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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> X-Rspam-User: X-Stat-Signature: iazhyxdcd5iqzbaxqhd51r9yhsenkhmz X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: B9CA2C000D X-HE-Tag: 1690613942-886013 X-HE-Meta: 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 4ojAFo7J qWzH5GfrG1u3+9KpXc20Z44LumQ55VDhgrQ+cQwKSSvChjmZM3DxeaOb4AbFDIgSbim4YRfOiMLYLIJNhtJM+rD+KRNmCDuCEx+8YRrHxodr0NNP1LvWEJp+j+jpxeI7jbd/EU2l2zjvWiCztTLlihJlSHfNbCVqd0g0DM8su9vmxQ0GS4S3BTdeBx1Blz0mdY59tOR0p2BVobhaaAcK1fpR0Tsor7A/8u6Vo8A2x7pU0IozWYccHKWsD+etEkwYJM8zziy2jD9U6fDwkQgs7t0Ic7ypEjL2m42/hCJYLpamwamM5lheP67cocy08yViY7yYGiUgRJQPapYR6tor+kbmJxH5WjRqG4pZKoqeyzp693flpWJneeBwixLenewTj9bCSngErqnCgQYo= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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.