On Thu, Dec 18, 2025 at 07:49:11PM -0500, Pasha Tatashin wrote: > On Thu, Dec 18, 2025 at 7:23 PM Pasha Tatashin > <[email protected]> wrote: > > > > If the previous kernel enabled KHO but did not call kho_finalize() > > (e.g., CONFIG_LIVEUPDATE=n or userspace skipped the finalization step), > > the 'preserved-memory-map' property in the FDT remains empty/zero. > > > > Previously, kho_populate() would succeed regardless of the memory map's > > state, reserving the incoming scratch regions in memblock. However, > > kho_memory_init() would later fail to deserialize the empty map. By that > > time, the scratch regions were already registered, leading to partial > > initialization and subsequent list corruption (double-free) during > > kho_init(). > > > > Move the validation of the preserved memory map earlier into > > kho_populate(). If the memory map is empty/NULL: > > 1. Abort kho_populate() immediately with -ENOENT. > > 2. Do not register or reserve the incoming scratch memory, allowing the new > > kernel to reclaim those pages as standard free memory. > > 3. Leave the global 'kho_in' state uninitialized. > > > > Consequently, kho_memory_init() sees no active KHO context > > (kho_in.mem_chunks is NULL) and falls back to kho_reserve_scratch(), > > allocating fresh scratch memory as if it were a standard cold boot. > > > > Fixes: de51999e687c ("kho: allow memory preservation state updates after > > finalization") > > Reported-by: Ricardo <[email protected]> > > Closes: > > https://lore.kernel.org/all/[email protected] > > Signed-off-by: Pasha Tatashin <[email protected]> > > --- > > kernel/liveupdate/kexec_handover.c | 36 +++++++++++++++++------------- > > 1 file changed, 21 insertions(+), 15 deletions(-) > > > > diff --git a/kernel/liveupdate/kexec_handover.c > > b/kernel/liveupdate/kexec_handover.c > > index 9dc51fab604f..96c708f753d4 100644 > > --- a/kernel/liveupdate/kexec_handover.c > > +++ b/kernel/liveupdate/kexec_handover.c > > @@ -460,10 +460,9 @@ static void __init deserialize_bitmap(unsigned int > > order, > > } > > } > > > > -/* Return true if memory was deserizlied */ > > -static bool __init kho_mem_deserialize(const void *fdt) > > +/* Returns head of preserved physical memory chunks pointer from FDT */ > > +static struct khoser_mem_chunk * __init kho_get_mem_chunks(const void *fdt) > > { > > - struct khoser_mem_chunk *chunk; > > const void *mem_ptr; > > u64 mem; > > int len; > > @@ -471,16 +470,16 @@ static bool __init kho_mem_deserialize(const void > > *fdt) > > mem_ptr = fdt_getprop(fdt, 0, PROP_PRESERVED_MEMORY_MAP, &len); > > if (!mem_ptr || len != sizeof(u64)) { > > pr_err("failed to get preserved memory bitmaps\n"); > > - return false; > > + return NULL; > > } > > > > mem = get_unaligned((const u64 *)mem_ptr); > > - chunk = mem ? phys_to_virt(mem) : NULL; > > > > - /* No preserved physical pages were passed, no deserialization */ > > - if (!chunk) > > - return false; > > + return mem ? phys_to_virt(mem) : NULL; > > I need to update this patch, phys_to_virt() should not be called from > kho_populate() before KASLR is initialized. This causes a problem with > my live update test. I will send a new version soon.
Thanks for the patch Pasha! FWIW, I no longer see the issue I reported. I will test your v2 when posted. BR, Ricardo > > Pasha
