From nobody Thu Oct 9 06:51:15 2025 Received: from mail-pl1-f169.google.com (mail-pl1-f169.google.com [209.85.214.169]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 47BFB28DF1D for ; Thu, 19 Jun 2025 17:55:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.169 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750355755; cv=none; b=CUej1wlcyPf6UV0j+VLqMZ0uJA86du8BtTFd1Q1U08olocDMZ8BUhjso46q5XISitCqDkb7q1jdYRpEUHNijGDhWl0Q7+MsbOwhcb9Ny/hCQHihAcIkwb8aR82iukPzshwEutw5wLVtNDUKy06eP2Slz11j5olrGbmFiA7tWnCc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750355755; c=relaxed/simple; bh=JzMTjZB49BCjwvIcUPEM+HFWvW8HtJQKVeXy4jJnSio=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=rHHM8njO8MxIRFIeBXWd3Iu1ITQUVr311bZzIh7LG+LVS4nUQOJgYf85xge0FodCMX9wtK/8Fj9tQe6onHMDIB9d+nxLdZ4bXi3PnSo5uisikGrXbJkWSo5Q0QDFR2Ryf4V+eaKmJlAaUkCBhJ3IRDz9VQKn19p/PTWXSugzhy4= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=RLZBQ8Jd; arc=none smtp.client-ip=209.85.214.169 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="RLZBQ8Jd" Received: by mail-pl1-f169.google.com with SMTP id d9443c01a7336-22c33677183so9255845ad.2 for ; Thu, 19 Jun 2025 10:55:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1750355753; x=1750960553; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:reply-to:references :in-reply-to:message-id:date:subject:cc:to:from:from:to:cc:subject :date:message-id:reply-to; bh=qhxEiBYif/YKCDyTxEvEnwXoCgIUrrgaAQ2W3uziJ+o=; b=RLZBQ8JdnxFU1+RdyTpkk3UHGvjkojg7YhbwbkJ/xvkhKXma1s/CEgMylNNq5fhQ6d 0yFjnXKEq+Q6EsppRNHD9MIw1d6Z31CUURvQfrN5+zh0aRgUiyoV7vJLkGwNKSopOJed oSLvWD+T7pgH59qRxovZmY9mjtJLwBWz0fDc/4Ly6B/LCJTlqb37mILW1gYCeoUB0TIW VQprnKsF7gQYAdhv2KCks41VH73IljMIQAfWDGWVDrrMWnG5rvDXZFekZ1tZsDFRvDB0 R+4aNymTKQYK2TqxmDLGQt0/bK5A+qDeAO4Cy6fG+kUO53I2F+l7MSokVmFbbOMcjRUG 8+gw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1750355753; x=1750960553; h=content-transfer-encoding:mime-version:reply-to:references :in-reply-to:message-id:date:subject:cc:to:from:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=qhxEiBYif/YKCDyTxEvEnwXoCgIUrrgaAQ2W3uziJ+o=; b=ZBfaY478eJVrm1nfZPydZhrb2OOP0Nf6b0j+qhghsCgf6142UkvvKxm5qkPi/trKnJ QVhgXfZ0P3rT4TN8OrJ90RdyETKV5ZjCdc/1scstXE8EgWHr+oW04o0XkEXS3uuV3rFJ ogwR9N5W/IRIkQVIdp9IHsuOEssK21Y9V988cAjFrHgj7h6gelLFRYwkhayL49alho60 Xf4wSbZ4gn5E1oTIPUpZL4G9JEaponoG+g8Xq8a2+jZuBu2A6UYJjZ9NuJ+BJY5gxMIM G18tb2CcK9N2bUSRh4keGqAqAYrLzDYZ3H+QXbgkp8pXnwLln4JSMxRAWJSyFpAFXYdr bWkw== X-Forwarded-Encrypted: i=1; AJvYcCW0OjjOz9rMuCdSTR5n0uL06KkXwe86Yqp+0k6zY6ZkBR0BDMIZaw2XnSZwrbcFrHTPZMsPHKEKhqFQk3c=@vger.kernel.org X-Gm-Message-State: AOJu0YzRPPrc6kdYMY57XyWDK7W0TP+zlCjlcFcPZR9j3hbr9jgjYO+Y p9qaivzapo1dDNea8kyH1kDH2nFeRj6yhzVCoLaSuKJeWscwMtwplNoq X-Gm-Gg: ASbGnctwMisVy/LFHh3EtdsymLrVXL3vc0CA3LaBFHnRUedPsKkeYgeB/Yalnz4kXgj P1hYa99YK3aevTB6xan9GHCjYsY2VW0OHumltwvabYZLqy9hyIBlLY4wGOcmPNvVum49RZHeiRC rD3GcVlBPeyNVODqf/1miXjoO5yK0d4X4Nl+ePFULwDt1c2SmgqHT21PQ8Kgt1EP5r1w8JDsacX y1tMT+AY8OHgxqw9jUEvF9AoWxK5Xe04jSN7RNXafLrX9t1IHlKjvP3puS09hMS5GxzY1DBaOd9 Lwm8Fu57N4ZxtlXtcYLsMOurnH4tYQBshMsOYHsLaziL6uFeLXbkJbiPA84nY2NXYgBCzA/W7KZ cdS1bWAKq1Hsrq2oFkw== X-Google-Smtp-Source: AGHT+IEJFgdALACITfgwxqQ56cWatjSGdDaAunvgPQAqa+5FC5hRIuAlEC9S5QqI+0+fDBmHXigCPQ== X-Received: by 2002:a17:903:22c8:b0:234:8a4a:adad with SMTP id d9443c01a7336-2366b14d484mr326770805ad.26.1750355753431; Thu, 19 Jun 2025 10:55:53 -0700 (PDT) Received: from KASONG-MC4.tencent.com ([101.32.222.185]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-237d83efa44sm255215ad.77.2025.06.19.10.55.50 