[PATCH 01/26] mm: Do page fault accounting in handle_mm_fault

Peter Xu
2020-06-19T16:07:17Z

This is a preparation patch to move page fault accountings into the general
code in handle_mm_fault(). This includes both the per task flt_maj/flt_min
counters, and the major/minor page fault perf events. To do this, the pt_regs
pointer is passed into handle_mm_fault().

PERF_COUNT_SW_PAGE_FAULTS should still be kept in per-arch page fault handlers.

So far, all the pt_regs pointer that passed into handle_mm_fault() is NULL,
which means this patch should have no intented functional change.

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Peter Xu <peterx@redhat.com>
---
arch/alpha/mm/fault.c | 2 +-
arch/arc/mm/fault.c | 2 +-
arch/arm/mm/fault.c | 2 +-
arch/arm64/mm/fault.c | 2 +-
arch/csky/mm/fault.c | 3 +-
arch/hexagon/mm/vm_fault.c | 2 +-
arch/ia64/mm/fault.c | 2 +-
arch/m68k/mm/fault.c | 2 +-
arch/microblaze/mm/fault.c | 2 +-
arch/mips/mm/fault.c | 2 +-
arch/nds32/mm/fault.c | 2 +-
arch/nios2/mm/fault.c | 2 +-
arch/openrisc/mm/fault.c | 2 +-
arch/parisc/mm/fault.c | 2 +-
arch/powerpc/mm/copro_fault.c | 2 +-
arch/powerpc/mm/fault.c | 2 +-
arch/riscv/mm/fault.c | 2 +-
arch/s390/mm/fault.c | 2 +-
arch/sh/mm/fault.c | 2 +-
arch/sparc/mm/fault_32.c | 4 +--
arch/sparc/mm/fault_64.c | 2 +-
arch/um/kernel/trap.c | 2 +-
arch/unicore32/mm/fault.c | 2 +-
arch/x86/mm/fault.c | 2 +-
arch/xtensa/mm/fault.c | 2 +-
drivers/iommu/amd_iommu_v2.c | 2 +-
drivers/iommu/intel-svm.c | 2 +-
include/linux/mm.h | 7 ++--
mm/gup.c | 4 +--
mm/hmm.c | 3 +-
mm/ksm.c | 3 +-
mm/memory.c | 66 ++++++++++++++++++++++++++++++++++-
32 files changed, 105 insertions(+), 35 deletions(-)

diff --git a/arch/alpha/mm/fault.c b/arch/alpha/mm/fault.c
index c2d7b6d7bac7..82e72f24486e 100644
--- a/arch/alpha/mm/fault.c
+++ b/arch/alpha/mm/fault.c
@@ -148,7 +148,7 @@ do_page_fault(unsigned long address, unsigned long mmcsr,
/* If for any reason at all we couldn't handle the fault,
make sure we exit gracefully rather than endlessly redo
the fault. */
- fault = handle_mm_fault(vma, address, flags);
+ fault = handle_mm_fault(vma, address, flags, NULL);

if (fault_signal_pending(fault, regs))
return;
diff --git a/arch/arc/mm/fault.c b/arch/arc/mm/fault.c
index 92b339c7adba..34380139e7a2 100644
--- a/arch/arc/mm/fault.c
+++ b/arch/arc/mm/fault.c
@@ -131,7 +131,7 @@ void do_page_fault(unsigned long address, struct pt_regs *regs)
goto bad_area;
}

- fault = handle_mm_fault(vma, address, flags);
+ fault = handle_mm_fault(vma, address, flags, NULL);

/* Quick path to respond to signals */
if (fault_signal_pending(fault, regs)) {
diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
index 2dd5c41cbb8d..0d6be0f4f27c 100644
--- a/arch/arm/mm/fault.c
+++ b/arch/arm/mm/fault.c
@@ -223,7 +223,7 @@ __do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
goto out;
}

