From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7CFADC001DF for ; Sat, 29 Jul 2023 06:59:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235931AbjG2G7G (ORCPT ); Sat, 29 Jul 2023 02:59:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39558 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229685AbjG2G7D (ORCPT ); Sat, 29 Jul 2023 02:59:03 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5B7FC4211 for ; Fri, 28 Jul 2023 23:59:02 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id DC2116068C for ; Sat, 29 Jul 2023 06:59:01 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 09C40C433C8; Sat, 29 Jul 2023 06:58:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1690613941; bh=MQ5sX5BNVLtCUJ5SoZaQ2/ejVdHwvmb5bb41ld3hbAw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=TOv3AI7l4GXLDwbgcI5zIbdmjg8k8wNj1IsITudj8j6uVtJEqAAKSlzMGr/5Xr8Sn MeiCoDjZe9pNSmuVZVt4g/Da1qhUZs35j3l2MVV7ly1b+rAdc9PFsfc6H6PJFLYsxS 2UJPj46MmitJCclymRUGkWtjybclbT5tAv3a8I76gVS5rXyFuUJ7FUW26nGfYDKdUL 63lHSXBkTT0dETSvyD0J8DU8fVQ1QTtmqvDSpU5jkr2Hw0BxjGsHgjHVdAMsvnE//1 9nXjyBqPxMqgPNHcqnDLhWoDd4H2lrHm9nn8U3FfjkRYgNXmWjwj6xsXJYodr+wQBS HeHEVV/3dVD/w== Date: Sat, 29 Jul 2023 09:58:22 +0300 From: Mike Rapoport To: Usama Arif Cc: linux-mm@kvack.org, muchun.song@linux.dev, mike.kravetz@oracle.com, linux-kernel@vger.kernel.org, fam.zheng@bytedance.com, liangma@liangbit.com, simon.evans@bytedance.com, punit.agrawal@bytedance.com Subject: Re: [v1 4/6] memblock: introduce MEMBLOCK_RSRV_NOINIT flag Message-ID: <20230729065822.GF1901145@kernel.org> References: <20230727204624.1942372-1-usama.arif@bytedance.com> <20230727204624.1942372-5-usama.arif@bytedance.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230727204624.1942372-5-usama.arif@bytedance.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 27, 2023 at 09:46:22PM +0100, Usama Arif wrote: > For reserved memory regions marked with this flag, > reserve_bootmem_region is not called during memmap_init_reserved_pages. > This can be used to avoid struct page initialization for > regions which won't need them, for e.g. hugepages with > HVO enabled. > > Signed-off-by: Usama Arif > --- > include/linux/memblock.h | 7 +++++++ > mm/memblock.c | 32 ++++++++++++++++++++++++++------ > 2 files changed, 33 insertions(+), 6 deletions(-) > > diff --git a/include/linux/memblock.h b/include/linux/memblock.h > index f71ff9f0ec81..7f9d06c08592 100644 > --e a/include/linux/memblock.h > +++ b/include/linux/memblock.h > @@ -47,6 +47,7 @@ enum memblock_flags { > MEMBLOCK_MIRROR = 0x2, /* mirrored region */ > MEMBLOCK_NOMAP = 0x4, /* don't add to kernel direct mapping */ > MEMBLOCK_DRIVER_MANAGED = 0x8, /* always detected via a driver */ > + MEMBLOCK_RSRV_NOINIT = 0x10, /* don't call reserve_bootmem_region for this region */ The comment should reflect what it does, not how. > }; > > /** > @@ -125,6 +126,7 @@ int memblock_clear_hotplug(phys_addr_t base, phys_addr_t size); > int memblock_mark_mirror(phys_addr_t base, phys_addr_t size); > int memblock_mark_nomap(phys_addr_t base, phys_addr_t size); > int memblock_clear_nomap(phys_addr_t base, phys_addr_t size); > +int memblock_rsrv_mark_noinit(phys_addr_t base, phys_addr_t size); Please spell out reserved here. > void memblock_free_all(void); > void memblock_free(void *ptr, size_t size); > @@ -259,6 +261,11 @@ static inline bool memblock_is_nomap(struct memblock_region *m) > return m->flags & MEMBLOCK_NOMAP; > } > > +static inline bool memblock_is_noinit(struct memblock_region *m) > +{ > + return m->flags & MEMBLOCK_RSRV_NOINIT; > +} > + > static inline bool memblock_is_driver_managed(struct memblock_region *m) > { > return m->flags & MEMBLOCK_DRIVER_MANAGED; > diff --git a/mm/memblock.c b/mm/memblock.c > index 4fd431d16ef2..3a15708af3b6 100644 > --- a/mm/memblock.c > +++ b/mm/memblock.c > @@ -997,6 +997,22 @@ int __init_memblock memblock_clear_nomap(phys_addr_t base, phys_addr_t size) > return memblock_setclr_flag(base, size, 0, MEMBLOCK_NOMAP, 0); > } > > +/** > + * memblock_rsrv_mark_noinit - Mark a reserved memory region with flag MEMBLOCK_RSRV_NOINIT. > + * @base: the base phys addr of the region > + * @size: the size of the region > + * > + * For memory regions marked with %MEMBLOCK_RSRV_NOINIT, reserve_bootmem_region > + * is not called during memmap_init_reserved_pages, hence struct pages are not > + * initialized for this region. Here as well, the part of how is much less important. Here you should emphasize that struct pages for MEMBLOCK_RSRV_NOINIT regions are not initialized. > + * > + * Return: 0 on success, -errno on failure. > + */ > +int __init_memblock memblock_rsrv_mark_noinit(phys_addr_t base, phys_addr_t size) > +{ > + return memblock_setclr_flag(base, size, 1, MEMBLOCK_RSRV_NOINIT, 1); > +} > + > static bool should_skip_region(struct memblock_type *type, > struct memblock_region *m, > int nid, int flags) > @@ -2113,13 +2129,17 @@ static void __init memmap_init_reserved_pages(void) > memblock_set_node(start, end, &memblock.reserved, nid); > } > > - /* initialize struct pages for the reserved regions */ > + /* > + * initialize struct pages for reserved regions that don't have > + * the MEMBLOCK_RSRV_NOINIT flag set > + */ > for_each_reserved_mem_region(region) { > - nid = memblock_get_region_node(region); > - start = region->base; > - end = start + region->size; > - > - reserve_bootmem_region(start, end, nid); > + if (!memblock_is_noinit(region)) { > + nid = memblock_get_region_node(region); > + start = region->base; > + end = start + region->size; Please keep the empty line here > + reserve_bootmem_region(start, end, nid); > + } > } > } > > -- > 2.25.1 > -- Sincerely yours, Mike.