From 0b827537e339c084ac9384df588969d400be9e0d Mon Sep 17 00:00:00 2001 From: "venkatesh.pallipadi@intel.com" Date: Fri, 22 May 2009 13:23:37 -0700 Subject: x86: bugfix wbinvd() model check instead of family check wbinvd is supported on all CPUs 486 or later. But, pageattr.c is checking x86_model >= 4 before wbinvd(), which looks like an oversight bug. It was first introduced at one place by changeset d7c8f21a8cad0228c7c5ce2bb6dbd95d1ee49d13 and got copied over to second place in the same file later. [ Impact: fix missing cache flush on early-model CPUs, potential data corruption ] Signed-off-by: Venkatesh Pallipadi Signed-off-by: H. Peter Anvin --- arch/x86/mm/pageattr.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'arch/x86/mm') diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c index 797f9f107cb..2cc019a3f71 100644 --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -153,7 +153,7 @@ static void __cpa_flush_all(void *arg) */ __flush_tlb_all(); - if (cache && boot_cpu_data.x86_model >= 4) + if (cache && boot_cpu_data.x86 >= 4) wbinvd(); } @@ -218,7 +218,7 @@ static void cpa_flush_array(unsigned long *start, int numpages, int cache, /* 4M threshold */ if (numpages >= 1024) { - if (boot_cpu_data.x86_model >= 4) + if (boot_cpu_data.x86 >= 4) wbinvd(); return; } -- cgit v1.2.3-70-g09d2 From 0af48f42df15b97080b450d24219dd95db7b929a Mon Sep 17 00:00:00 2001 From: "venkatesh.pallipadi@intel.com" Date: Fri, 22 May 2009 13:23:38 -0700 Subject: x86: cpa_flush_array wbinvd should be done on all CPUs cpa_flush_array seems to prefer wbinvd() over clflush at 4M threshold. clflush needs to be done on only one CPU as per instruction definition. wbinvd() however, should be done on all CPUs. [ Impact: fix missing flush which could cause data corruption ] Signed-off-by: Venkatesh Pallipadi Signed-off-by: Suresh Siddha Signed-off-by: H. Peter Anvin --- arch/x86/mm/pageattr.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) (limited to 'arch/x86/mm') diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c index 2cc019a3f71..0f9052bcec4 100644 --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -204,6 +204,11 @@ static void cpa_flush_range(unsigned long start, int numpages, int cache) } } +static void wbinvd_local(void *unused) +{ + wbinvd(); +} + static void cpa_flush_array(unsigned long *start, int numpages, int cache, int in_flags, struct page **pages) { @@ -219,7 +224,8 @@ static void cpa_flush_array(unsigned long *start, int numpages, int cache, /* 4M threshold */ if (numpages >= 1024) { if (boot_cpu_data.x86 >= 4) - wbinvd(); + on_each_cpu(wbinvd_local, NULL, 1); + return; } /* -- cgit v1.2.3-70-g09d2 From 2171787be2e71ff71159857bfeb21398b61eb615 Mon Sep 17 00:00:00 2001 From: "Pallipadi, Venkatesh" Date: Tue, 26 May 2009 10:33:35 -0700 Subject: x86: avoid back to back on_each_cpu in cpa_flush_array Cleanup cpa_flush_array() to avoid back to back on_each_cpu() calls. [ Impact: optimizes fix 0af48f42df15b97080b450d24219dd95db7b929a ] Signed-off-by: Venkatesh Pallipadi Signed-off-by: H. Peter Anvin --- arch/x86/mm/pageattr.c | 17 +++-------------- 1 file changed, 3 insertions(+), 14 deletions(-) (limited to 'arch/x86/mm') diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c index 0f9052bcec4..e17efed088c 100644 --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -204,30 +204,19 @@ static void cpa_flush_range(unsigned long start, int numpages, int cache) } } -static void wbinvd_local(void *unused) -{ - wbinvd(); -} - static void cpa_flush_array(unsigned long *start, int numpages, int cache, int in_flags, struct page **pages) { unsigned int i, level; + unsigned long do_wbinvd = cache && numpages >= 1024; /* 4M threshold */ BUG_ON(irqs_disabled()); - on_each_cpu(__cpa_flush_range, NULL, 1); + on_each_cpu(__cpa_flush_all, (void *) do_wbinvd, 1); - if (!cache) + if (!cache || do_wbinvd) return; - /* 4M threshold */ - if (numpages >= 1024) { - if (boot_cpu_data.x86 >= 4) - on_each_cpu(wbinvd_local, NULL, 1); - - return; - } /* * We only need to flush on one CPU, * clflush is a MESI-coherent instruction that -- cgit v1.2.3-70-g09d2 From 32b154c0b0bae2879bf4e549d861caf1759a3546 Mon Sep 17 00:00:00 2001 From: Mel Gorman Date: Thu, 28 May 2009 14:34:37 -0700 Subject: x86: ignore VM_LOCKED when determining if hugetlb-backed page tables can be shared or not Addresses http://bugzilla.kernel.org/show_bug.cgi?id=13302 On x86 and x86-64, it is possible that page tables are shared beween shared mappings backed by hugetlbfs. As part of this, page_table_shareable() checks a pair of vma->vm_flags and they must match if they are to be shared. All VMA flags are taken into account, including VM_LOCKED. The problem is that VM_LOCKED is cleared on fork(). When a process with a shared memory segment forks() to exec() a helper, there will be shared VMAs with different flags. The impact is that the shared segment is sometimes considered shareable and other times not, depending on what process is checking. What happens is that the segment page tables are being shared but the count is inaccurate depending on the ordering of events. As the page tables are freed with put_page(), bad pmd's are found when some of the children exit. The hugepage counters also get corrupted and the Total and Free count will no longer match even when all the hugepage-backed regions are freed. This requires a reboot of the machine to "fix". This patch addresses the problem by comparing all flags except VM_LOCKED when deciding if pagetables should be shared or not for hugetlbfs-backed mapping. Signed-off-by: Mel Gorman Acked-by: Hugh Dickins Cc: Ingo Molnar Cc: Cc: Lee Schermerhorn Cc: KOSAKI Motohiro Cc: Cc: Eric B Munson Cc: Adam Litke Cc: Andy Whitcroft Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/x86/mm/hugetlbpage.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'arch/x86/mm') diff --git a/arch/x86/mm/hugetlbpage.c b/arch/x86/mm/hugetlbpage.c index 8f307d914c2..f46c340727b 100644 --- a/arch/x86/mm/hugetlbpage.c +++ b/arch/x86/mm/hugetlbpage.c @@ -26,12 +26,16 @@ static unsigned long page_table_shareable(struct vm_area_struct *svma, unsigned long sbase = saddr & PUD_MASK; unsigned long s_end = sbase + PUD_SIZE; + /* Allow segments to share if only one is marked locked */ + unsigned long vm_flags = vma->vm_flags & ~VM_LOCKED; + unsigned long svm_flags = svma->vm_flags & ~VM_LOCKED; + /* * match the virtual addresses, permission and the alignment of the * page table page. */ if (pmd_index(addr) != pmd_index(saddr) || - vma->vm_flags != svma->vm_flags || + vm_flags != svm_flags || sbase < svma->vm_start || svma->vm_end < s_end) return 0; -- cgit v1.2.3-70-g09d2