From 9b79022ca909b66e2cd0cfd9248f832fc165f77f Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Mon, 28 Jul 2008 17:54:21 -0700 Subject: Fix 'get_user_pages_fast()' with non-page-aligned start address Alexey Dobriyan reported trouble with LTP with the new fast-gup code, and Johannes Weiner debugged it to non-page-aligned addresses, where the new get_user_pages_fast() code would do all the wrong things, including just traversing past the end of the requested area due to 'addr' never matching 'end' exactly. This is not a pretty fix, and we may actually want to move the alignment into generic code, leaving just the core code per-arch, but Alexey verified that the vmsplice01 LTP test doesn't crash with this. Reported-and-tested-by: Alexey Dobriyan Debugged-by: Johannes Weiner Cc: Nick Piggin Cc: Andrew Morton Signed-off-by: Linus Torvalds --- arch/x86/mm/gup.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) (limited to 'arch/x86/mm') diff --git a/arch/x86/mm/gup.c b/arch/x86/mm/gup.c index 3085f25b435..007bb06c750 100644 --- a/arch/x86/mm/gup.c +++ b/arch/x86/mm/gup.c @@ -223,14 +223,17 @@ int get_user_pages_fast(unsigned long start, int nr_pages, int write, struct page **pages) { struct mm_struct *mm = current->mm; - unsigned long end = start + (nr_pages << PAGE_SHIFT); - unsigned long addr = start; + unsigned long addr, len, end; unsigned long next; pgd_t *pgdp; int nr = 0; + start &= PAGE_MASK; + addr = start; + len = (unsigned long) nr_pages << PAGE_SHIFT; + end = start + len; if (unlikely(!access_ok(write ? VERIFY_WRITE : VERIFY_READ, - start, nr_pages*PAGE_SIZE))) + start, len))) goto slow_irqon; /* -- cgit v1.2.3 From cf3e50501259f9a7cb108a69c3e1b912135628f6 Mon Sep 17 00:00:00 2001 From: Jeremy Fitzhardinge Date: Fri, 8 Aug 2008 13:46:07 -0700 Subject: x86: work around gcc 3.4.x bug Simon Horman reported that gcc-3.4.x crashes when compiling pgd_prepopulate_pmd() when PREALLOCATED_PMDS == 0 and CONFIG_DEBUG_INFO is enabled. Adding an extra check for PREALLOCATED_PMDS == 0 [which is compiled out by gcc] seems to avoid the problem. Reported-by: Simon Horman Signed-off-by: Jeremy Fitzhardinge Acked-by: Simon Horman Signed-off-by: Ingo Molnar --- arch/x86/mm/pgtable.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'arch/x86/mm') diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c index 557b2abceef..d50302774fe 100644 --- a/arch/x86/mm/pgtable.c +++ b/arch/x86/mm/pgtable.c @@ -207,6 +207,9 @@ static void pgd_prepopulate_pmd(struct mm_struct *mm, pgd_t *pgd, pmd_t *pmds[]) unsigned long addr; int i; + if (PREALLOCATED_PMDS == 0) /* Work around gcc-3.4.x bug */ + return; + pud = pud_offset(pgd, 0); for (addr = i = 0; i < PREALLOCATED_PMDS; -- cgit v1.2.3 From 912985dce45ef18fcdd9f5439fef054e0e22302a Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Tue, 12 Aug 2008 17:52:52 -0500 Subject: mm: Make generic weak get_user_pages_fast and EXPORT_GPL it Out of line get_user_pages_fast fallback implementation, make it a weak symbol, get rid of CONFIG_HAVE_GET_USER_PAGES_FAST. Export the symbol to modules so lguest can use it. Signed-off-by: Nick Piggin Signed-off-by: Rusty Russell --- arch/x86/mm/Makefile | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) (limited to 'arch/x86/mm') diff --git a/arch/x86/mm/Makefile b/arch/x86/mm/Makefile index 2977ea37791..dfb932dcf13 100644 --- a/arch/x86/mm/Makefile +++ b/arch/x86/mm/Makefile @@ -1,7 +1,6 @@ obj-y := init_$(BITS).o fault.o ioremap.o extable.o pageattr.o mmap.o \ - pat.o pgtable.o + pat.o pgtable.o gup.o -obj-$(CONFIG_HAVE_GET_USER_PAGES_FAST) += gup.o obj-$(CONFIG_X86_32) += pgtable_32.o obj-$(CONFIG_HUGETLB_PAGE) += hugetlbpage.o -- cgit v1.2.3