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From:   Ryan Roberts <ryan.roberts@arm.com>
To:     Andrew Morton <akpm@linux-foundation.org>,
        Matthew Wilcox <willy@infradead.org>,
        Yin Fengwei <fengwei.yin@intel.com>,
        David Hildenbrand <david@redhat.com>,
        Yu Zhao <yuzhao@google.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Anshuman Khandual <anshuman.khandual@arm.com>,
        Yang Shi <shy828301@gmail.com>,
        "Huang, Ying" <ying.huang@intel.com>, Zi Yan <ziy@nvidia.com>,
        Luis Chamberlain <mcgrof@kernel.org>,
        Itaru Kitayama <itaru.kitayama@gmail.com>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        John Hubbard <jhubbard@nvidia.com>,
        David Rientjes <rientjes@google.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        Hugh Dickins <hughd@google.com>,
        Kefeng Wang <wangkefeng.wang@huawei.com>,
        Barry Song <21cnbao@gmail.com>,
        Alistair Popple <apopple@nvidia.com>,
        Dan Carpenter <dan.carpenter@linaro.org>
Cc:     Ryan Roberts <ryan.roberts@arm.com>, linux-mm@kvack.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: [PATCH] mm: Resolve some multi-size THP review nits
Date:   Thu, 14 Dec 2023 16:02:51 +0000
Message-Id: <20231214160251.3574571-1-ryan.roberts@arm.com>
In-Reply-To: <e2da3c78-85f7-4516-bbab-97fac9629dcc@suswa.mountain>
References: <e2da3c78-85f7-4516-bbab-97fac9629dcc@suswa.mountain>
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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@arm.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