The patch titled
Subject: mm-hugetlb_vmemmap-remap-head-page-to-newly-allocated-page-v3
has been added to the -mm mm-unstable branch. Its filename is
mm-hugetlb_vmemmap-remap-head-page-to-newly-allocated-page-v3.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-hugetlb_vmemmap-remap-head-page-to-newly-allocated-page-v3.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Joao Martins <joao.m.martins@xxxxxxxxxx>
Subject: mm-hugetlb_vmemmap-remap-head-page-to-newly-allocated-page-v3
Date: Wed, 9 Nov 2022 20:06:23 +0000
Comments from Muchun:
* Delete the comment above the tlb flush
* Move the head vmemmap page copy into vmemmap_remap_free()
* Add and del the new head page to the vmemmap_pages (to be freed
in case of error)
* Move the remap of the head like the tail pages in vmemmap_remap_pte()
but special casing only when addr == reuse_Addr
* Removes the PAGE_SIZE alignment check as the code has the assumption
that start/end are page-aligned (and VM_BUG_ON otherwise).
* Adjusted commit message taking the above changes into account.
Link: https://lkml.kernel.org/r/20221109200623.96867-1-joao.m.martins@xxxxxxxxxx
Signed-off-by: Joao Martins <joao.m.martins@xxxxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/hugetlb_vmemmap.c | 55 +++++++++++------------------------------
1 file changed, 15 insertions(+), 40 deletions(-)
--- a/mm/hugetlb_vmemmap.c~mm-hugetlb_vmemmap-remap-head-page-to-newly-allocated-page-v3
+++ a/mm/hugetlb_vmemmap.c
@@ -22,7 +22,6 @@
*
* @remap_pte: called for each lowest-level entry (PTE).
* @nr_walked: the number of walked pte.
- * @head_page: the page which replaces the head vmemmap page.
* @reuse_page: the page which is reused for the tail vmemmap pages.
* @reuse_addr: the virtual address of the @reuse_page page.
* @vmemmap_pages: the list head of the vmemmap pages that can be freed
@@ -32,7 +31,6 @@ struct vmemmap_remap_walk {
void (*remap_pte)(pte_t *pte, unsigned long addr,
struct vmemmap_remap_walk *walk);
unsigned long nr_walked;
- struct page *head_page;
struct page *reuse_page;
unsigned long reuse_addr;
struct list_head *vmemmap_pages;
@@ -107,26 +105,10 @@ static void vmemmap_pte_range(pmd_t *pmd
* remapping (which is calling @walk->remap_pte).
*/
if (!walk->reuse_page) {
- struct page *page = pte_page(*pte);
-
- /*
- * Copy the data from the original head, and remap to
- * the newly allocated page.
- */
- if (walk->head_page) {
- memcpy(page_address(walk->head_page),
- page_address(page), PAGE_SIZE);
- walk->remap_pte(pte, addr, walk);
- page = walk->head_page;
- }
-
- walk->reuse_page = page;
-
+ walk->reuse_page = pte_page(*pte);
/*
- * Because the reuse address is part of the range that
- * we are walking or the head page was remapped to a
- * new page, skip the reuse address range.
- * .
+ * Because the reuse address is part of the range that we are
+ * walking, skip the reuse address range.
*/
addr += PAGE_SIZE;
pte++;
@@ -221,11 +203,6 @@ static int vmemmap_remap_range(unsigned
return ret;
} while (pgd++, addr = next, addr != end);
- /*
- * We change the mapping of the vmemmap virtual address range
- * [@start, end], so we only need to flush the TLB which
- * belongs to the range.
- */
flush_tlb_kernel_range(start, end);
return 0;
@@ -262,21 +239,16 @@ static void vmemmap_remap_pte(pte_t *pte
* to the tail pages.
*/
pgprot_t pgprot = PAGE_KERNEL_RO;
- struct page *reuse = walk->reuse_page;
struct page *page = pte_page(*pte);
pte_t entry;
- /*
- * When there's no walk::reuse_page, it means we allocated a new head
- * page (stored in walk::head_page) and copied from the old head page.
- * In that case use the walk::head_page as the page to remap.
- */
- if (!reuse) {
+ /* Remapping the head page requires r/w */
+ if (unlikely(addr == walk->reuse_addr)) {
pgprot = PAGE_KERNEL;
- reuse = walk->head_page;
+ list_del(&walk->reuse_page->lru);
}
- entry = mk_pte(reuse, pgprot);
+ entry = mk_pte(walk->reuse_page, pgprot);
list_add_tail(&page->lru, walk->vmemmap_pages);
set_pte_at(&init_mm, addr, pte, entry);
}
@@ -345,9 +317,9 @@ static int vmemmap_remap_free(unsigned l
.reuse_addr = reuse,
.vmemmap_pages = &vmemmap_pages,
};
- gfp_t gfp_mask = GFP_KERNEL|__GFP_RETRY_MAYFAIL|__GFP_NOWARN;
int nid = page_to_nid((struct page *)start);
- struct page *page = NULL;
+ gfp_t gfp_mask = GFP_KERNEL | __GFP_THISNODE | __GFP_NORETRY |
+ __GFP_NOWARN;
/*
* Allocate a new head vmemmap page to avoid breaking a contiguous
@@ -357,9 +329,12 @@ static int vmemmap_remap_free(unsigned l
* more allocations of hugepages. Fallback to the currently
* mapped head page in case should it fail to allocate.
*/
- if (IS_ALIGNED((unsigned long)start, PAGE_SIZE))
- page = alloc_pages_node(nid, gfp_mask, 0);
- walk.head_page = page;
+ walk.reuse_page = alloc_pages_node(nid, gfp_mask, 0);
+ if (walk.reuse_page) {
+ copy_page(page_to_virt(walk.reuse_page),
+ (void *)walk.reuse_addr);
+ list_add(&walk.reuse_page->lru, &vmemmap_pages);
+ }
/*
* In order to make remapping routine most efficient for the huge pages,
_
Patches currently in -mm which might be from joao.m.martins@xxxxxxxxxx are
mm-hugetlb_vmemmap-remap-head-page-to-newly-allocated-page.patch
mm-hugetlb_vmemmap-remap-head-page-to-newly-allocated-page-v3.patch
