linux-kernel - Re: [PATCH] mm/migrate_device: Try to handle swapcache pages.

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: <87wn1ja793.fsf@yhuang6-desk2.ccr.corp.intel.com>
Date:   Mon, 08 May 2023 10:26:16 +0800
From:   "Huang, Ying" <ying.huang@...el.com>
To:     mpenttil@...hat.com
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        apopple@...dia.com, jhubbard@...dia.com, rcampbell@...dia.com
Subject: Re: [PATCH] mm/migrate_device: Try to handle swapcache pages.

mpenttil@...hat.com writes:

> From: Mika Penttilä <mpenttil@...hat.com>
>
> Migrating file pages and swapcache pages into device memory is not supported.
> The decision is done based on page_mapping(). For now, swapcache pages are not migrated.
>
> Things can however be improved, for swapcache pages. Try to get rid of the swap cache,
> and if successful, go ahead as with other anonymous pages.
>
> As a detail, do not mess with shmem pages, as they handle swap internally.
>
> Cc: Alistair Popple <apopple@...dia.com>
> Cc: John Hubbard <jhubbard@...dia.com>
> Cc: Ralph Campbell <rcampbell@...dia.com>
> Signed-off-by: Mika Penttilä <mpenttil@...hat.com>
> ---
>  mm/migrate_device.c | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/mm/migrate_device.c b/mm/migrate_device.c
> index d30c9de60b0d..e8169c58c341 100644
> --- a/mm/migrate_device.c
> +++ b/mm/migrate_device.c
> @@ -12,6 +12,7 @@
>  #include <linux/mmu_notifier.h>
>  #include <linux/oom.h>
>  #include <linux/pagewalk.h>
> +#include <linux/shmem_fs.h>
>  #include <linux/rmap.h>
>  #include <linux/swapops.h>
>  #include <asm/tlbflush.h>
> @@ -750,10 +751,17 @@ static void __migrate_device_pages(unsigned long *src_pfns,
>  			/*
>  			 * For now only support anonymous memory migrating to
>  			 * device private or coherent memory.
> +			 *
> +			 * Try to get rid of swap cache if possible.
> +			 * Leave shmem pages alone, they handle swap internally
> +			 *
>  			 */
>  			if (mapping) {
> -				src_pfns[i] &= ~MIGRATE_PFN_MIGRATE;
> -				continue;
> +				if (shmem_mapping(mapping) ||
> +				    !folio_free_swap(page_folio(page))) {

Should we filter out file pages firstly?

> +					src_pfns[i] &= ~MIGRATE_PFN_MIGRATE;
> +					continue;
> +				}
>  			}
>  		} else if (is_zone_device_page(newpage)) {
>  			/*

Best Regards,
Huang, Ying