- return handle_mm_fault(vma, addr & PAGE_MASK, flags);
+ return handle_mm_fault(vma, addr & PAGE_MASK, flags, NULL);

check_stack:
/* Don't allow expansion below FIRST_USER_ADDRESS */
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index c9cedc0432d2..5f6607b951b8 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -422,7 +422,7 @@ static vm_fault_t __do_page_fault(struct mm_struct *mm, unsigned long addr,
*/
if (!(vma->vm_flags & vm_flags))
return VM_FAULT_BADACCESS;
- return handle_mm_fault(vma, addr & PAGE_MASK, mm_flags);
+ return handle_mm_fault(vma, addr & PAGE_MASK, mm_flags, NULL);
}

static bool is_el0_instruction_abort(unsigned int esr)
diff --git a/arch/csky/mm/fault.c b/arch/csky/mm/fault.c
index 4e6dc68f3258..b14f97d3cb15 100644
--- a/arch/csky/mm/fault.c
+++ b/arch/csky/mm/fault.c
@@ -150,7 +150,8 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long write,
* make sure we exit gracefully rather than endlessly redo
* the fault.
*/
- fault = handle_mm_fault(vma, address, write ? FAULT_FLAG_WRITE : 0);
+ fault = handle_mm_fault(vma, address, write ? FAULT_FLAG_WRITE : 0,
+ NULL);
if (unlikely(fault & VM_FAULT_ERROR)) {
if (fault & VM_FAULT_OOM)
goto out_of_memory;
diff --git a/arch/hexagon/mm/vm_fault.c b/arch/hexagon/mm/vm_fault.c
index 72334b26317a..f04cd0a6d905 100644
--- a/arch/hexagon/mm/vm_fault.c
+++ b/arch/hexagon/mm/vm_fault.c
@@ -89,7 +89,7 @@ void do_page_fault(unsigned long address, long cause, struct pt_regs *regs)
break;
}

- fault = handle_mm_fault(vma, address, flags);
+ fault = handle_mm_fault(vma, address, flags, NULL);

if (fault_signal_pending(fault, regs))
return;
diff --git a/arch/ia64/mm/fault.c b/arch/ia64/mm/fault.c
index 30d0c1fca99e..caa93e083c9d 100644
--- a/arch/ia64/mm/fault.c
+++ b/arch/ia64/mm/fault.c
@@ -139,7 +139,7 @@ ia64_do_page_fault (unsigned long address, unsigned long isr, struct pt_regs *re
* sure we exit gracefully rather than endlessly redo the
* fault.
*/
- fault = handle_mm_fault(vma, address, flags);
+ fault = handle_mm_fault(vma, address, flags, NULL);

if (fault_signal_pending(fault, regs))
return;
diff --git a/arch/m68k/mm/fault.c b/arch/m68k/mm/fault.c
index 3bfb5c8ac3c7..2db38dfbc00c 100644
--- a/arch/m68k/mm/fault.c
+++ b/arch/m68k/mm/fault.c
@@ -135,7 +135,7 @@ int do_page_fault(struct pt_regs *regs, unsigned long address,
* the fault.
*/

- fault = handle_mm_fault(vma, address, flags);
+ fault = handle_mm_fault(vma, address, flags, NULL);
pr_debug("handle_mm_fault returns %x\n", fault);

if (fault_signal_pending(fault, regs))
diff --git a/arch/microblaze/mm/fault.c b/arch/microblaze/mm/fault.c
index 3248141f8ed5..9abfa5224386 100644
--- a/arch/microblaze/mm/fault.c
+++ b/arch/microblaze/mm/fault.c
@@ -215,7 +215,7 @@ void do_page_fault(struct pt_regs *regs, unsigned long address,
* make sure we exit gracefully rather than endlessly redo
* the fault.
*/
- fault = handle_mm_fault(vma, address, flags);
+ fault = handle_mm_fault(vma, address, flags, NULL);

if (fault_signal_pending(fault, regs))
return;
diff --git a/arch/mips/mm/fault.c b/arch/mips/mm/fault.c
index f8d62cd83b36..31c2afb8f8a5 100644
--- a/arch/mips/mm/fault.c
+++ b/arch/mips/mm/fault.c
@@ -152,7 +152,7 @@ static void __kprobes __do_page_fault(struct pt_regs *regs, unsigned long write,
* make sure we exit gracefully rather than endlessly redo
* the fault.
*/
- fault = handle_mm_fault(vma, address, flags);
+ fault = handle_mm_fault(vma, address, flags, NULL);

if (fault_signal_pending(fault, regs))
return;
diff --git a/arch/nds32/mm/fault.c b/arch/nds32/mm/fault.c
index f331e533edc2..22527129025c 100644
--- a/arch/nds32/mm/fault.c
+++ b/arch/nds32/mm/fault.c
@@ -207,7 +207,7 @@ void do_page_fault(unsigned long entry, unsigned long addr,
* the fault.
*/

