From: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx> Subject: vmalloc: choose a better start address in vm_area_register_early() Percpu embedded first chunk allocator is the firstly option, but it could fail on ARM64, eg, "percpu: max_distance=0x5fcfdc640000 too large for vmalloc space 0x781fefff0000" "percpu: max_distance=0x600000540000 too large for vmalloc space 0x7dffb7ff0000" "percpu: max_distance=0x5fff9adb0000 too large for vmalloc space 0x5dffb7ff0000" then we could meet "WARNING: CPU: 15 PID: 461 at vmalloc.c:3087 pcpu_get_vm_areas+0x488/0x838" and the system cannot boot successfully. Let's implement page mapping percpu first chunk allocator as a fallback to the embedding allocator to increase the robustness of the system. Also fix a crash when both NEED_PER_CPU_PAGE_FIRST_CHUNK and KASAN_VMALLOC enabled. Tested on ARM64 qemu with cmdline "percpu_alloc=page". This patch (of 3): There are some fixed locations in the vmalloc area be reserved in ARM(see iotable_init()) and ARM64(see map_kernel()), but for pcpu_page_first_chunk(), it calls vm_area_register_early() and choose VMALLOC_START as the start address of vmap area which could be conflicted with above address, then could trigger a BUG_ON in vm_area_add_early(). Let's choose a suit start address by traversing the vmlist. Link: https://lkml.kernel.org/r/20210910053354.26721-1-wangkefeng.wang@xxxxxxxxxx Link: https://lkml.kernel.org/r/20210910053354.26721-2-wangkefeng.wang@xxxxxxxxxx Signed-off-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx> Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx> Cc: Will Deacon <will@xxxxxxxxxx> Cc: Andrey Ryabinin <ryabinin.a.a@xxxxxxxxx> Cc: Andrey Konovalov <andreyknvl@xxxxxxxxx> Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx> Cc: Marco Elver <elver@xxxxxxxxxx> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/vmalloc.c | 18 ++++++++++++------ 1 file changed, 12 insertions(+), 6 deletions(-) --- a/mm/vmalloc.c~vmalloc-choose-a-better-start-address-in-vm_area_register_early +++ a/mm/vmalloc.c @@ -2276,15 +2276,21 @@ void __init vm_area_add_early(struct vm_ */ void __init vm_area_register_early(struct vm_struct *vm, size_t align) { - static size_t vm_init_off __initdata; - unsigned long addr; + unsigned long addr = ALIGN(VMALLOC_START, align); + struct vm_struct *cur, **p; - addr = ALIGN(VMALLOC_START + vm_init_off, align); - vm_init_off = PFN_ALIGN(addr + vm->size) - VMALLOC_START; + BUG_ON(vmap_initialized); - vm->addr = (void *)addr; + for (p = &vmlist; (cur = *p) != NULL; p = &cur->next) { + if ((unsigned long)cur->addr - addr >= vm->size) + break; + addr = ALIGN((unsigned long)cur->addr + cur->size, align); + } - vm_area_add_early(vm); + BUG_ON(addr > VMALLOC_END - vm->size); + vm->addr = (void *)addr; + vm->next = *p; + *p = vm; } static void vmap_init_free_space(void) _
