Hi Guanyou,

Just a reminder that please don't send the patches as the form of
email attachments. Please send it via commands like: "git send-email
--to=<...> HEAD~2", such that people can do inline commenting on your
code.

Other than that, the patch LGTM, so ack patch 1 & 2.

Thanks,
Tao Liu

On Fri, Dec 5, 2025 at 7:02 PM Guanyou Chen <chenguanyou9338@gmail.com> wrote:
>
> Hi Tao
>
> attached split 2 patches.
>
> Thanks
> Guanyou
>
>
> Tao Liu <ltao@redhat.com> 于2025年12月5日周五 11:31写道：
>>
>> Hi Guanyou,
>>
>> On Fri, Dec 5, 2025 at 3:03 PM Guanyou Chen <chenguanyou9338@gmail.com> wrote:
>> >
>> > Hi Tao,
>> >
>> > Check swap_file_is_file from crash commit 3452fe802bf94
>> > ("Fix "kmem -i" and "swap" commands on Linux 6.10-rc1 and later kernels")
>> >
>> > Thanks,
>> > Guanyou
>> >
>> > Tao Liu <ltao@redhat.com> 于2025年12月5日周五 06:40写道：
>> >>
>> >> Hi Guanyou,
>> >>
>> >> On Thu, Dec 4, 2025 at 11:33 PM Guanyou Chen <chenguanyou9338@gmail.com> wrote:
>> >> >
>> >> > Hi Lianbo
>> >> >
>> >> > Kernel commit 55564814a838 ("arm64/mm: Move PTE_PRESENT_INVALID
>> >> > to overlay PTE_NG"), which is contained in Linux 6.10 and
>> >> > later kernels, changed the format of swap entries on arm64.
>> >> > Without the patch, the "vtop" command cannot display swap information
>> >> >
>> >> > before:
>> >> >     crash> vtop 2000000
>> >> >     VIRTUAL     PHYSICAL
>> >> >     2000000     (not mapped)
>> >> >
>> >> >     PAGE DIRECTORY: ffffff8106356000
>> >> >        PGD: ffffff8106356000 => 800000186355003
>> >> >        PMD: ffffff8106355080 => 8000001476f5003
>> >> >        PTE: ffffff80c76f5000 => 101a62004
>> >> >
>> >> >        PTE       OFFSET: 1055330
>> >> >     vtop: cannot determine swap location
>> >> >
>> >> > without the patch:
>> >> >     crash> vtop 2000000
>> >> >     VIRTUAL     PHYSICAL
>> >> >     2000000     (not mapped)
>> >> >
>> >> >     PAGE DIRECTORY: ffffff8106356000
>> >> >        PGD: ffffff8106356000 => 800000186355003
>> >> >        PMD: ffffff8106355080 => 8000001476f5003
>> >> >        PTE: ffffff80c76f5000 => 101a62004
>> >> >
>> >> >        PTE                     SWAP                  OFFSET
>> >> >     101a62004  /first_stage_ramdisk/dev/block/zram0  1055330
>> >> >
>> >> >           VMA           START       END     FLAGS FILE
>> >> >     ffffff81a06e8b00    2000000   22000000 100073
>> >> >
>> >> >     SWAP: /first_stage_ramdisk/dev/block/zram0  OFFSET: 1055330
>> >> >
>> >> > Link: https://lore.kernel.org/r/20240503144604.151095-4-ryan.roberts@arm.com
>> >> > Signed-off-by: Guanyou.Chen <chenguanyou@xiaomi.com>
>> >> > ---
>> >> >  arm64.c  | 11 ++++++++++-
>> >> >  memory.c |  5 ++++-
>> >> >  2 files changed, 14 insertions(+), 2 deletions(-)
>> >> >
>> >> > diff --git a/arm64.c b/arm64.c
>> >> > index 1723595..c125655 100644
>> >> > --- a/arm64.c
>> >> > +++ b/arm64.c
>> >> > @@ -712,7 +712,16 @@ arm64_init(int when)
>> >> >             }
>> >> >         }
>> >> >
