kernel/arch/powerpc/kexec, branch linux-rolling-stable

powerpc/crash: adjust the elfcorehdr size

2026-03-19T15:14:45Z

[ Upstream commit 04e707cb77c272cb0bb2e2e3c5c7f844d804a089 ] With crash hotplug support enabled, additional memory is allocated to the elfcorehdr kexec segment to accommodate resources added during memory hotplug events. However, the kdump FDT is not updated with the same size, which can result in elfcorehdr corruption in the kdump kernel. Update elf_headers_sz (the kimage member representing the size of the elfcorehdr kexec segment) to reflect the total memory allocated for the elfcorehdr segment instead of the elfcorehdr buffer size at the time of kdump load. This allows of_kexec_alloc_and_setup_fdt() to reserve the full elfcorehdr memory in the kdump FDT and prevents elfcorehdr corruption. Fixes: 849599b702ef8 ("powerpc/crash: add crash memory hotplug support") Reviewed-by: Hari Bathini Signed-off-by: Sourabh Jain Signed-off-by: Madhavan Srinivasan Link: https://patch.msgid.link/20260227171801.2238847-1-sourabhjain@linux.ibm.com Signed-off-by: Sasha Levin

powerpc/kexec/core: use big-endian types for crash variables

2026-03-19T15:14:45Z

[ Upstream commit 20197b967a6a29dab81495f25a988515bda84cfe ] Use explicit word-sized big-endian types for kexec and crash related variables. This makes the endianness unambiguous and avoids type mismatches that trigger sparse warnings. The change addresses sparse warnings like below (seen on both 32-bit and 64-bit builds): CHECK ../arch/powerpc/kexec/core.c sparse: expected unsigned int static [addressable] [toplevel] [usertype] crashk_base sparse: got restricted __be32 [usertype] sparse: warning: incorrect type in assignment (different base types) sparse: expected unsigned int static [addressable] [toplevel] [usertype] crashk_size sparse: got restricted __be32 [usertype] sparse: warning: incorrect type in assignment (different base types) sparse: expected unsigned long long static [addressable] [toplevel] mem_limit sparse: got restricted __be32 [usertype] sparse: warning: incorrect type in assignment (different base types) sparse: expected unsigned int static [addressable] [toplevel] [usertype] kernel_end sparse: got restricted __be32 [usertype] No functional change intended. Fixes: ea961a828fe7 ("powerpc: Fix endian issues in kexec and crash dump code") Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202512221405.VHPKPjnp-lkp@intel.com/ Signed-off-by: Sourabh Jain Tested-by: Venkat Rao Bagalkote Signed-off-by: Madhavan Srinivasan Link: https://patch.msgid.link/20251224151257.28672-1-sourabhjain@linux.ibm.com Signed-off-by: Sasha Levin

powerpc/kexec: Enable SMT before waking offline CPUs

2025-12-22T12:23:37Z

If SMT is disabled or a partial SMT state is enabled, when a new kernel image is loaded for kexec, on reboot the following warning is observed: kexec: Waking offline cpu 228. WARNING: CPU: 0 PID: 9062 at arch/powerpc/kexec/core_64.c:223 kexec_prepare_cpus+0x1b0/0x1bc [snip] NIP kexec_prepare_cpus+0x1b0/0x1bc LR kexec_prepare_cpus+0x1a0/0x1bc Call Trace: kexec_prepare_cpus+0x1a0/0x1bc (unreliable) default_machine_kexec+0x160/0x19c machine_kexec+0x80/0x88 kernel_kexec+0xd0/0x118 __do_sys_reboot+0x210/0x2c4 system_call_exception+0x124/0x320 system_call_vectored_common+0x15c/0x2ec This occurs as add_cpu() fails due to cpu_bootable() returning false for CPUs that fail the cpu_smt_thread_allowed() check or non primary threads if SMT is disabled. Fix the issue by enabling SMT and resetting the number of SMT threads to the number of threads per core, before attempting to wake up all present CPUs. Fixes: 38253464bc82 ("cpu/SMT: Create topology_smt_thread_allowed()") Reported-by: Sachin P Bappalige Cc: stable@vger.kernel.org # v6.6+ Reviewed-by: Srikar Dronamraju Signed-off-by: Nysal Jan K.A. Tested-by: Samir M Reviewed-by: Sourabh Jain Signed-off-by: Madhavan Srinivasan Link: https://patch.msgid.link/20251028105516.26258-1-nysal@linux.ibm.com

kexec: Include kernel-end even without crashkernel

2025-11-11T09:04:15Z

Certain versions of kexec don't even work without kernel-end being added to the device-tree. Add it even if crash-kernel is disabled. Signed-off-by: Ben Collins Reviewed-by: Sourabh Jain Signed-off-by: Madhavan Srinivasan Link: https://patch.msgid.link/2025042122-inescapable-mandrill-8a5ff2@boujee-and-buff

