From nobody Sat Oct 11 00:25:21 2025 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.223.130]) (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 7110E24DCE2 for ; Thu, 12 Jun 2025 13:47:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=195.135.223.130 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749736059; cv=none; b=Uz43E6xCYZw0w2Z67rvehBVcZzW5QrcsWkOoOHR73Zgq2NnQUhEQYQl9oIIlPD7uMZSnuT8CUch19m/ZIdNzf0pTVXJs2SXV5dZzywjFsZtSrtIfN2dXBITzTa8OqlisFr8GmeTJTHWVjsKgD9ghTNBau6gZo/b09xLztVeanrI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749736059; c=relaxed/simple; bh=Dx4F4kRLv6WKbLr8ZOEav4L6SeKUI6GtppIcl6bTmWI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=IQiDLdQo9NsnJO/16uqH3PIoGtBboRJnjZD/ev2GkObOWKd/jM334DfVa5OPKljIFzvpykd8r7N6XZn4UQ5d+BaAgnJEl7egPVwhli9HFqN0Yuk20Sg0wovdhErR6WxpLfHUXRm9nUH8xaLNb7qWE/qZx8OnJ4OiU4Gs6M3AO9s= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=suse.de; spf=pass smtp.mailfrom=suse.de; dkim=pass (1024-bit key) header.d=suse.de header.i=@suse.de header.b=NDU1ewJH; dkim=permerror (0-bit key) header.d=suse.de header.i=@suse.de header.b=Ldl6zGXA; dkim=pass (1024-bit key) header.d=suse.de header.i=@suse.de header.b=NDU1ewJH; dkim=permerror (0-bit key) header.d=suse.de header.i=@suse.de header.b=Ldl6zGXA; arc=none smtp.client-ip=195.135.223.130 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=suse.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=suse.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=suse.de header.i=@suse.de header.b="NDU1ewJH"; dkim=permerror (0-bit key) header.d=suse.de header.i=@suse.de header.b="Ldl6zGXA"; dkim=pass (1024-bit key) header.d=suse.de header.i=@suse.de header.b="NDU1ewJH"; dkim=permerror (0-bit key) header.d=suse.de header.i=@suse.de header.b="Ldl6zGXA" Received: from imap1.dmz-prg2.suse.org (imap1.dmz-prg2.suse.org [IPv6:2a07:de40:b281:104:10:150:64:97]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 0418321986; Thu, 12 Jun 2025 13:47:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1749736039; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=N8oNzaGUW5qLujz6KN4jF5cE4+hRczq1P7iZs6uKvYo=; b=NDU1ewJHuBxYRllt+TaN9nMUngGutNhrt90DaRyImP86NuxFgs9h1gouiXhfE4kzn6SV4x EzF/7BPM4VP6Z0Uwsnti6mCZwHxMmCMaDHmSYlTmvUfnUuO5Q3W0ve0vtzRqV9RK8Dy66X ZdXJDUkmCv67B5qQsQYNXEHlzOHgWkA= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1749736039; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=N8oNzaGUW5qLujz6KN4jF5cE4+hRczq1P7iZs6uKvYo=; b=Ldl6zGXAuCxWWfrJeMN/RWS+oyQKET0q4r8Fmi32QBKRYrPJ0VqDbRg4NcFFAa5aLQQIMx WGPnyaHqB+A91+CA== Authentication-Results: smtp-out1.suse.de; dkim=pass header.d=suse.de header.s=susede2_rsa header.b=NDU1ewJH; dkim=pass header.d=suse.de header.s=susede2_ed25519 header.b=Ldl6zGXA DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1749736039; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=N8oNzaGUW5qLujz6KN4jF5cE4+hRczq1P7iZs6uKvYo=; b=NDU1ewJHuBxYRllt+TaN9nMUngGutNhrt90DaRyImP86NuxFgs9h1gouiXhfE4kzn6SV4x EzF/7BPM4VP6Z0Uwsnti6mCZwHxMmCMaDHmSYlTmvUfnUuO5Q3W0ve0vtzRqV9RK8Dy66X ZdXJDUkmCv67B5qQsQYNXEHlzOHgWkA= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1749736039; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=N8oNzaGUW5qLujz6KN4jF5cE4+hRczq1P7iZs6uKvYo=; b=Ldl6zGXAuCxWWfrJeMN/RWS+oyQKET0q4r8Fmi32QBKRYrPJ0VqDbRg4NcFFAa5aLQQIMx WGPnyaHqB+A91+CA== Received: from imap1.dmz-prg2.suse.