Re: [RESEND PATCH v1] mm/vmalloc: fix page mapping if vm_area_alloc_pages() with high order fallback to order 0

On Fri 23-08-24 18:42:47, Uladzislau Rezki wrote: [...]

@@ -3666,7 +3655,16 @@ static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask, set_vm_area_page_order(area, page_shift - PAGE_SHIFT); page_order = vm_area_page_order(area);

• area->nr_pages = vm_area_alloc_pages(gfp_mask | __GFP_NOWARN,

• /*

• * Higher order nofail allocations are really expensive and
  

• * potentially dangerous (pre-mature OOM, disruptive reclaim
  

• * and compaction etc.
  

• *
  

• * Please note, the __vmalloc_node_range_noprof() falls-back
  

• * to order-0 pages if high-order attempt has been unsuccessful.
  

• */
  

• area->nr_pages = vm_area_alloc_pages(page_order ?

• gfp_mask &= ~__GFP_NOFAIL : gfp_mask | __GFP_NOWARN,
  

  node, page_order, nr_small_pages, area->pages);

atomic_long_add(area->nr_pages, &nr_vmalloc_pages);

<snip>

Is that aligned with your wish?

I am not a great fan of modifying gfp_mask inside the ternary operator like that. It makes the code harder to read. Is there any actual reason to simply drop GFP_NOFAIL unconditionally and rely do the NOFAIL handling for all orders at the same place?

Not that I care about this much TBH. It is an improvement to drop all the NOFAIL specifics from vm_area_alloc_pages.