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[73.93.239.127]) by smtp.gmail.com with ESMTPSA id c26sm10442321pfo.97.2021.03.30.13.39.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 30 Mar 2021 13:39:02 -0700 (PDT) From: Yang Shi To: jhubbard@nvidia.com, akpm@linux-foundation.org Cc: shy828301@gmail.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [v2 PATCH] mm: gup: remove FOLL_SPLIT Date: Tue, 30 Mar 2021 13:38:59 -0700 Message-Id: <20210330203900.9222-1-shy828301@gmail.com> X-Mailer: git-send-email 2.26.2 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Since commit 5a52c9df62b4 ("uprobe: use FOLL_SPLIT_PMD instead of FOLL_SPLIT") and commit ba925fa35057 ("s390/gmap: improve THP splitting") FOLL_SPLIT has not been used anymore. Remove the dead code. Reviewed-by: John Hubbard Signed-off-by: Yang Shi --- v2: Remove the reference in documentation. Documentation/vm/transhuge.rst | 5 ----- include/linux/mm.h | 1 - mm/gup.c | 28 ++-------------------------- 3 files changed, 2 insertions(+), 32 deletions(-) diff --git a/Documentation/vm/transhuge.rst b/Documentation/vm/transhuge.rst index 0ed23e59abe5..216db1d67d04 100644 --- a/Documentation/vm/transhuge.rst +++ b/Documentation/vm/transhuge.rst @@ -53,11 +53,6 @@ prevent the page from being split by anyone. of handling GUP on hugetlbfs will also work fine on transparent hugepage backed mappings. -In case you can't handle compound pages if they're returned by -follow_page, the FOLL_SPLIT bit can be specified as a parameter to -follow_page, so that it will split the hugepages before returning -them. - Graceful fallback ================= diff --git a/include/linux/mm.h b/include/linux/mm.h index 8ba434287387..3568836841f9 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2780,7 +2780,6 @@ struct page *follow_page(struct vm_area_struct *vma, unsigned long address, #define FOLL_NOWAIT 0x20 /* if a disk transfer is needed, start the IO * and return without waiting upon it */ #define FOLL_POPULATE 0x40 /* fault in page */ -#define FOLL_SPLIT 0x80 /* don't return transhuge pages, split them */ #define FOLL_HWPOISON 0x100 /* check page is hwpoisoned */ #define FOLL_NUMA 0x200 /* force NUMA hinting page fault */ #define FOLL_MIGRATION 0x400 /* wait for page to replace migration entry */ diff --git a/mm/gup.c b/mm/gup.c index e40579624f10..f3d45a8f18ae 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -435,18 +435,6 @@ static struct page *follow_page_pte(struct vm_area_struct *vma, } } - if (flags & FOLL_SPLIT && PageTransCompound(page)) { - get_page(page); - pte_unmap_unlock(ptep, ptl); - lock_page(page); - ret = split_huge_page(page); - unlock_page(page); - put_page(page); - if (ret) - return ERR_PTR(ret); - goto retry; - } - /* try_grab_page() does nothing unless FOLL_GET or FOLL_PIN is set. */ if (unlikely(!try_grab_page(page, flags))) { page = ERR_PTR(-ENOMEM); @@ -591,7 +579,7 @@ static struct page *follow_pmd_mask(struct vm_area_struct *vma, spin_unlock(ptl); return follow_page_pte(vma, address, pmd, flags, &ctx->pgmap); } - if (flags & (FOLL_SPLIT | FOLL_SPLIT_PMD)) { + if (flags & FOLL_SPLIT_PMD) { int ret; page = pmd_page(*pmd); if (is_huge_zero_page(page)) { @@ -600,19 +588,7 @@ static struct page *follow_pmd_mask(struct vm_area_struct *vma, split_huge_pmd(vma, pmd, address); if (pmd_trans_unstable(pmd)) ret = -EBUSY; - } else if (flags & FOLL_SPLIT) { - if (unlikely(!try_get_page(page))) { - spin_unlock(ptl); - return ERR_PTR(-ENOMEM); - } - spin_unlock(ptl); - lock_page(page); - ret = split_huge_page(page); - unlock_page(page); - put_page(page); - if (pmd_none(*pmd)) - return no_page_table(vma, flags); - } else { /* flags & FOLL_SPLIT_PMD */ + } else { spin_unlock(ptl); split_huge_pmd(vma, pmd, address); ret = pte_alloc(mm, pmd) ? -ENOMEM : 0; -- 2.26.2