6.18-stable review patch. If anyone has any objections, please let me know.
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From: Sourabh Jain sourabhjain@linux.ibm.com
[ Upstream commit 7afe2383eff05f76f4ce2cfda658b7889c89f101 ]
The elfcorehdr segment in the kdump image stores information about the memory regions (called crash memory ranges) that the kdump kernel must capture.
When a memory hot-remove event occurs, the kernel regenerates the elfcorehdr for the currently loaded kdump image to remove the hot-removed memory from the crash memory ranges.
Call chain: remove_mem_range() update_crash_elfcorehdr() arch_crash_handle_hotplug_event() crash_handle_hotplug_event()
While removing the hot-removed memory from the crash memory ranges in remove_mem_range(), if the removed memory lies within an existing crash range, that range is split into two. During this split, the size of the second range was being calculated incorrectly.
This leads to dump capture failure with makedumpfile with below error:
$ makedumpfile -l -d 31 /proc/vmcore /tmp/vmcore
readpage_elf: Attempt to read non-existent page at 0xbbdab0000. readmem: type_addr: 0, addr:c000000bbdab7f00, size:16 validate_mem_section: Can't read mem_section array. readpage_elf: Attempt to read non-existent page at 0xbbdab0000. readmem: type_addr: 0, addr:c000000bbdab7f00, size:8 get_mm_sparsemem: Can't get the address of mem_section.
The updated crash memory range in PT_LOAD entry is holding incorrect data (checkout FileSiz and MemSiz):
readelf -a /proc/vmcore <snip...> Type Offset VirtAddr PhysAddr FileSiz MemSiz Flags Align LOAD 0x0000000b013d0000 0xc000000b80000000 0x0000000b80000000 0xffffffffc0000000 0xffffffffc0000000 RWE 0x0 <snip...>
Update the size calculation for the new crash memory range to fix this issue.
Note: This problem will not occur if the kdump kernel is loaded or reloaded after a memory hot-remove operation.
Fixes: 849599b702ef ("powerpc/crash: add crash memory hotplug support") Reported-by: Shirisha G shirisha@linux.ibm.com Signed-off-by: Sourabh Jain sourabhjain@linux.ibm.com Signed-off-by: Madhavan Srinivasan maddy@linux.ibm.com Link: https://patch.msgid.link/20251105033941.1752287-1-sourabhjain@linux.ibm.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/powerpc/kexec/ranges.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/powerpc/kexec/ranges.c b/arch/powerpc/kexec/ranges.c index 3702b0bdab141..426bdca4667e7 100644 --- a/arch/powerpc/kexec/ranges.c +++ b/arch/powerpc/kexec/ranges.c @@ -697,8 +697,8 @@ int remove_mem_range(struct crash_mem **mem_ranges, u64 base, u64 size) * two half. */ else { + size = mem_rngs->ranges[i].end - end + 1; mem_rngs->ranges[i].end = base - 1; - size = mem_rngs->ranges[i].end - end; ret = add_mem_range(mem_ranges, end + 1, size); } }