linux-kernel - Re: [v3 3/4] memblock: introduce MEMBLOCK_RSRV_NOINIT

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <357EEE41-1898-4430-BCC7-73F591CE8749@linux.dev>
Date:   Mon, 28 Aug 2023 15:26:17 +0800
From:   Muchun Song <muchun.song@...ux.dev>
To:     Usama Arif <usama.arif@...edance.com>
Cc:     Linux-MM <linux-mm@...ck.org>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Mike Rapoport <rppt@...nel.org>, linux-kernel@...r.kernel.org,
        Muchun Song <songmuchun@...edance.com>,
        fam.zheng@...edance.com, liangma@...ngbit.com,
        punit.agrawal@...edance.com
Subject: Re: [v3 3/4] memblock: introduce MEMBLOCK_RSRV_NOINIT_VMEMMAP flag



> On Aug 25, 2023, at 19:18, Usama Arif <usama.arif@...edance.com> 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 <usama.arif@...edance.com>

Reviewed-by: Muchun Song <songmuchun@...edance.com>

One nit below.

> ---
> include/linux/memblock.h | 10 ++++++++++
> mm/memblock.c            | 32 +++++++++++++++++++++++++++-----
> 2 files changed, 37 insertions(+), 5 deletions(-)
> 
> diff --git a/include/linux/memblock.h b/include/linux/memblock.h
> index f71ff9f0ec81..6d681d053880 100644
> --- a/include/linux/memblock.h
> +++ b/include/linux/memblock.h
> @@ -40,6 +40,8 @@ extern unsigned long long max_possible_pfn;
>  * via a driver, and never indicated in the firmware-provided memory map as
>  * system RAM. This corresponds to IORESOURCE_SYSRAM_DRIVER_MANAGED in the
>  * kernel resource tree.
> + * @MEMBLOCK_RSRV_NOINIT_VMEMMAP: memory region for which struct pages are
> + * not initialized (only for reserved regions).

We have a more detailed explanation here.

>  */
> enum memblock_flags {
> 	MEMBLOCK_NONE = 0x0, /* No special request */
> @@ -47,6 +49,8 @@ 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 */
> +	/* don't initialize struct pages associated with this reserver memory block */

Those comments right after the macros here seem like a brief explanation.
To keep the consistent with others, maybe "don't initialize struct pages"
is enough? At least, a detailed one is redundant and repetitive compared
with the above one.

> +	MEMBLOCK_RSRV_NOINIT_VMEMMAP = 0x10,
> };