linux-kernel - [PATCH] mm: Resolve some multi-size THP review nits

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Date:   Thu, 14 Dec 2023 16:02:51 +0000
From:   Ryan Roberts <ryan.roberts@....com>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        Matthew Wilcox <willy@...radead.org>,
        Yin Fengwei <fengwei.yin@...el.com>,
        David Hildenbrand <david@...hat.com>,
        Yu Zhao <yuzhao@...gle.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Anshuman Khandual <anshuman.khandual@....com>,
        Yang Shi <shy828301@...il.com>,
        "Huang, Ying" <ying.huang@...el.com>, Zi Yan <ziy@...dia.com>,
        Luis Chamberlain <mcgrof@...nel.org>,
        Itaru Kitayama <itaru.kitayama@...il.com>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        John Hubbard <jhubbard@...dia.com>,
        David Rientjes <rientjes@...gle.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Hugh Dickins <hughd@...gle.com>,
        Kefeng Wang <wangkefeng.wang@...wei.com>,
        Barry Song <21cnbao@...il.com>,
        Alistair Popple <apopple@...dia.com>,
        Dan Carpenter <dan.carpenter@...aro.org>
Cc:     Ryan Roberts <ryan.roberts@....com>, linux-mm@...ck.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH] mm: Resolve some multi-size THP review nits

Tidy code based on review feedback for final version of multi-size THP:

 - Comment added to explain alloc_anon_folio() error protocol
 - ifdefery simplified for alloc_anon_folio()

Signed-off-by: Ryan Roberts <ryan.roberts@....com>
---
Hi Andrew,

Hopefully this is the final tweak. Could you please squash this with the
"mm: thp: Support allocation of anonymous multi-size THP" patch in mm-unstable?

Or if you prefer me to re-post the entire series, just let me know.

Thanks,
Ryan


 mm/memory.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/mm/memory.c b/mm/memory.c
index 8f0b936b90b5..3c530b639559 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4137,9 +4137,9 @@ static bool pte_range_none(pte_t *pte, int nr_pages)
 	return true;
 }

-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
 static struct folio *alloc_anon_folio(struct vm_fault *vmf)
 {
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
 	struct vm_area_struct *vma = vmf->vma;
 	unsigned long orders;
 	struct folio *folio;
@@ -4199,12 +4199,9 @@ static struct folio *alloc_anon_folio(struct vm_fault *vmf)
 	}

 fallback:
-	return vma_alloc_zeroed_movable_folio(vma, vmf->address);
-}
-#else
-#define alloc_anon_folio(vmf) \
-		vma_alloc_zeroed_movable_folio((vmf)->vma, (vmf)->address)
 #endif
+	return vma_alloc_zeroed_movable_folio(vmf->vma, vmf->address);
+}

 /*
  * We enter with non-exclusive mmap_lock (to exclude vma changes,
@@ -4260,6 +4257,7 @@ static vm_fault_t do_anonymous_page(struct vm_fault *vmf)
 	/* Allocate our own private page. */
 	if (unlikely(anon_vma_prepare(vma)))
 		goto oom;
+	/* Returns NULL on OOM or ERR_PTR(-EAGAIN) if we must retry the fault */
 	folio = alloc_anon_folio(vmf);
 	if (IS_ERR(folio))
 		return 0;
--
2.25.1