From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.9]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 68DE9200BA for ; Thu, 4 Jan 2024 08:12:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="hWwQqYCj" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1704355979; x=1735891979; h=from:to:cc:subject:in-reply-to:references:date: message-id:mime-version; bh=w7QdWCpRC9c2jKavjd+5JRPpXv4v1PAmsnvPkAZilfc=; b=hWwQqYCjyZFvD5+esyOp3ytzDPalfJe9lP2BKDEbUQJY1P1XCEqDCRLD gkrzN451LSGMb9f2MQfH5bonabMYh9Dslvj1172gVaFpwv7xUG+fw2F9H QfeKiSydIHz6Ql2Tw2DM2tgqIIeSSxQiz6zvP0DPD/ewx6FhKNPSZUuPk 91acnHhp9cZRDyVGiNPY/UEIrhM6RmMZzThzIGiXsWbr3yAKgr1gYHbH5 q3V0QCFA0ruuPZ1iJUo20PgSV4sZyzZNUZZAp+jTR/WSZTvbkDaf5Roi4 /DqlVj7B9aQyPhajqEOfMKw9xT68e15Izo3ZjPMfidhG+LUWBCVjBiwN5 Q==; X-IronPort-AV: E=McAfee;i="6600,9927,10942"; a="15800670" X-IronPort-AV: E=Sophos;i="6.04,330,1695711600"; d="scan'208";a="15800670" 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) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ascii 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