- fault = handle_mm_fault(vma, addr, flags);
+ fault = handle_mm_fault(vma, addr, flags, NULL);

/*
* If we need to retry but a fatal signal is pending, handle the
diff --git a/arch/nios2/mm/fault.c b/arch/nios2/mm/fault.c
index ec9d8a9c426f..88abf297c759 100644
--- a/arch/nios2/mm/fault.c
+++ b/arch/nios2/mm/fault.c
@@ -131,7 +131,7 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long cause,
* make sure we exit gracefully rather than endlessly redo
* the fault.
*/
- fault = handle_mm_fault(vma, address, flags);
+ fault = handle_mm_fault(vma, address, flags, NULL);

if (fault_signal_pending(fault, regs))
return;
diff --git a/arch/openrisc/mm/fault.c b/arch/openrisc/mm/fault.c
index 8af1cc78c4fb..45aedc572361 100644
--- a/arch/openrisc/mm/fault.c
+++ b/arch/openrisc/mm/fault.c
@@ -159,7 +159,7 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long address,
* the fault.
*/

- fault = handle_mm_fault(vma, address, flags);
+ fault = handle_mm_fault(vma, address, flags, NULL);

if (fault_signal_pending(fault, regs))
return;
diff --git a/arch/parisc/mm/fault.c b/arch/parisc/mm/fault.c
index 86e8c848f3d7..c10908ea8803 100644
--- a/arch/parisc/mm/fault.c
+++ b/arch/parisc/mm/fault.c
@@ -302,7 +302,7 @@ void do_page_fault(struct pt_regs *regs, unsigned long code,
* fault.
*/

- fault = handle_mm_fault(vma, address, flags);
+ fault = handle_mm_fault(vma, address, flags, NULL);

if (fault_signal_pending(fault, regs))
return;
diff --git a/arch/powerpc/mm/copro_fault.c b/arch/powerpc/mm/copro_fault.c
index beb060b96632..c0478bef1f14 100644
--- a/arch/powerpc/mm/copro_fault.c
+++ b/arch/powerpc/mm/copro_fault.c
@@ -64,7 +64,7 @@ int copro_handle_mm_fault(struct mm_struct *mm, unsigned long ea,
}

ret = 0;
- *flt = handle_mm_fault(vma, ea, is_write ? FAULT_FLAG_WRITE : 0);
+ *flt = handle_mm_fault(vma, ea, is_write ? FAULT_FLAG_WRITE : 0, NULL);
if (unlikely(*flt & VM_FAULT_ERROR)) {
if (*flt & VM_FAULT_OOM) {
ret = -ENOMEM;
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 84af6c8eecf7..992b10c3761c 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -563,7 +563,7 @@ static int __do_page_fault(struct pt_regs *regs, unsigned long address,
* make sure we exit gracefully rather than endlessly redo
* the fault.
*/
- fault = handle_mm_fault(vma, address, flags);
+ fault = handle_mm_fault(vma, address, flags, NULL);

#ifdef CONFIG_PPC_MEM_KEYS
/*
diff --git a/arch/riscv/mm/fault.c b/arch/riscv/mm/fault.c
index be84e32adc4c..677ee1bb11ac 100644
--- a/arch/riscv/mm/fault.c
+++ b/arch/riscv/mm/fault.c
@@ -110,7 +110,7 @@ asmlinkage void do_page_fault(struct pt_regs *regs)
* make sure we exit gracefully rather than endlessly redo
* the fault.
*/
- fault = handle_mm_fault(vma, addr, flags);
+ fault = handle_mm_fault(vma, addr, flags, NULL);

