Commit 07e6d409 authored by ZhangPeng's avatar ZhangPeng Committed by Andrew Morton
Browse files

userfaultfd: convert mfill_atomic_pte_copy() to use a folio 

Patch series "userfaultfd: convert userfaultfd functions to use folios",
v6.

This patch series converts several userfaultfd functions to use folios.


This patch (of 6):

Call vma_alloc_folio() directly instead of alloc_page_vma() and convert
page_kaddr to kaddr in mfill_atomic_pte_copy().  Removes several calls to
compound_head().

Link: https://lkml.kernel.org/r/20230410133932.32288-1-zhangpeng362@huawei.com
Link: https://lkml.kernel.org/r/20230410133932.32288-2-zhangpeng362@huawei.com


Signed-off-by: default avatarZhangPeng <zhangpeng362@huawei.com>
Reviewed-by: default avatarSidhartha Kumar <sidhartha.kumar@oracle.com>
Reviewed-by: default avatarMike Kravetz <mike.kravetz@oracle.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nanyong Sun <sunnanyong@huawei.com>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent b4aca547

mm/userfaultfd.c

+16 −16
Original line number Diff line number Diff line
@@ -135,17 +135,18 @@ static int mfill_atomic_pte_copy(pmd_t *dst_pmd, 
				 uffd_flags_t flags,

				 struct page **pagep)

{

	void *page_kaddr;

	void *kaddr;

	int ret;

	struct page *page;

	struct folio *folio;



	if (!*pagep) {

		ret = -ENOMEM;

		page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, dst_vma, dst_addr);

		if (!page)

		folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0, dst_vma,

					dst_addr, false);

		if (!folio)

			goto out;



		page_kaddr = kmap_local_page(page);

		kaddr = kmap_local_folio(folio, 0);

		/*

		 * The read mmap_lock is held here.  Despite the

		 * mmap_lock being read recursive a deadlock is still
@@ -162,45 +163,44 @@ static int mfill_atomic_pte_copy(pmd_t *dst_pmd, 
		 * and retry the copy outside the mmap_lock.

		 */

		pagefault_disable();

		ret = copy_from_user(page_kaddr,

				     (const void __user *) src_addr,

		ret = copy_from_user(kaddr, (const void __user *) src_addr,

				     PAGE_SIZE);

		pagefault_enable();

		kunmap_local(page_kaddr);

		kunmap_local(kaddr);



		/* fallback to copy_from_user outside mmap_lock */

		if (unlikely(ret)) {

			ret = -ENOENT;

			*pagep = page;

			*pagep = &folio->page;

			/* don't free the page */

			goto out;

		}



		flush_dcache_page(page);

		flush_dcache_folio(folio);

	} else {

		page = *pagep;

		folio = page_folio(*pagep);

		*pagep = NULL;

	}



	/*

	 * The memory barrier inside __SetPageUptodate makes sure that

	 * The memory barrier inside __folio_mark_uptodate makes sure that

	 * preceding stores to the page contents become visible before

	 * the set_pte_at() write.

	 */

	__SetPageUptodate(page);

	__folio_mark_uptodate(folio);



	ret = -ENOMEM;

	if (mem_cgroup_charge(page_folio(page), dst_vma->vm_mm, GFP_KERNEL))

	if (mem_cgroup_charge(folio, dst_vma->vm_mm, GFP_KERNEL))

		goto out_release;



	ret = mfill_atomic_install_pte(dst_pmd, dst_vma, dst_addr,

				       page, true, flags);

				       &folio->page, true, flags);

	if (ret)

		goto out_release;

out:

	return ret;

out_release:

	put_page(page);

	folio_put(folio);

	goto out;

}