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Thu, 19 Jun 2025 10:55:52 -0700 (PDT) From: Kairui Song To: linux-mm@kvack.org Cc: Andrew Morton , Hugh Dickins , Baolin Wang , Matthew Wilcox , Kemeng Shi , Chris Li , Nhat Pham , Baoquan He , Barry Song , linux-kernel@vger.kernel.org, Kairui Song Subject: [PATCH v2 2/4] mm/shmem, swap: avoid redundant Xarray lookup during swapin Date: Fri, 20 Jun 2025 01:55:36 +0800 Message-ID: <20250619175538.15799-3-ryncsn@gmail.com> X-Mailer: git-send-email 2.50.0 In-Reply-To: <20250619175538.15799-1-ryncsn@gmail.com> References: <20250619175538.15799-1-ryncsn@gmail.com> Reply-To: Kairui Song Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Kairui Song Currently shmem calls xa_get_order to get the swap radix entry order, requiring a full tree walk. This can be easily combined with the swap entry value checking (shmem_confirm_swap) to avoid the duplicated lookup, which should improve the performance. Signed-off-by: Kairui Song Reviewed-by: Kemeng Shi Reviewed-by: Baolin Wang Reviewed-by: Dev Jain --- mm/shmem.c | 33 ++++++++++++++++++++++++--------- 1 file changed, 24 insertions(+), 9 deletions(-) diff --git a/mm/shmem.c b/mm/shmem.c index 4e7ef343a29b..ce44d1da08cd 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -505,15 +505,27 @@ static int shmem_replace_entry(struct address_space *= mapping, =20 /* * Sometimes, before we decide whether to proceed or to fail, we must check - * that an entry was not already brought back from swap by a racing thread. + * that an entry was not already brought back or split by a racing thread. * * Checking folio is not enough: by the time a swapcache folio is locked, = it * might be reused, and again be swapcache, using the same swap as before. + * Returns the swap entry's order if it still presents, else returns -1. */ -static bool shmem_confirm_swap(struct address_space *mapping, - pgoff_t index, swp_entry_t swap) +static int shmem_confirm_swap(struct address_space *mapping, pgoff_t index, + swp_entry_t swap) { - return xa_load(&mapping->i_pages, index) =3D=3D swp_to_radix_entry(swap); + XA_STATE(xas, &mapping->i_pages, index); + int ret =3D -1; + void *entry; + + rcu_read_lock(); + do { + entry =3D xas_load(&xas); + if (entry =3D=3D swp_to_radix_entry(swap)) + ret =3D xas_get_order(&xas); + } while (xas_retry(&xas, entry)); + rcu_read_unlock(); + return ret; } =20 /* @@ -2256,16 +2268,20 @@ static int shmem_swapin_folio(struct inode *inode, = pgoff_t index, return -EIO; =20 si =3D get_swap_device(swap); - if (!si) { - if (!shmem_confirm_swap(mapping, index, swap)) + order =3D shmem_confirm_swap(mapping, index, swap); + if (unlikely(!si)) { + if (order < 0) return -EEXIST; else return -EINVAL; } + if (unlikely(order < 0)) { + put_swap_device(si); + return -EEXIST; + } =20 /* Look it up and read it in.. */ folio =3D swap_cache_get_folio(swap, NULL, 0); - order =3D xa_get_order(&mapping->i_pages, index); if (!folio) { int nr_pages =3D 1 << order; bool fallback_order0 =3D false; @@ -2415,7 +2431,7 @@ static int shmem_swapin_folio(struct inode *inode, pg= off_t index, *foliop =3D folio; return 0; failed: - if (!shmem_confirm_swap(mapping, index, swap)) + if (shmem_confirm_swap(mapping, index, swap) < 0) error =3D -EEXIST; if (error =3D=3D -EIO) shmem_set_folio_swapin_error(inode, index, folio, swap, @@ -2428,7 +2444,6 @@ static int shmem_swapin_folio(struct inode *inode, pg= off_t index, folio_put(folio); } put_swap_device(si); - return error; } =20 --=20 2.50.0