From 6a2561f92e7d74536b6eba3ffdcf66d60d44031c Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Thu, 8 Jun 2023 12:18:35 -0700 Subject: [PATCH] parisc: add pte_unmap() to balance get_ptep() To keep balance in future, remember to pte_unmap() after a successful get_ptep(). And act as if flush_cache_pages() really needs a map there, to read the pfn before "unmapping", to be sure page table is not removed. Link: https://lkml.kernel.org/r/653369-95ef-acd2-d6ea-e95f5a997493@google.com Signed-off-by: Hugh Dickins Cc: Alexander Gordeev Cc: Alexandre Ghiti Cc: Aneesh Kumar K.V Cc: Catalin Marinas Cc: Christian Borntraeger Cc: Chris Zankel Cc: Claudio Imbrenda Cc: David Hildenbrand Cc: "David S. Miller" Cc: Geert Uytterhoeven Cc: Greg Ungerer Cc: Heiko Carstens Cc: Helge Deller Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: John David Anglin Cc: John Paul Adrian Glaubitz Cc: Kirill A. Shutemov Cc: Matthew Wilcox (Oracle) Cc: Max Filippov Cc: Michael Ellerman Cc: Michal Simek Cc: Mike Kravetz Cc: Mike Rapoport (IBM) Cc: Palmer Dabbelt Cc: Peter Zijlstra Cc: Qi Zheng Cc: Russell King Cc: Suren Baghdasaryan Cc: Thomas Bogendoerfer Cc: Thomas Gleixner Cc: Will Deacon Signed-off-by: Andrew Morton --- arch/parisc/kernel/cache.c | 26 +++++++++++++++++++++----- 1 file changed, 21 insertions(+), 5 deletions(-) diff --git a/arch/parisc/kernel/cache.c b/arch/parisc/kernel/cache.c index ca4a302d..5011602 100644 --- a/arch/parisc/kernel/cache.c +++ b/arch/parisc/kernel/cache.c @@ -426,10 +426,15 @@ void flush_dcache_page(struct page *page) offset = (pgoff - mpnt->vm_pgoff) << PAGE_SHIFT; addr = mpnt->vm_start + offset; if (parisc_requires_coherency()) { + bool needs_flush = false; pte_t *ptep; ptep = get_ptep(mpnt->vm_mm, addr); - if (ptep && pte_needs_flush(*ptep)) + if (ptep) { + needs_flush = pte_needs_flush(*ptep); + pte_unmap(ptep); + } + if (needs_flush) flush_user_cache_page(mpnt, addr); } else { /* @@ -561,14 +566,20 @@ EXPORT_SYMBOL(flush_kernel_dcache_page_addr); static void flush_cache_page_if_present(struct vm_area_struct *vma, unsigned long vmaddr, unsigned long pfn) { - pte_t *ptep = get_ptep(vma->vm_mm, vmaddr); + bool needs_flush = false; + pte_t *ptep; /* * The pte check is racy and sometimes the flush will trigger * a non-access TLB miss. Hopefully, the page has already been * flushed. */ - if (ptep && pte_needs_flush(*ptep)) + ptep = get_ptep(vma->vm_mm, vmaddr); + if (ptep) { + needs_flush = pte_needs_flush(*ptep); + pte_unmap(ptep); + } + if (needs_flush) flush_cache_page(vma, vmaddr, pfn); } @@ -635,17 +646,22 @@ static void flush_cache_pages(struct vm_area_struct *vma, unsigned long start, u pte_t *ptep; for (addr = start; addr < end; addr += PAGE_SIZE) { + bool needs_flush = false; /* * The vma can contain pages that aren't present. Although * the pte search is expensive, we need the pte to find the * page pfn and to check whether the page should be flushed. */ ptep = get_ptep(vma->vm_mm, addr); - if (ptep && pte_needs_flush(*ptep)) { + if (ptep) { + needs_flush = pte_needs_flush(*ptep); + pfn = pte_pfn(*ptep); + pte_unmap(ptep); + } + if (needs_flush) { if (parisc_requires_coherency()) { flush_user_cache_page(vma, addr); } else { - pfn = pte_pfn(*ptep); if (WARN_ON(!pfn_valid(pfn))) return; __flush_cache_page(vma, addr, PFN_PHYS(pfn)); -- 2.7.4