powerpc/kdump: Fix size calculation for hot-removed memory ranges

2025-11-11T08:41:55Z

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 Type Offset VirtAddr PhysAddr FileSiz MemSiz Flags Align LOAD 0x0000000b013d0000 0xc000000b80000000 0x0000000b80000000 0xffffffffc0000000 0xffffffffc0000000 RWE 0x0 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 Signed-off-by: Sourabh Jain Signed-off-by: Madhavan Srinivasan Link: https://patch.msgid.link/20251105033941.1752287-1-sourabhjain@linux.ibm.com

powerpc/kdump: Add support for crashkernel CMA reservation

2025-11-11T08:41:08Z

Commit 35c18f2933c5 ("Add a new optional ",cma" suffix to the crashkernel= command line option") and commit ab475510e042 ("kdump: implement reserve_crashkernel_cma") added CMA support for kdump crashkernel reservation. Extend crashkernel CMA reservation support to powerpc. The following changes are made to enable CMA reservation on powerpc: - Parse and obtain the CMA reservation size along with other crashkernel parameters - Call reserve_crashkernel_cma() to allocate the CMA region for kdump - Include the CMA-reserved ranges in the usable memory ranges for the kdump kernel to use. - Exclude the CMA-reserved ranges from the crash kernel memory to prevent them from being exported through /proc/vmcore. With the introduction of the CMA crashkernel regions, crash_exclude_mem_range() needs to be called multiple times to exclude both crashk_res and crashk_cma_ranges from the crash memory ranges. To avoid repetitive logic for validating mem_ranges size and handling reallocation when required, this functionality is moved to a new wrapper function crash_exclude_mem_range_guarded(). To ensure proper CMA reservation, reserve_crashkernel_cma() is called after pageblock_order is initialized. Update kernel-parameters.txt to document CMA support for crashkernel on powerpc architecture. Signed-off-by: Sourabh Jain Reviewed-by: Ritesh Harjani (IBM) Signed-off-by: Madhavan Srinivasan Link: https://patch.msgid.link/20251107080334.708028-1-sourabhjain@linux.ibm.com

Add a new optional ",cma" suffix to the crashkernel= command line option

2025-07-20T02:08:22Z

Patch series "kdump: crashkernel reservation from CMA", v5. This series implements a way to reserve additional crash kernel memory using CMA. Currently, all the memory for the crash kernel is not usable by the 1st (production) kernel. It is also unmapped so that it can't be corrupted by the fault that will eventually trigger the crash. This makes sense for the memory actually used by the kexec-loaded crash kernel image and initrd and the data prepared during the load (vmcoreinfo, ...). However, the reserved space needs to be much larger than that to provide enough run-time memory for the crash kernel and the kdump userspace. Estimating the amount of memory to reserve is difficult. Being too careful makes kdump likely to end in OOM, being too generous takes even more memory from the production system. Also, the reservation only allows reserving a single contiguous block (or two with the "low" suffix). I've seen systems where this fails because the physical memory is fragmented. By reserving additional crashkernel memory from CMA, the main crashkernel reservation can be just large enough to fit the kernel and initrd image, minimizing the memory taken away from the production system. Most of the run-time memory for the crash kernel will be memory previously available to userspace in the production system. As this memory is no longer wasted, the reservation can be done with a generous margin, making kdump more reliable. Kernel memory that we need to preserve for dumping is normally not allocated from CMA, unless it is explicitly allocated as movable. Currently this is only the case for memory ballooning and zswap. Such movable memory will be missing from the vmcore. User data is typically not dumped by makedumpfile. When dumping of user data is intended this new CMA reservation cannot be used. There are five patches in this series: The first adds a new ",cma" suffix to the recenly introduced generic crashkernel parsing code. parse_crashkernel() takes one more argument to store the cma reservation size. The second patch implements reserve_crashkernel_cma() which performs the reservation. If the requested size is not available in a single range, multiple smaller ranges will be reserved. The third patch updates Documentation/, explicitly mentioning the potential DMA corruption of the CMA-reserved memory. The fourth patch adds a short delay before booting the kdump kernel, allowing pending DMA transfers to finish. The fifth patch enables the functionality for x86 as a proof of concept. There are just three things every arch needs to do: - call reserve_crashkernel_cma() - include the CMA-reserved ranges in the physical memory map - exclude the CMA-reserved ranges from the memory available through /proc/vmcore by excluding them from the vmcoreinfo PT_LOAD ranges. Adding other architectures is easy and I can do that as soon as this series is merged. With this series applied, specifying crashkernel=100M craskhernel=1G,cma on the command line will make a standard crashkernel reservation of 100M, where kexec will load the kernel and initrd. An additional 1G will be reserved from CMA, still usable by the production system. The crash kernel will have 1.1G memory available. The 100M can be reliably predicted based on the size of the kernel and initrd. The new cma suffix is completely optional. When no crashkernel=size,cma is specified, everything works as before. This patch (of 5): Add a new cma_size parameter to parse_crashkernel(). When not NULL, call __parse_crashkernel to parse the CMA reservation size from "crashkernel=size,cma" and store it in cma_size. Set cma_size to NULL in all calls to parse_crashkernel(). Link: https://lkml.kernel.org/r/aEqnxxfLZMllMC8I@dwarf.suse.cz Link: https://lkml.kernel.org/r/aEqoQckgoTQNULnh@dwarf.suse.cz Signed-off-by: Jiri Bohac Cc: Baoquan He Cc: Dave Young Cc: Donald Dutile Cc: Michal Hocko Cc: Philipp Rudo Cc: Pingfan Liu Cc: Tao Liu Cc: Vivek Goyal Cc: David Hildenbrand Signed-off-by: Andrew Morton