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by imap1.dmz-prg2.suse.org (Postfix) with ESMTPS id 7B66D132D8; Thu, 12 Jun 2025 13:47:18 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id GACBG2baSmhJEAAAD6G6ig (envelope-from ); Thu, 12 Jun 2025 13:47:18 +0000 From: Oscar Salvador To: Andrew Morton Cc: David Hildenbrand , Muchun Song , James Houghton , Peter Xu , Gavin Guo , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Oscar Salvador Subject: [PATCH 4/5] mm,hugetlb: Drop obsolete comment about non-present pte and second faults Date: Thu, 12 Jun 2025 15:47:00 +0200 Message-ID: <20250612134701.377855-5-osalvador@suse.de> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250612134701.377855-1-osalvador@suse.de> References: <20250612134701.377855-1-osalvador@suse.de> 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 X-Spamd-Result: default: False [-3.01 / 50.00]; BAYES_HAM(-3.00)[100.00%]; MID_CONTAINS_FROM(1.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; R_MISSING_CHARSET(0.50)[]; NEURAL_HAM_SHORT(-0.20)[-1.000]; R_DKIM_ALLOW(-0.20)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; MIME_TRACE(0.00)[0:+]; ARC_NA(0.00)[]; TO_DN_SOME(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; RBL_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:104:10:150:64:97:from]; FUZZY_BLOCKED(0.00)[rspamd.com]; RCVD_TLS_ALL(0.00)[]; DKIM_TRACE(0.00)[suse.de:+]; RCVD_COUNT_TWO(0.00)[2]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; SPAMHAUS_XBL(0.00)[2a07:de40:b281:104:10:150:64:97:from]; RCPT_COUNT_SEVEN(0.00)[9]; RCVD_VIA_SMTP_AUTH(0.00)[]; RECEIVED_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:106:10:150:64:167:received]; R_RATELIMIT(0.00)[to_ip_from(RL9xiirkf5437rzygec8i7198k)]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:dkim,suse.de:mid,suse.de:email,imap1.dmz-prg2.suse.org:helo,imap1.dmz-prg2.suse.org:rdns] X-Spam-Level: X-Spam-Flag: NO X-Rspamd-Queue-Id: 0418321986 X-Rspamd-Action: no action X-Rspamd-Server: rspamd1.dmz-prg2.suse.org X-Spam-Score: -3.01 Content-Type: text/plain; charset="utf-8" There is a comment in hugetlb_fault() that does not hold anymore. This one: /* * vmf.orig_pte could be a migration/hwpoison vmf.orig_pte at this * point, so this check prevents the kernel from going below assuming * that we have an active hugepage in pagecache. This goto expects * the 2nd page fault, and is_hugetlb_entry_(migration|hwpoisoned) * check will properly handle it. */ This was written because back in the day we used to do: hugetlb_fault () { ptep =3D huge_pte_offset(...) if (ptep) { entry =3D huge_ptep_get(ptep) if (unlikely(is_hugetlb_entry_migration(entry)) ... else if (unlikely(is_hugetlb_entry_hwpoisoned(entry))) ... } ... ... /* * entry could be a migration/hwpoison entry at this point, so this * check prevents the kernel from going below assuming that we have * a active hugepage in pagecache. This goto expects the 2nd page fault, * and is_hugetlb_entry_(migration|hwpoisoned) check will properly * handle it. */ if (!pte_present(entry)) goto out_mutex; ... } The code was designed to check for hwpoisoned/migration entries upfront, and then bail out if further down the pte was not present anymore, relying on the second fault to properly handle migration/hwpoison entries t= hat time around. The way we handle this is different nowadays, so drop the misleading commen= t. Signed-off-by: Oscar Salvador --- mm/hugetlb.c | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 62bc3808f99e..ad377e24b7d0 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -6742,13 +6742,7 @@ vm_fault_t hugetlb_fault(struct mm_struct *mm, struc= t vm_area_struct *vma, =20 ret =3D 0; =20 - /* - * vmf.orig_pte could be a migration/hwpoison vmf.orig_pte at this - * point, so this check prevents the kernel from going below assuming - * that we have an active hugepage in pagecache. This goto expects - * the 2nd page fault, and is_hugetlb_entry_(migration|hwpoisoned) - * check will properly handle it. - */ + /* Not present, either a migration or a hwpoisoned entry */ if (!pte_present(vmf.orig_pte)) { if (unlikely(is_hugetlb_entry_migration(vmf.orig_pte))) { /* --=20 2.49.0