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 <[email protected]> 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 <[email protected]>
> 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/[email protected]
> > Signed-off-by: Guanyou.Chen <[email protected]>
> > ---
> > 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)) {
> > 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) {
>
> 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
>
>
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