>On Thu, Nov 20, 2025 at 02:41:47PM +0000, [email protected] wrote: >> Subject: liveupdate: Fix boot failure due to kmemleak access to unmapped >> pages > >Please prefix kexec handover patches with kho: rather than liveupdate.
Thanks for your review, i will update the patch subject. >> 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 enabled, __free_pages() invokes >> debug_pagealloc_unmap_pages(), clearing the _PAGE_PRESENT bit for >> freed pages in the direct mapping. >> Commit 3dc92c311498 ("kexec: add Kexec HandOver (KHO) generation helpers") >> releases the KHO scratch region via init_cma_reserved_pageblock(), >> unmapping its physical pages. Subsequent kmemleak scanning accesses >> these unmapped pages, triggering fatal page faults. >> >> Call kmemleak_no_scan_phys() from kho_reserve_scratch() to >> exclude the reserved region from scanning before >> it is released to the buddy allocator. >> >> Fixes: 3dc92c311498 ("kexec: add Kexec HandOver (KHO) generation helpers") >> Signed-off-by: Ran Xiaokai <[email protected]> >> --- >> kernel/liveupdate/kexec_handover.c | 4 ++++ >> 1 file changed, 4 insertions(+) >> >> diff --git a/kernel/liveupdate/kexec_handover.c >> b/kernel/liveupdate/kexec_handover.c >> index 224bdf5becb6..dd4942d1d76c 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> >> @@ -654,6 +655,7 @@ static void __init kho_reserve_scratch(void) >> if (!addr) >> goto err_free_scratch_desc; >> >> + kmemleak_no_scan_phys(addr); > >There's kmemleak_ignore_phys() that can be called after the scratch areas >allocated from memblock and with that kmemleak should not access them. > >Take a look at __cma_declare_contiguous_nid(). Thanks for catching this. Since kmemleak_ignore_phys() perfectly handles this issue, introducing another helper is unnecessary. I'll post v2 shortly. >> kho_scratch[i].addr = addr; >> kho_scratch[i].size = size; >> i++; > >-- >Sincerely yours, >Mike.