/*
* If we need to retry but a fatal signal is pending, handle the
diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index dedc28be27ab..ab6d7eedcfab 100644
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -479,7 +479,7 @@ static inline vm_fault_t do_exception(struct pt_regs *regs, int access)
* make sure we exit gracefully rather than endlessly redo
* the fault.
*/
- fault = handle_mm_fault(vma, address, flags);
+ fault = handle_mm_fault(vma, address, flags, NULL);
if (fault_signal_pending(fault, regs)) {
fault = VM_FAULT_SIGNAL;
if (flags & FAULT_FLAG_RETRY_NOWAIT)
diff --git a/arch/sh/mm/fault.c b/arch/sh/mm/fault.c
index 5f23d7907597..a4e670a9c9b3 100644
--- a/arch/sh/mm/fault.c
+++ b/arch/sh/mm/fault.c
@@ -464,7 +464,7 @@ asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
* make sure we exit gracefully rather than endlessly redo
* the fault.
*/
- fault = handle_mm_fault(vma, address, flags);
+ fault = handle_mm_fault(vma, address, flags, NULL);

if (unlikely(fault & (VM_FAULT_RETRY | VM_FAULT_ERROR)))
if (mm_fault_error(regs, error_code, address, fault))
diff --git a/arch/sparc/mm/fault_32.c b/arch/sparc/mm/fault_32.c
index f6e0e601f857..61524d284706 100644
--- a/arch/sparc/mm/fault_32.c
+++ b/arch/sparc/mm/fault_32.c
@@ -235,7 +235,7 @@ asmlinkage void do_sparc_fault(struct pt_regs *regs, int text_fault, int write,
* make sure we exit gracefully rather than endlessly redo
* the fault.
*/
- fault = handle_mm_fault(vma, address, flags);
+ fault = handle_mm_fault(vma, address, flags, NULL);

if (fault_signal_pending(fault, regs))
return;
@@ -411,7 +411,7 @@ static void force_user_fault(unsigned long address, int write)
if (!(vma->vm_flags & (VM_READ | VM_EXEC)))
goto bad_area;
}
- switch (handle_mm_fault(vma, address, flags)) {
+ switch (handle_mm_fault(vma, address, flags, NULL)) {
case VM_FAULT_SIGBUS:
case VM_FAULT_OOM:
goto do_sigbus;
diff --git a/arch/sparc/mm/fault_64.c b/arch/sparc/mm/fault_64.c
index c0c0dd471b6b..6b702a0a8155 100644
--- a/arch/sparc/mm/fault_64.c
+++ b/arch/sparc/mm/fault_64.c
@@ -423,7 +423,7 @@ asmlinkage void __kprobes do_sparc64_fault(struct pt_regs *regs)
goto bad_area;
}

- fault = handle_mm_fault(vma, address, flags);
+ fault = handle_mm_fault(vma, address, flags, NULL);

if (fault_signal_pending(fault, regs))
goto exit_exception;
diff --git a/arch/um/kernel/trap.c b/arch/um/kernel/trap.c
index 8f18cf56b3dd..32cc8f59322b 100644
--- a/arch/um/kernel/trap.c
+++ b/arch/um/kernel/trap.c
@@ -75,7 +75,7 @@ int handle_page_fault(unsigned long address, unsigned long ip,
do {
vm_fault_t fault;

- fault = handle_mm_fault(vma, address, flags);
+ fault = handle_mm_fault(vma, address, flags, NULL);

if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
goto out_nosemaphore;
diff --git a/arch/unicore32/mm/fault.c b/arch/unicore32/mm/fault.c
index 3022104aa613..847ff24fcc2a 100644
--- a/arch/unicore32/mm/fault.c
+++ b/arch/unicore32/mm/fault.c
@@ -186,7 +186,7 @@ static vm_fault_t __do_pf(struct mm_struct *mm, unsigned long addr,
* If for any reason at all we couldn't handle the fault, make
* sure we exit gracefully rather than endlessly redo the fault.
*/
- fault = handle_mm_fault(vma, addr & PAGE_MASK, flags);
+ fault = handle_mm_fault(vma, addr & PAGE_MASK, flags, NULL);
return fault;

check_stack:
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index a51df516b87b..3e27ed85af06 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -1461,7 +1461,7 @@ void do_user_addr_fault(struct pt_regs *regs,
* userland). The return to userland is identified whenever
* FAULT_FLAG_USER|FAULT_FLAG_KILLABLE are both set in flags.
*/
- fault = handle_mm_fault(vma, address, flags);
+ fault = handle_mm_fault(vma, address, flags, NULL);
major |= fault & VM_FAULT_MAJOR;

