The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 1a42010cdc26bb7e5912984f3c91b8c6d55f089a Mon Sep 17 00:00:00 2001
From: Martin Schwidefsky schwidefsky@de.ibm.com Date: Tue, 23 Apr 2019 10:53:21 +0200 Subject: [PATCH] s390/mm: convert to the generic get_user_pages_fast code
Define the gup_fast_permitted to check against the asce_limit of the mm attached to the current task, then replace the s390 specific gup code with the generic implementation in mm/gup.c.
Signed-off-by: Martin Schwidefsky schwidefsky@de.ibm.com
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig index 566f0b460d21..1c3fcf19c3af 100644 --- a/arch/s390/Kconfig +++ b/arch/s390/Kconfig @@ -149,6 +149,7 @@ config S390 select HAVE_FUNCTION_TRACER select HAVE_FUTEX_CMPXCHG if FUTEX select HAVE_GCC_PLUGINS + select HAVE_GENERIC_GUP select HAVE_KERNEL_BZIP2 select HAVE_KERNEL_GZIP select HAVE_KERNEL_LZ4 diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h index d48be9c27df9..394bec31cb97 100644 --- a/arch/s390/include/asm/pgtable.h +++ b/arch/s390/include/asm/pgtable.h @@ -1265,6 +1265,18 @@ static inline pte_t *pte_offset(pmd_t *pmd, unsigned long address) #define pte_offset_map(pmd, address) pte_offset_kernel(pmd, address) #define pte_unmap(pte) do { } while (0)
+static inline bool gup_fast_permitted(unsigned long start, int nr_pages) +{ + unsigned long len, end; + + len = (unsigned long) nr_pages << PAGE_SHIFT; + end = start + len; + if (end < start) + return false; + return end <= current->mm->context.asce_limit; +} +#define gup_fast_permitted gup_fast_permitted + #define pfn_pte(pfn,pgprot) mk_pte_phys(__pa((pfn) << PAGE_SHIFT),(pgprot)) #define pte_pfn(x) (pte_val(x) >> PAGE_SHIFT) #define pte_page(x) pfn_to_page(pte_pfn(x)) diff --git a/arch/s390/mm/Makefile b/arch/s390/mm/Makefile index f5880bfd1b0c..3175413186b9 100644 --- a/arch/s390/mm/Makefile +++ b/arch/s390/mm/Makefile @@ -4,7 +4,7 @@ #
obj-y := init.o fault.o extmem.o mmap.o vmem.o maccess.o -obj-y += page-states.o gup.o pageattr.o pgtable.o pgalloc.o +obj-y += page-states.o pageattr.o pgtable.o pgalloc.o
obj-$(CONFIG_CMM) += cmm.o obj-$(CONFIG_HUGETLB_PAGE) += hugetlbpage.o diff --git a/arch/s390/mm/gup.c b/arch/s390/mm/gup.c deleted file mode 100644 index a5ffcb132191..000000000000 --- a/arch/s390/mm/gup.c +++ /dev/null @@ -1,291 +0,0 @@ -// SPDX-License-Identifier: GPL-2.0 -/* - * Lockless get_user_pages_fast for s390 - * - * Copyright IBM Corp. 2010 - * Author(s): Martin Schwidefsky schwidefsky@de.ibm.com - */ -#include <linux/sched.h> -#include <linux/mm.h> -#include <linux/hugetlb.h> -#include <linux/vmstat.h> -#include <linux/pagemap.h> -#include <linux/rwsem.h> -#include <asm/pgtable.h> - -/* - * The performance critical leaf functions are made noinline otherwise gcc - * inlines everything into a single function which results in too much - * register pressure. - */ -static inline int gup_pte_range(pmd_t pmd, unsigned long addr, - unsigned long end, int write, struct page **pages, int *nr) -{ - struct page *head, *page; - unsigned long mask; - pte_t *ptep, pte; - - mask = (write ? _PAGE_PROTECT : 0) | _PAGE_INVALID | _PAGE_SPECIAL; - - ptep = pte_offset_map(&pmd, addr); - do { - pte = *ptep; - barrier(); - /* Similar to the PMD case, NUMA hinting must take slow path */ - if (pte_protnone(pte)) - return 0; - if ((pte_val(pte) & mask) != 0) - return 0; - VM_BUG_ON(!pfn_valid(pte_pfn(pte))); - page = pte_page(pte); - head = compound_head(page); - if (!page_cache_get_speculative(head)) - return 0; - if (unlikely(pte_val(pte) != pte_val(*ptep))) { - put_page(head); - return 0; - } - VM_BUG_ON_PAGE(compound_head(page) != head, page); - pages[*nr] = page; - (*nr)++; - - } while (ptep++, addr += PAGE_SIZE, addr != end); - - return 1; -} - -static inline int gup_huge_pmd(pmd_t *pmdp, pmd_t pmd, unsigned long addr, - unsigned long end, int write, struct page **pages, int *nr) -{ - struct page *head, *page; - unsigned long mask; - int refs; - - mask = (write ? _SEGMENT_ENTRY_PROTECT : 0) | _SEGMENT_ENTRY_INVALID; - if ((pmd_val(pmd) & mask) != 0) - return 0; - VM_BUG_ON(!pfn_valid(pmd_val(pmd) >> PAGE_SHIFT)); - - refs = 0; - head = pmd_page(pmd); - page = head + ((addr & ~PMD_MASK) >> PAGE_SHIFT); - do { - VM_BUG_ON(compound_head(page) != head); - pages[*nr] = page; - (*nr)++; - page++; - refs++; - } while (addr += PAGE_SIZE, addr != end); - - if (!page_cache_add_speculative(head, refs)) { - *nr -= refs; - return 0; - } - - if (unlikely(pmd_val(pmd) != pmd_val(*pmdp))) { - *nr -= refs; - while (refs--) - put_page(head); - return 0; - } - - return 1; -} - - -static inline int gup_pmd_range(pud_t pud, unsigned long addr, - unsigned long end, int write, struct page **pages, int *nr) -{ - unsigned long next; - pmd_t *pmdp, pmd; - - pmdp = pmd_offset(&pud, addr); - do { - pmd = *pmdp; - barrier(); - next = pmd_addr_end(addr, end); - if (pmd_none(pmd)) - return 0; - if (unlikely(pmd_large(pmd))) { - /* - * NUMA hinting faults need to be handled in the GUP - * slowpath for accounting purposes and so that they - * can be serialised against THP migration. - */ - if (pmd_protnone(pmd)) - return 0; - if (!gup_huge_pmd(pmdp, pmd, addr, next, - write, pages, nr)) - return 0; - } else if (!gup_pte_range(pmd, addr, next, - write, pages, nr)) - return 0; - } while (pmdp++, addr = next, addr != end); - - return 1; -} - -static int gup_huge_pud(pud_t *pudp, pud_t pud, unsigned long addr, - unsigned long end, int write, struct page **pages, int *nr) -{ - struct page *head, *page; - unsigned long mask; - int refs; - - mask = (write ? _REGION_ENTRY_PROTECT : 0) | _REGION_ENTRY_INVALID; - if ((pud_val(pud) & mask) != 0) - return 0; - VM_BUG_ON(!pfn_valid(pud_pfn(pud))); - - refs = 0; - head = pud_page(pud); - page = head + ((addr & ~PUD_MASK) >> PAGE_SHIFT); - do { - VM_BUG_ON_PAGE(compound_head(page) != head, page); - pages[*nr] = page; - (*nr)++; - page++; - refs++; - } while (addr += PAGE_SIZE, addr != end); - - if (!page_cache_add_speculative(head, refs)) { - *nr -= refs; - return 0; - } - - if (unlikely(pud_val(pud) != pud_val(*pudp))) { - *nr -= refs; - while (refs--) - put_page(head); - return 0; - } - - return 1; -} - -static inline int gup_pud_range(p4d_t p4d, unsigned long addr, - unsigned long end, int write, struct page **pages, int *nr) -{ - unsigned long next; - pud_t *pudp, pud; - - pudp = pud_offset(&p4d, addr); - do { - pud = *pudp; - barrier(); - next = pud_addr_end(addr, end); - if (pud_none(pud)) - return 0; - if (unlikely(pud_large(pud))) { - if (!gup_huge_pud(pudp, pud, addr, next, write, pages, - nr)) - return 0; - } else if (!gup_pmd_range(pud, addr, next, write, pages, - nr)) - return 0; - } while (pudp++, addr = next, addr != end); - - return 1; -} - -static inline int gup_p4d_range(pgd_t pgd, unsigned long addr, - unsigned long end, int write, struct page **pages, int *nr) -{ - unsigned long next; - p4d_t *p4dp, p4d; - - p4dp = p4d_offset(&pgd, addr); - do { - p4d = *p4dp; - barrier(); - next = p4d_addr_end(addr, end); - if (p4d_none(p4d)) - return 0; - if (!gup_pud_range(p4d, addr, next, write, pages, nr)) - return 0; - } while (p4dp++, addr = next, addr != end); - - return 1; -} - -/* - * Like get_user_pages_fast() except its IRQ-safe in that it won't fall - * back to the regular GUP. - * Note a difference with get_user_pages_fast: this always returns the - * number of pages pinned, 0 if no pages were pinned. - */ -int __get_user_pages_fast(unsigned long start, int nr_pages, int write, - struct page **pages) -{ - struct mm_struct *mm = current->mm; - unsigned long addr, len, end; - unsigned long next, flags; - pgd_t *pgdp, pgd; - int nr = 0; - - start &= PAGE_MASK; - addr = start; - len = (unsigned long) nr_pages << PAGE_SHIFT; - end = start + len; - if ((end <= start) || (end > mm->context.asce_limit)) - return 0; - /* - * local_irq_save() doesn't prevent pagetable teardown, but does - * prevent the pagetables from being freed on s390. - * - * So long as we atomically load page table pointers versus teardown, - * we can follow the address down to the the page and take a ref on it. - */ - local_irq_save(flags); - pgdp = pgd_offset(mm, addr); - do { - pgd = *pgdp; - barrier(); - next = pgd_addr_end(addr, end); - if (pgd_none(pgd)) - break; - if (!gup_p4d_range(pgd, addr, next, write, pages, &nr)) - break; - } while (pgdp++, addr = next, addr != end); - local_irq_restore(flags); - - return nr; -} - -/** - * get_user_pages_fast() - pin user pages in memory - * @start: starting user address - * @nr_pages: number of pages from start to pin - * @write: whether pages will be written to - * @pages: array that receives pointers to the pages pinned. - * Should be at least nr_pages long. - * - * Attempt to pin user pages in memory without taking mm->mmap_sem. - * If not successful, it will fall back to taking the lock and - * calling get_user_pages(). - * - * Returns number of pages pinned. This may be fewer than the number - * requested. If nr_pages is 0 or negative, returns 0. If no pages - * were pinned, returns -errno. - */ -int get_user_pages_fast(unsigned long start, int nr_pages, int write, - struct page **pages) -{ - int nr, ret; - - might_sleep(); - start &= PAGE_MASK; - nr = __get_user_pages_fast(start, nr_pages, write, pages); - if (nr == nr_pages) - return nr; - - /* Try to get the remaining pages with get_user_pages */ - start += nr << PAGE_SHIFT; - pages += nr; - ret = get_user_pages_unlocked(start, nr_pages - nr, pages, - write ? FOLL_WRITE : 0); - /* Have to be a bit careful with return values */ - if (nr > 0) - ret = (ret < 0) ? nr : ret + nr; - return ret; -}