On Thu, 25. Jul 02:19, hailong.liu@xxxxxxxx wrote:
> From: "Hailong.Liu" <hailong.liu@xxxxxxxx>
>
> The scenario where the issue occurs is as follows:
> CONFIG: vmap_allow_huge = true && 2M is for PMD_SIZE
> kvmalloc(2M)
> __vmalloc_node_range(vm_flags=VM_ALLOW_HUGE_VMAP)
> vm_area_alloc_pages(order=9) --->allocs order9 failed and fallback to order0
> and phys_addr is aligned with PMD_SIZE
> vmap_pages_range
> vmap_pages_range_noflush
> __vmap_pages_range_noflush(page_shift = 21) ----> incorrect vmap *huge* here
>
> Fix it by introducing VM_AREA_ALLOC_PAGES_FALLBACK in page->private if fallback to 0.
> Fixes: e9c3cda4d86e ("mm, vmalloc: fix high order __GFP_NOFAIL allocations")
>
> CC: Barry Song <21cnbao@xxxxxxxxx>
> Reported-by: Tangquan.Zheng <zhengtangquan@xxxxxxxx>
> Signed-off-by: Hailong.Liu <hailong.liu@xxxxxxxx>
> ---
> mm/vmalloc.c | 14 ++++++++++++--
> 1 file changed, 12 insertions(+), 2 deletions(-)
>
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index 03c78fae06f3..b35dfd3eeee3 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -75,6 +75,8 @@ early_param("nohugevmalloc", set_nohugevmalloc);
> static const bool vmap_allow_huge = false;
> #endif /* CONFIG_HAVE_ARCH_HUGE_VMALLOC */
>
> +#define VM_AREA_ALLOC_PAGES_FALLBACK 0x1
> +
> bool is_vmalloc_addr(const void *x)
> {
> unsigned long addr = (unsigned long)kasan_reset_tag(x);
> @@ -604,8 +606,13 @@ int __vmap_pages_range_noflush(unsigned long addr, unsigned long end,
> WARN_ON(page_shift < PAGE_SHIFT);
>
> if (!IS_ENABLED(CONFIG_HAVE_ARCH_HUGE_VMALLOC) ||
> - page_shift == PAGE_SHIFT)
> - return vmap_small_pages_range_noflush(addr, end, prot, pages);
> + page_shift == PAGE_SHIFT ||
> + page_private(pages[0]) == VM_AREA_ALLOC_PAGES_FALLBACK) {
> + int ret = vmap_small_pages_range_noflush(addr, end, prot, pages);
> +
> + set_page_private(pages[0], 0);
> + return ret;
> + }
>
> for (i = 0; i < nr; i += 1U << (page_shift - PAGE_SHIFT)) {
> int err;
> @@ -3583,6 +3590,7 @@ vm_area_alloc_pages(gfp_t gfp, int nid,
>
> /* fall back to the zero order allocations */
> alloc_gfp |= __GFP_NOFAIL;
> + fallback = true;
Sry for my mistake, I forget define fallback here.
BTW, This is not the optimal solution. Does anyone have a better idea? Glad to
hear:)
> order = 0;
> continue;
> }
> @@ -3608,6 +3616,8 @@ vm_area_alloc_pages(gfp_t gfp, int nid,
> cond_resched();
> nr_allocated += 1U << order;
> }
> + if (nr_allocated && fallback)
> + set_page_private(pages[0], VM_AREA_ALLOC_PAGES_FALLBACK);
>
> return nr_allocated;
> }
> --
> 2.34.1
>
--
help you, help me,
Hailong.