powerpc/crash: Fix non-smp kexec preparation

2025-04-29T06:10:46Z

In non-smp configurations, crash_kexec_prepare is never called in the crash shutdown path. One result of this is that the crashing_cpu variable is never set, preventing crash_save_cpu from storing the NT_PRSTATUS elf note in the core dump. Fixes: c7255058b543 ("powerpc/crash: save cpu register data in crash_smp_send_stop()") Signed-off-by: Eddie James Reviewed-by: Hari Bathini Signed-off-by: Madhavan Srinivasan Link: https://patch.msgid.link/20250211162054.857762-1-eajames@linux.ibm.com

Merge tag 'mm-nonmm-stable-2025-03-30-18-23' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2025-04-01T17:06:52Z

Pull non-MM updates from Andrew Morton: - The series "powerpc/crash: use generic crashkernel reservation" from Sourabh Jain changes powerpc's kexec code to use more of the generic layers. - The series "get_maintainer: report subsystem status separately" from Vlastimil Babka makes some long-requested improvements to the get_maintainer output. - The series "ucount: Simplify refcounting with rcuref_t" from Sebastian Siewior cleans up and optimizing the refcounting in the ucount code. - The series "reboot: support runtime configuration of emergency hw_protection action" from Ahmad Fatoum improves the ability for a driver to perform an emergency system shutdown or reboot. - The series "Converge on using secs_to_jiffies() part two" from Easwar Hariharan performs further migrations from msecs_to_jiffies() to secs_to_jiffies(). - The series "lib/interval_tree: add some test cases and cleanup" from Wei Yang permits more userspace testing of kernel library code, adds some more tests and performs some cleanups. - The series "hung_task: Dump the blocking task stacktrace" from Masami Hiramatsu arranges for the hung_task detector to dump the stack of the blocking task and not just that of the blocked task. - The series "resource: Split and use DEFINE_RES*() macros" from Andy Shevchenko provides some cleanups to the resource definition macros. - Plus the usual shower of singleton patches - please see the individual changelogs for details. * tag 'mm-nonmm-stable-2025-03-30-18-23' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (77 commits) mailmap: consolidate email addresses of Alexander Sverdlin fs/procfs: fix the comment above proc_pid_wchan() relay: use kasprintf() instead of fixed buffer formatting resource: replace open coded variant of DEFINE_RES() resource: replace open coded variants of DEFINE_RES_*_NAMED() resource: replace open coded variant of DEFINE_RES_NAMED_DESC() resource: split DEFINE_RES_NAMED_DESC() out of DEFINE_RES_NAMED() samples: add hung_task detector mutex blocking sample hung_task: show the blocker task if the task is hung on mutex kexec_core: accept unaccepted kexec segments' destination addresses watchdog/perf: optimize bytes copied and remove manual NUL-termination lib/interval_tree: fix the comment of interval_tree_span_iter_next_gap() lib/interval_tree: skip the check before go to the right subtree lib/interval_tree: add test case for span iteration lib/interval_tree: add test case for interval_tree_iter_xxx() helpers lib/rbtree: add random seed lib/rbtree: split tests lib/rbtree: enable userland test suite for rbtree related data structure checkpatch: describe --min-conf-desc-length scripts/gdb/symbols: determine KASLR offset on s390 ...

powerpc/crash: use generic crashkernel reservation

2025-03-17T05:30:48Z

Commit 0ab97169aa05 ("crash_core: add generic function to do reservation") added a generic function to reserve crashkernel memory. So let's use the same function on powerpc and remove the architecture-specific code that essentially does the same thing. The generic crashkernel reservation also provides a way to split the crashkernel reservation into high and low memory reservations, which can be enabled for powerpc in the future. Along with moving to the generic crashkernel reservation, the code related to finding the base address for the crashkernel has been separated into its own function name get_crash_base() for better readability and maintainability. Link: https://lkml.kernel.org/r/20250131113830.925179-8-sourabhjain@linux.ibm.com Signed-off-by: Sourabh Jain Reviewed-by: Mahesh Salgaonkar Acked-by: Hari Bathini Cc: Baoquan he Cc: Madhavan Srinivasan Cc: Michael Ellerman Signed-off-by: Andrew Morton