[Crash-utility] Re: [PATCH] arm64: Fix "vtop" command to display swap information on Linux 6.10 and later

Hi Guanyou, On Fri, Dec 5, 2025 at 3:03 PM Guanyou Chen <chenguanyou9338(a)gmail.com&gt; 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(a)redhat.com&gt; 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(a)gmail.com&gt; 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(a)xiaomi.com&gt; >> > --- >> > 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 >>