linux-kernel - Re: [PATCH] memblock: Introduce memblock_reserve

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Message-ID: <20230627143318.GN52412@kernel.org>
Date:   Tue, 27 Jun 2023 17:33:18 +0300
From:   Mike Rapoport <rppt@...nel.org>
To:     Yajun Deng <yajun.deng@...ux.dev>
Cc:     akpm@...ux-foundation.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] memblock: Introduce memblock_reserve_node()

On Tue, Jun 27, 2023 at 12:13:16AM +0000, Yajun Deng wrote:
> June 26, 2023 2:21 PM, "Mike Rapoport" <rppt@...nel.org> wrote:
> 
> > On Sun, Jun 25, 2023 at 07:39:10AM +0000, Yajun Deng wrote:
> > 
> >> June 25, 2023 1:08 PM, "Mike Rapoport" <rppt@...nel.org> wrote:
> >> 
> >> On Sat, Jun 24, 2023 at 10:46:22AM +0800, Yajun Deng wrote:
> >> 
> >> It only returns address now in memblock_find_in_range_node(), we can add a
> >> parameter pointing to integer for node id of the range, which can be used
> >> to pass the node id to the new reserve region.
> >> 
> >> Introduce memblock_reserve_node() so that the node id can be passed to
> >> the reserve region in memblock_alloc_range_nid().
> >> 
> >> Signed-off-by: Yajun Deng <yajun.deng@...ux.dev>
> >> 
> >> What problem does this patch solve?
> >> 
> >> If we set nid and flags in memblock_alloc_range_nid(), we may not need
> >> memblock_set_node() in memmap_init_reserved_pages().
> > 
> > When memblock_reserve() is called before NUMA setup, the node ids are still
> > unset in memblock.memory, so very early reservations will be missed and we
> > still have to update node ids in memblock.reserved later.
> 
> Even so, we still need to pass the 'flags' to the new reserve region.
> choose_memblock_flags() may return MEMBLOCK_MIRROR in memblock_alloc_range_nid(),
> memblock_reserve() couldn't pass this flag in this case.
 
flags are only relevant to memblock.memory, we don't care about the flags
in memblock.reserved.
 
> >> I tested this patch and delete memblock_set_node() in memmap_init_reserved_pages().
> >> It works fine. I did not delete memblock_set_node() in this patch just in case.
> > 
> > --
> > Sincerely yours,
> > Mike.

-- 
Sincerely yours,
Mike.