12:54 -0800 From: "Huang, Ying" To: Kairui Song Cc: linux-mm@kvack.org, Kairui Song , Andrew Morton , Chris Li , Hugh Dickins , Johannes Weiner , Matthew Wilcox , Michal Hocko , Yosry Ahmed , David Hildenbrand , linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 3/9] mm/swap: avoid doing extra unlock error checks for direct swapin In-Reply-To: <20240102175338.62012-4-ryncsn@gmail.com> (Kairui Song's message of "Wed, 3 Jan 2024 01:53:32 +0800") References: <20240102175338.62012-1-ryncsn@gmail.com> <20240102175338.62012-4-ryncsn@gmail.com> Date: Thu, 04 Jan 2024 16:10:56 +0800 Message-ID: <87le95bjsf.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-Rspamd-Queue-Id: 6E3C2A0017 X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: n7zmxgsa47ejm7s7br1q9mq6sufjigwj X-HE-Tag: 1704355979-97661 X-HE-Meta: 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 YzYzMeB/ yyLHFYe5H+K8uWASApbQT3LeOcHDDr7The5jsjJDmSXD7jI44XeS+hZG/b2PzNsOLkZ53guJGq69y1UXDikpmaptiPaald2WD9Dc1dxM7lGQMAy5Xe8NUch45JFNmsAugUUvpFOIjoZPQIsShja+q1kVM4fOxRUgZARZAK4G6nAX+jve7ZheOmxDVBjct/fHMSXlTvQaX51njD0MgMvbedp4NvcvYY73N273k3bDLlR9mGmFxT1xwYnNbWNPnXtvdWkuR 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: Kairui Song writes: > From: Kairui Song > > When swapping in a page, mem_cgroup_swapin_charge_folio is called for > new allocated folio, nothing else is referencing the folio so no need > to set the lock bit early. This avoided doing extra unlock checks > on the error path. > > Signed-off-by: Kairui Song > --- > mm/swap_state.c | 13 ++++++------- > 1 file changed, 6 insertions(+), 7 deletions(-) > > diff --git a/mm/swap_state.c b/mm/swap_state.c > index 24cb93ed5081..6130de8d5226 100644 > --- a/mm/swap_state.c > +++ b/mm/swap_state.c > @@ -881,16 +881,15 @@ struct folio *swapin_direct(swp_entry_t entry, gfp_t gfp_mask, > folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0, > vma, vmf->address, false); > if (folio) { > - __folio_set_locked(folio); > - __folio_set_swapbacked(folio); > - > - if (mem_cgroup_swapin_charge_folio(folio, > - vma->vm_mm, GFP_KERNEL, > - entry)) { > - folio_unlock(folio); > + if (mem_cgroup_swapin_charge_folio(folio, vma->vm_mm, > + GFP_KERNEL, entry)) { > folio_put(folio); > return NULL; > } > + > + __folio_set_locked(folio); > + __folio_set_swapbacked(folio); > + > mem_cgroup_swapin_uncharge_swap(entry); > > shadow = get_shadow_from_swap_cache(entry); I don't find any issue with the patch. But another caller of mem_cgroup_swapin_charge_folio() in __read_swap_cache_async() setups newly allocated folio in the same way before the change. Better to keep them same? Because the benefit of change is small too. -- Best Regards, Huang, Ying