Messages in this thread | | | From | Punit Agrawal <> | Subject | Re: [PATCH v2 2/3] arm64: hwpoison: add VM_FAULT_HWPOISON[_LARGE] handling | Date | Wed, 07 Jun 2017 18:47:05 +0100 |
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Will Deacon <will.deacon@arm.com> writes:
> On Wed, May 17, 2017 at 04:23:35PM +0100, Punit Agrawal wrote: >> From: "Jonathan (Zhixiong) Zhang" <zjzhang@codeaurora.org> >> >> Add VM_FAULT_HWPOISON[_LARGE] handling to the arm64 page fault >> handler. Handling of VM_FAULT_HWPOISON[_LARGE] is very similar >> to VM_FAULT_OOM, the only difference is that a different si_code >> (BUS_MCEERR_AR) is passed to user space and si_addr_lsb field is >> initialized. >> >> Signed-off-by: Jonathan (Zhixiong) Zhang <zjzhang@codeaurora.org> >> Signed-off-by: Tyler Baicar <tbaicar@codeaurora.org> >> (fix new __do_user_fault call-site) >> Signed-off-by: Punit Agrawal <punit.agrawal@arm.com> >> Acked-by: Steve Capper <steve.capper@arm.com> >> --- >> arch/arm64/mm/fault.c | 22 +++++++++++++++++++--- >> 1 file changed, 19 insertions(+), 3 deletions(-) >> >> diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c >> index 37b95dff0b07..a85b44343ac6 100644 >> --- a/arch/arm64/mm/fault.c >> +++ b/arch/arm64/mm/fault.c >> @@ -31,6 +31,7 @@ >> #include <linux/highmem.h> >> #include <linux/perf_event.h> >> #include <linux/preempt.h> >> +#include <linux/hugetlb.h> >> >> #include <asm/bug.h> >> #include <asm/cpufeature.h> >> @@ -239,10 +240,11 @@ static void __do_kernel_fault(struct mm_struct *mm, unsigned long addr, >> */ >> static void __do_user_fault(struct task_struct *tsk, unsigned long addr, >> unsigned int esr, unsigned int sig, int code, >> - struct pt_regs *regs) >> + struct pt_regs *regs, int fault) >> { >> struct siginfo si; >> const struct fault_info *inf; >> + unsigned int lsb = 0; >> >> if (unhandled_signal(tsk, sig) && show_unhandled_signals_ratelimited()) { >> inf = esr_to_fault_info(esr); >> @@ -259,6 +261,17 @@ static void __do_user_fault(struct task_struct *tsk, unsigned long addr, >> si.si_errno = 0; >> si.si_code = code; >> si.si_addr = (void __user *)addr; >> + /* >> + * Either small page or large page may be poisoned. >> + * In other words, VM_FAULT_HWPOISON_LARGE and >> + * VM_FAULT_HWPOISON are mutually exclusive. >> + */ >> + if (fault & VM_FAULT_HWPOISON_LARGE) >> + lsb = hstate_index_to_shift(VM_FAULT_GET_HINDEX(fault)); >> + else if (fault & VM_FAULT_HWPOISON) >> + lsb = PAGE_SHIFT; >> + si.si_addr_lsb = lsb; >> + > > If we're going to start handling poison faults, then we should probably > rejig the perf page fault accounting around here so that we follow x86: > > * Always report PERF_COUNT_SW_PAGE_FAULTS, > * Don't report anything else for VM_FAULT_ERROR > * Report PERF_COUNT_SW_PAGE_FAULTS_MAJ if VM_FAULT_MAJOR > * Otherwise, report PERF_COUNT_SW_PAGE_FAULTS_MIN > > at the moment, I think you're accounting VM_FAULT_ERROR as > PERF_COUNT_SW_PAGE_FAULTS_MIN, which doesn't feel right at all.
Ok. I'd missed the implication of enabling poisoned pages fault handling on the perf accounting. I'll add a patch to update the reporting.
> > Will
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