/* Quick path to respond to signals */
diff --git a/arch/xtensa/mm/fault.c b/arch/xtensa/mm/fault.c
index e7172bd53ced..722ef3c98d60 100644
--- a/arch/xtensa/mm/fault.c
+++ b/arch/xtensa/mm/fault.c
@@ -108,7 +108,7 @@ void do_page_fault(struct pt_regs *regs)
* make sure we exit gracefully rather than endlessly redo
* the fault.
*/
- fault = handle_mm_fault(vma, address, flags);
+ fault = handle_mm_fault(vma, address, flags, NULL);

if (fault_signal_pending(fault, regs))
return;
diff --git a/drivers/iommu/amd_iommu_v2.c b/drivers/iommu/amd_iommu_v2.c
index d6d85debd01b..66042b816943 100644
--- a/drivers/iommu/amd_iommu_v2.c
+++ b/drivers/iommu/amd_iommu_v2.c
@@ -497,7 +497,7 @@ static void do_fault(struct work_struct *work)
if (access_error(vma, fault))
goto out;

- ret = handle_mm_fault(vma, address, flags);
+ ret = handle_mm_fault(vma, address, flags, NULL);
out:
up_read(&mm->mmap_sem);

diff --git a/drivers/iommu/intel-svm.c b/drivers/iommu/intel-svm.c
index 2998418f0a38..c9cb5e5b6c34 100644
--- a/drivers/iommu/intel-svm.c
+++ b/drivers/iommu/intel-svm.c
@@ -629,7 +629,7 @@ static irqreturn_t prq_event_thread(int irq, void *d)
goto invalid;

ret = handle_mm_fault(vma, address,
- req->wr_req ? FAULT_FLAG_WRITE : 0);
+ req->wr_req ? FAULT_FLAG_WRITE : 0, NULL);
if (ret & VM_FAULT_ERROR)
goto invalid;

diff --git a/include/linux/mm.h b/include/linux/mm.h
index f3fe7371855c..46bee4044ac1 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -36,6 +36,7 @@ struct file_ra_state;
struct user_struct;
struct writeback_control;
struct bdi_writeback;
+struct pt_regs;

void init_mm_internals(void);

@@ -1652,7 +1653,8 @@ int invalidate_inode_page(struct page *page);

#ifdef CONFIG_MMU
extern vm_fault_t handle_mm_fault(struct vm_area_struct *vma,
- unsigned long address, unsigned int flags);
+ unsigned long address, unsigned int flags,
+ struct pt_regs *regs);
extern int fixup_user_fault(struct task_struct *tsk, struct mm_struct *mm,
unsigned long address, unsigned int fault_flags,
bool *unlocked);
@@ -1662,7 +1664,8 @@ void unmap_mapping_range(struct address_space *mapping,
loff_t const holebegin, loff_t const holelen, int even_cows);
#else
static inline vm_fault_t handle_mm_fault(struct vm_area_struct *vma,
- unsigned long address, unsigned int flags)
+ unsigned long address, unsigned int flags,
+ struct pt_regs *regs)
{
/* should never happen if there's no MMU */
BUG();
diff --git a/mm/gup.c b/mm/gup.c
index 87a6a59fe667..1a48c639ea49 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -876,7 +876,7 @@ static int faultin_page(struct task_struct *tsk, struct vm_area_struct *vma,
fault_flags |= FAULT_FLAG_TRIED;
}

- ret = handle_mm_fault(vma, address, fault_flags);
+ ret = handle_mm_fault(vma, address, fault_flags, NULL);
if (ret & VM_FAULT_ERROR) {
int err = vm_fault_to_errno(ret, *flags);

@@ -1222,7 +1222,7 @@ int fixup_user_fault(struct task_struct *tsk, struct mm_struct *mm,
fatal_signal_pending(current))
return -EINTR;

