On Mon, Nov 24 2025, Pratyush Yadav wrote: > On Mon, Nov 24 2025, [email protected] wrote: > >> From: Ran Xiaokai <[email protected]> >> >> When booting with debug_pagealloc=on while having: >> CONFIG_KEXEC_HANDOVER_ENABLE_DEFAULT=y >> CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF=n >> the system fails to boot due to page faults during kmemleak scanning. >> >> This occurs because: >> With debug_pagealloc is enabled, __free_pages() invokes >> debug_pagealloc_unmap_pages(), clearing the _PAGE_PRESENT bit for >> freed pages in the kernel page table. >> KHO scratch areas are allocated from memblock and noted by kmemleak. But >> these areas don't remain reserved but released later to the page allocator >> using init_cma_reserved_pageblock(). This causes subsequent kmemleak scans >> access non-PRESENT pages, leading to fatal page faults. >> >> Mark scratch areas with kmemleak_ignore_phys() after they are allocated >> from memblock to exclude them from kmemleak scanning before they are >> released to buddy allocator to fix this. >> >> Fixes: 3dc92c311498 ("kexec: add Kexec HandOver (KHO) generation helpers") >> Signed-off-by: Ran Xiaokai <[email protected]> >> Reviewed-by: Mike Rapoport (Microsoft) <[email protected]> >> --- >> kernel/liveupdate/kexec_handover.c | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/kernel/liveupdate/kexec_handover.c >> b/kernel/liveupdate/kexec_handover.c >> index 224bdf5becb6..c729d455ee7b 100644 >> --- a/kernel/liveupdate/kexec_handover.c >> +++ b/kernel/liveupdate/kexec_handover.c >> @@ -11,6 +11,7 @@ >> >> #include <linux/cleanup.h> >> #include <linux/cma.h> >> +#include <linux/kmemleak.h> >> #include <linux/count_zeros.h> >> #include <linux/kexec.h> >> #include <linux/kexec_handover.h> >> @@ -1369,6 +1370,7 @@ static __init int kho_init(void) >> unsigned long count = kho_scratch[i].size >> PAGE_SHIFT; >> unsigned long pfn; >> >> + kmemleak_ignore_phys(kho_scratch[i].addr); > > Can you please put the explanation you gave in [0] for why this is not > necessary in KHO boot as a comment here?
And also an explanation of why this is necessary in the first place. You do explain that in the commit message, but a shorter version as a comment will make this a lot easier to understand instead of having to dig through git history. [...] -- Regards, Pratyush Yadav
