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mm/arm: use general page fault accounting

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Use the general page fault accounting by passing regs into
handle_mm_fault().  It naturally solve the issue of multiple page fault
accounting when page fault retry happened.  To do this, we need to pass
the pt_regs pointer into __do_page_fault().

Fix PERF_COUNT_SW_PAGE_FAULTS perf event manually for page fault retries,
by moving it before taking mmap_sem.

Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Will Deacon <will@kernel.org>
Link: http://lkml.kernel.org/r/20200707225021.200906-5-peterx@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Peter Xu 2020-08-11 18:37:54 -07:00 committed by Linus Torvalds
parent 52e3f8d030
commit 79fea6c654
1 changed files with 6 additions and 19 deletions
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25
arch/arm/mm/fault.c
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@ -202,7 +202,8 @@ static inline bool access_error(unsigned int fsr, struct vm_area_struct *vma)
static vm_fault_t __kprobes
__do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
unsigned int flags, struct task_struct *tsk)
unsigned int flags, struct task_struct *tsk,
struct pt_regs *regs)
{
struct vm_area_struct *vma;
vm_fault_t fault;
@ -224,7 +225,7 @@ __do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
goto out;
}
return handle_mm_fault(vma, addr & PAGE_MASK, flags, NULL);
return handle_mm_fault(vma, addr & PAGE_MASK, flags, regs);
check_stack:
/* Don't allow expansion below FIRST_USER_ADDRESS */
@ -266,6 +267,8 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
if ((fsr & FSR_WRITE) && !(fsr & FSR_CM))
flags |= FAULT_FLAG_WRITE;
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
/*
* As per x86, we may deadlock here. However, since the kernel only
* validly references user space from well defined areas of the code,
@ -290,7 +293,7 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
#endif
}
fault = __do_page_fault(mm, addr, fsr, flags, tsk);
fault = __do_page_fault(mm, addr, fsr, flags, tsk, regs);
/* If we need to retry but a fatal signal is pending, handle the
* signal first. We do not need to release the mmap_lock because
@ -302,23 +305,7 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
return 0;
}
/*
* Major/minor page fault accounting is only done on the
* initial attempt. If we go through a retry, it is extremely
* likely that the page will be found in page cache at that point.
*/
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
if (!(fault & VM_FAULT_ERROR) && flags & FAULT_FLAG_ALLOW_RETRY) {
if (fault & VM_FAULT_MAJOR) {
tsk->maj_flt++;
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
regs, addr);
} else {
tsk->min_flt++;
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
regs, addr);
}
if (fault & VM_FAULT_RETRY) {
flags |= FAULT_FLAG_TRIED;
goto retry;