- ret = handle_mm_fault(vma, address, fault_flags);
+ ret = handle_mm_fault(vma, address, fault_flags, NULL);
major |= ret & VM_FAULT_MAJOR;
if (ret & VM_FAULT_ERROR) {
int err = vm_fault_to_errno(ret, 0);
diff --git a/mm/hmm.c b/mm/hmm.c
index 280585833adf..5fca59a1f6e9 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -90,7 +90,8 @@ static int hmm_vma_fault(unsigned long addr, unsigned long end,
}

for (; addr < end; addr += PAGE_SIZE)
- if (handle_mm_fault(vma, addr, fault_flags) & VM_FAULT_ERROR)
+ if (handle_mm_fault(vma, addr, fault_flags, NULL) &
+ VM_FAULT_ERROR)
return -EFAULT;
return -EBUSY;
}
diff --git a/mm/ksm.c b/mm/ksm.c
index 281c00129a2e..2e2b02abcc0f 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -480,7 +480,8 @@ static int break_ksm(struct vm_area_struct *vma, unsigned long addr)
break;
if (PageKsm(page))
ret = handle_mm_fault(vma, addr,
- FAULT_FLAG_WRITE | FAULT_FLAG_REMOTE);
+ FAULT_FLAG_WRITE | FAULT_FLAG_REMOTE,
+ NULL);
else
ret = VM_FAULT_WRITE;
put_page(page);
diff --git a/mm/memory.c b/mm/memory.c
index f703fe8c8346..23c738b3756e 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -71,6 +71,8 @@
#include <linux/dax.h>
#include <linux/oom.h>
#include <linux/numa.h>
+#include <linux/perf_event.h>
+#include <linux/ptrace.h>

#include <trace/events/kmem.h>

@@ -4345,6 +4347,36 @@ static vm_fault_t __handle_mm_fault(struct vm_area_struct *vma,
return handle_pte_fault(&vmf);
}

+/**
+ * mm_account_fault - Do page fault accountings
+ * @regs: the pt_regs struct pointer. When set to NULL, will skip accounting
+ * @address: faulted address.
+ * @major: whether this is a major fault.
+ *
+ * This will take care of most of the page fault accountings. It should only
+ * be called when a page fault is completed. For example, VM_FAULT_RETRY means
+ * the fault needs to be retried again later, so it should not contribute to
+ * the accounting.
+ *
+ * The accounting will also include the PERF_COUNT_SW_PAGE_FAULTS_[MAJ|MIN]
+ * perf counter updates. Note: the handling of PERF_COUNT_SW_PAGE_FAULTS
+ * should still be in per-arch page fault handlers at the entry of page fault.
+ */
+static inline void mm_account_fault(struct pt_regs *regs,
+ unsigned long address, bool major)
+{
+ if (!regs)
+ return;
+
+ if (major) {
+ current->maj_flt++;
+ perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs, address);
+ } else {
+ current->min_flt++;
+ perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs, address);
+ }
+}
+
/*
* By the time we get here, we already hold the mm semaphore
*
@@ -4352,7 +4384,7 @@ static vm_fault_t __handle_mm_fault(struct vm_area_struct *vma,
* return value. See filemap_fault() and __lock_page_or_retry().
*/
vm_fault_t handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
- unsigned int flags)
+ unsigned int flags, struct pt_regs *regs)
{
vm_fault_t ret;

@@ -4393,6 +4425,38 @@ vm_fault_t handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
mem_cgroup_oom_synchronize(false);
}

+ if (ret & VM_FAULT_RETRY)
+ return ret;
+
+ /*
+ * Do accounting in the common code, to avoid unnecessary
+ * architecture differences or duplicated code.
+ *
+ * We arbitrarily make the rules be:
+ *
+ * - faults that never even got here (because the address
+ * wasn't valid). That includes arch_vma_access_permitted()
+ * failing above.
+ *
+ * So this is expressly not a "this many hardware page
+ * faults" counter. Use the hw profiling for that.
+ *
+ * - incomplete faults (ie RETRY) do not count (see above).
+ * They will only count once completed.
+ *
+ * - the fault counts as a "major" fault when the final
+ * successful fault is VM_FAULT_MAJOR, or if it was a
+ * retry (which implies that we couldn't handle it
+ * immediately previously).
+ *
+ * - if the fault is done for GUP, regs wil be NULL and
+ * no accounting will be done (but you _could_ pass in
+ * your own regs and it would be accounted to the thread
+ * doing the fault, not to the target!)
+ */
+ mm_account_fault(regs, address, (ret & VM_FAULT_MAJOR) ||
+ (flags & FAULT_FLAG_TRIED));
+
return ret;
}
EXPORT_SYMBOL_GPL(handle_mm_fault);
--
2.26.2