From nobody Wed Feb 11 06:31:51 2026 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 334481FBEBF for ; Mon, 24 Feb 2025 21:59:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740434377; cv=none; b=YapS/yUzRfcUIY0sKz4Vy6NsgupC8xueVk6sTLXFAh0XzuTQRcZAmMN4uAK23VhGB70ELdLhPyNJud4mBeWgmJ0KVa3FMJdDfiMn03HWT0DO/xJxPCFxvNlHmnGBFwX3XlR3CnotVU7Rw4hNdlBzGn/j8nojaVqvjMjQM/PVPyU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1740434377; c=relaxed/simple; bh=tYAQ3aSW354yzsYqD4JxVDZTKN8sBGftkdhW2t84PpQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=tjSEihzjcZ+k8pg5TsrZZPc5ztrXjLvi7vwpou3jtxklb2tYsZ1F9FfPo5Zyop6iYceGLNMlAu9L52XQgnA2BqSpaiS3Ecu2gQU8+k5lVVqFXsI0lCcEdjQOg6MOJ+WM004ukUpWZAClpyvmnADZ8FELDRjLWiWKfmitGjD4iEg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=MlIThKYl; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="MlIThKYl" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1740434374; h=from:from:reply-to:subject:subject: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=6w7eedefm4DE2XJ3Yn/BDysgoHUEY0apu1z5eddMX8Y=; b=MlIThKYlqRQXAUODBzZWDgWm+tnsJ3U9iqxIgqpqaO3l0mEQ2/HoNy/uWv0r22bqK25FcS ilWQyLKSzCCI916rr0XeWM4iWsW+HfuayG//3i1pmO2yByc8ij2q6bYhTtLTm/p2uK8B2s 0S5SlvpIE0IAgiy2qNeqr4I5VZZT4o0= Received: from mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-350-JQXE_8nIOY-3y1mHgNHfUw-1; Mon, 24 Feb 2025 16:59:29 -0500 X-MC-Unique: JQXE_8nIOY-3y1mHgNHfUw-1 X-Mimecast-MFC-AGG-ID: JQXE_8nIOY-3y1mHgNHfUw_1740434368 Received: from mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.93]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id AC91419560B9; Mon, 24 Feb 2025 21:59:27 +0000 (UTC) Received: from fedora.redhat.com (unknown [10.22.65.50]) by mx-prod-int-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id C092D180035F; Mon, 24 Feb 2025 21:59:25 +0000 (UTC) From: Luiz Capitulino To: linux-kernel@vger.kernel.org, linux-mm@kvack.org, david@redhat.com, yuzhao@google.com, pasha.tatashin@soleen.com Cc: akpm@linux-foundation.org, hannes@cmpxchg.org, muchun.song@linux.dev, luizcap@redhat.com Subject: [PATCH v2 4/4] mm: page_owner: use new iteration API Date: Mon, 24 Feb 2025 16:59:08 -0500 Message-ID: In-Reply-To: References: 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-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 Content-Type: text/plain; charset="utf-8" The page_ext_next() function assumes that page extension objects for a page order allocation always reside in the same memory section, which may not be true and could lead to crashes. Use the new page_ext iteration API instead. Fixes: cf54f310d0d3 ("mm/hugetlb: use __GFP_COMP for gigantic folios") Signed-off-by: Luiz Capitulino --- mm/page_owner.c | 61 +++++++++++++++++++++++-------------------------- 1 file changed, 29 insertions(+), 32 deletions(-) diff --git a/mm/page_owner.c b/mm/page_owner.c index 2d6360eaccbb6..c9d2c688eb981 100644 --- a/mm/page_owner.c +++ b/mm/page_owner.c @@ -229,17 +229,19 @@ static void dec_stack_record_count(depot_stack_handle= _t handle, handle); } =20 -static inline void __update_page_owner_handle(struct page_ext *page_ext, +static inline void __update_page_owner_handle(struct page *page, depot_stack_handle_t handle, unsigned short order, gfp_t gfp_mask, short last_migrate_reason, u64 ts_nsec, pid_t pid, pid_t tgid, char *comm) { - int i; + struct page_ext_iter iter; + struct page_ext *page_ext; struct page_owner *page_owner; =20 - for (i =3D 0; i < (1 << order); i++) { + rcu_read_lock(); + for_each_page_ext(page, 1 << order, page_ext, iter) { page_owner =3D get_page_owner(page_ext); page_owner->handle =3D handle; page_owner->order =3D order; @@ -252,20 +254,22 @@ static inline void __update_page_owner_handle(struct = page_ext *page_ext, sizeof(page_owner->comm)); __set_bit(PAGE_EXT_OWNER, &page_ext->flags); __set_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags); - page_ext =3D page_ext_next(page_ext); } + rcu_read_unlock(); } =20 -static inline void __update_page_owner_free_handle(struct page_ext *page_e= xt, +static inline void __update_page_owner_free_handle(struct page *page, depot_stack_handle_t handle, unsigned short order, pid_t pid, pid_t tgid, u64 free_ts_nsec) { - int i; + struct page_ext_iter iter; + struct page_ext *page_ext; struct page_owner *page_owner; =20 - for (i =3D 0; i < (1 << order); i++) { + rcu_read_lock(); + for_each_page_ext(page, 1 << order, page_ext, iter) { page_owner =3D get_page_owner(page_ext); /* Only __reset_page_owner() wants to clear the bit */ if (handle) { @@ -275,8 +279,8 @@ static inline void __update_page_owner_free_handle(stru= ct page_ext *page_ext, page_owner->free_ts_nsec =3D free_ts_nsec; page_owner->free_pid =3D current->pid; page_owner->free_tgid =3D current->tgid; - page_ext =3D page_ext_next(page_ext); } + rcu_read_unlock(); } =20 void __reset_page_owner(struct page *page, unsigned short order) @@ -293,11 +297,11 @@ void __reset_page_owner(struct page *page, unsigned s= hort order) =20 page_owner =3D get_page_owner(page_ext); alloc_handle =3D page_owner->handle; + page_ext_put(page_ext); =20 handle =3D save_stack(GFP_NOWAIT | __GFP_NOWARN); - __update_page_owner_free_handle(page_ext, handle, order, current->pid, + __update_page_owner_free_handle(page, handle, order, current->pid, current->tgid, free_ts_nsec); - page_ext_put(page_ext); =20 if (alloc_handle !=3D early_handle) /* @@ -313,19 +317,13 @@ void __reset_page_owner(struct page *page, unsigned s= hort order) noinline void __set_page_owner(struct page *page, unsigned short order, gfp_t gfp_mask) { - struct page_ext *page_ext; u64 ts_nsec =3D local_clock(); depot_stack_handle_t handle; =20 handle =3D save_stack(gfp_mask); - - page_ext =3D page_ext_get(page); - if (unlikely(!page_ext)) - return; - __update_page_owner_handle(page_ext, handle, order, gfp_mask, -1, + __update_page_owner_handle(page, handle, order, gfp_mask, -1, ts_nsec, current->pid, current->tgid, current->comm); - page_ext_put(page_ext); inc_stack_record_count(handle, gfp_mask, 1 << order); } =20 @@ -344,26 +342,24 @@ void __set_page_owner_migrate_reason(struct page *pag= e, int reason) =20 void __split_page_owner(struct page *page, int old_order, int new_order) { - int i; - struct page_ext *page_ext =3D page_ext_get(page); + struct page_ext_iter iter; + struct page_ext *page_ext; struct page_owner *page_owner; =20 - if (unlikely(!page_ext)) - return; - - for (i =3D 0; i < (1 << old_order); i++) { + rcu_read_lock(); + for_each_page_ext(page, 1 << old_order, page_ext, iter) { page_owner =3D get_page_owner(page_ext); page_owner->order =3D new_order; - page_ext =3D page_ext_next(page_ext); } - page_ext_put(page_ext); + rcu_read_unlock(); } =20 void __folio_copy_owner(struct folio *newfolio, struct folio *old) { - int i; struct page_ext *old_ext; struct page_ext *new_ext; + struct page_ext *page_ext; + struct page_ext_iter iter; struct page_owner *old_page_owner; struct page_owner *new_page_owner; depot_stack_handle_t migrate_handle; @@ -381,7 +377,7 @@ void __folio_copy_owner(struct folio *newfolio, struct = folio *old) old_page_owner =3D get_page_owner(old_ext); new_page_owner =3D get_page_owner(new_ext); migrate_handle =3D new_page_owner->handle; - __update_page_owner_handle(new_ext, old_page_owner->handle, + __update_page_owner_handle(&newfolio->page, old_page_owner->handle, old_page_owner->order, old_page_owner->gfp_mask, old_page_owner->last_migrate_reason, old_page_owner->ts_nsec, old_page_owner->pid, @@ -391,7 +387,7 @@ void __folio_copy_owner(struct folio *newfolio, struct = folio *old) * will be freed after migration. Keep them until then as they may be * useful. */ - __update_page_owner_free_handle(new_ext, 0, old_page_owner->order, + __update_page_owner_free_handle(&newfolio->page, 0, old_page_owner->order, old_page_owner->free_pid, old_page_owner->free_tgid, old_page_owner->free_ts_nsec); @@ -400,11 +396,12 @@ void __folio_copy_owner(struct folio *newfolio, struc= t folio *old) * for the new one and the old folio otherwise there will be an imbalance * when subtracting those pages from the stack. */ - for (i =3D 0; i < (1 << new_page_owner->order); i++) { + rcu_read_lock(); + for_each_page_ext(&old->page, 1 << new_page_owner->order, page_ext, iter)= { + old_page_owner =3D get_page_owner(page_ext); old_page_owner->handle =3D migrate_handle; - old_ext =3D page_ext_next(old_ext); - old_page_owner =3D get_page_owner(old_ext); } + rcu_read_unlock(); =20 page_ext_put(new_ext); page_ext_put(old_ext); @@ -813,7 +810,7 @@ static void init_pages_in_zone(pg_data_t *pgdat, struct= zone *zone) goto ext_put_continue; =20 /* Found early allocated page */ - __update_page_owner_handle(page_ext, early_handle, 0, 0, + __update_page_owner_handle(page, early_handle, 0, 0, -1, local_clock(), current->pid, current->tgid, current->comm); count++; --=20 2.48.1