Per-CPU allocations are not guaranteed to be physically contiguous. However, kdump kernel and user-space code assumes that per-CPU memory, used for saving CPU registers on crash, is. This can cause corrupted /proc/vmcore in some cases - the main symptom being huge ELF note section.
Force page alignment for note_buf_t to ensure that this assumption holds. Signed-off-by: Eugene Surovegin <[email protected]> CC: Eric Biederman <[email protected]> CC: Vivek Goyal <[email protected]> CC: kexec-list <[email protected]> --- kernel/kexec.c | 9 +++++++-- 1 files changed, 7 insertions(+), 2 deletions(-) diff --git a/kernel/kexec.c b/kernel/kexec.c index 7b08867..e641b5c 100644 --- a/kernel/kexec.c +++ b/kernel/kexec.c @@ -1232,8 +1232,13 @@ void crash_save_cpu(struct pt_regs *regs, int cpu) static int __init crash_notes_memory_init(void) { - /* Allocate memory for saving cpu registers. */ - crash_notes = alloc_percpu(note_buf_t); + /* Allocate memory for saving cpu registers. + * Force page alignment to avoid crossing physical page boundary - + * kexec-tools and kernel /proc/vmcore handler assume these per-CPU + * chunks are physically contiguous. + */ + crash_notes = (note_buf_t __percpu *)__alloc_percpu(sizeof(note_buf_t), + PAGE_SIZE); if (!crash_notes) { printk("Kexec: Memory allocation for saving cpu register" " states failed\n"); -- 1.7.9.1 _______________________________________________ kexec mailing list [email protected] http://lists.infradead.org/mailman/listinfo/kexec