>> >> > -       if (THIS_KERNEL_VERSION >= LINUX(5,19,0)) {
>> >> > +       if (THIS_KERNEL_VERSION >= LINUX(6,10,0)) {
>> >> > +           ms->__SWP_TYPE_BITS = 5;
>> >> > +           ms->__SWP_TYPE_SHIFT = 6;
>> >> > +           ms->__SWP_TYPE_MASK = ((1UL << ms->__SWP_TYPE_BITS) - 1);
>> >> > +           ms->__SWP_OFFSET_SHIFT = 12;
>> >> > +           ms->__SWP_OFFSET_BITS = 50;
>> >> > +           ms->__SWP_OFFSET_MASK = ((1UL << ms->__SWP_OFFSET_BITS) - 1);
>> >> > +           ms->PTE_PROT_NONE = 0; /* unused */
>> >> > +           ms->PTE_FILE = 0;  /* unused */
>> >> > +       } else if (THIS_KERNEL_VERSION >= LINUX(5,19,0)) {
>>
>> Sorry maybe I didn't make myself clear. What I mean is, the kernel
>> link, aka https://lore.kernel.org/r/20240503144604.151095-4-ryan.roberts@arm.com,
>> updated the information as you have addressed above, and this part is
>> OK to me.
>>
>> >> >             ms->__SWP_TYPE_BITS = 5;
>> >> >             ms->__SWP_TYPE_SHIFT = 3;
>> >> >             ms->__SWP_TYPE_MASK = ((1UL << ms->__SWP_TYPE_BITS) - 1);
>> >> > diff --git a/memory.c b/memory.c
>> >> > index 400d31a..cbc8d2f 100644
>> >> > --- a/memory.c
>> >> > +++ b/memory.c
>> >> > @@ -16415,6 +16415,8 @@ get_swapdev(ulong type, char *buf)
>> >> >     ulong vfsmnt;
>> >> >     char *devname;
>> >> >     char buf1[BUFSIZE];
>> >> > +   int swap_file_is_file =
>> >> > +       STREQ(MEMBER_TYPE_NAME("swap_info_struct", "swap_file"), "file");
>> >> >
>> >> >     swap_info_init();
>> >> >
>> >> > @@ -16474,7 +16476,8 @@ get_swapdev(ulong type, char *buf)
>> >> >             vfsmnt = ULONG(vt->swap_info_struct +
>> >> >                 OFFSET(swap_info_struct_swap_vfsmnt));
>> >> >                 get_pathname(swap_file, buf, BUFSIZE, 1, vfsmnt);
>> >> > -                } else if (VALID_MEMBER (swap_info_struct_old_block_size)) {
>> >> > +                } else if (VALID_MEMBER (swap_info_struct_old_block_size)
>> >> > +                   || swap_file_is_file) {
>>
>> But the link nor your commit log doesn't provide information for the
>> above swap_file_is_file code change. Like why do you need to add the
>> "|| swap_file_is_file" check here? Does it have any relations with the
>> previous __SWP_TYPE_XXX value updating? What I'm trying to figure out
>> is whether your __SWP_TYPE_XXX updating and swap_file_is_file
>> checking, are independent of each other and should go into 2 seperated
>> patches.
>>
>> >>
>> >> Any reason for the extra swap_file_is_file check? From the kernel
>> >> patch link you posted, only the __SWP_TYPE_XXX changes, which is
>> >> presented in (THIS_KERNEL_VERSION >= LINUX(6,10,0), but no info
>> >> related to swap_file_is_file check?
>> >>
>> >> Thanks,
>> >> Tao Liu
>> >>
>> >>
>> >> >             devname = vfsmount_devname(file_to_vfsmnt(swap_file),
>> >> >                 buf1, BUFSIZE);
>> >> >             get_pathname(file_to_dentry(swap_file),
>> >> > --
>> >> > 2.34.1
>> >> >
>> >> > Thanks.
>> >> > Guanyou
>> >>
>>