Commit e06f47a1 authored by Heiko Carstens's avatar Heiko Carstens Committed by Andrew Morton
Browse files

s390/mm: try VMA lock-based page fault handling first 

Attempt VMA lock-based page fault handling first, and fall back to the
existing mmap_lock-based handling if that fails.

This is the s390 variant of "x86/mm: try VMA lock-based page fault handling
first".

Link: https://lkml.kernel.org/r/20230314132808.1266335-1-hca@linux.ibm.com


Signed-off-by: default avatarHeiko Carstens <hca@linux.ibm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent c7f8f31c

arch/s390/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -120,6 +120,7 @@ config S390 
	select ARCH_SUPPORTS_DEBUG_PAGEALLOC

	select ARCH_SUPPORTS_HUGETLBFS

	select ARCH_SUPPORTS_NUMA_BALANCING

	select ARCH_SUPPORTS_PER_VMA_LOCK

	select ARCH_USE_BUILTIN_BSWAP

	select ARCH_USE_CMPXCHG_LOCKREF

	select ARCH_WANTS_DYNAMIC_TASK_STRUCT

arch/s390/mm/fault.c

+24 −0
Original line number Diff line number Diff line
@@ -407,6 +407,30 @@ static inline vm_fault_t do_exception(struct pt_regs *regs, int access) 
		access = VM_WRITE;

	if (access == VM_WRITE)

		flags |= FAULT_FLAG_WRITE;

#ifdef CONFIG_PER_VMA_LOCK

	if (!(flags & FAULT_FLAG_USER))

		goto lock_mmap;

	vma = lock_vma_under_rcu(mm, address);

	if (!vma)

		goto lock_mmap;

	if (!(vma->vm_flags & access)) {

		vma_end_read(vma);

		goto lock_mmap;

	}

	fault = handle_mm_fault(vma, address, flags | FAULT_FLAG_VMA_LOCK, regs);

	vma_end_read(vma);

	if (!(fault & VM_FAULT_RETRY)) {

		count_vm_vma_lock_event(VMA_LOCK_SUCCESS);

		goto out;

	}

	count_vm_vma_lock_event(VMA_LOCK_RETRY);

	/* Quick path to respond to signals */

	if (fault_signal_pending(fault, regs)) {

		fault = VM_FAULT_SIGNAL;

		goto out;

	}

lock_mmap:

#endif /* CONFIG_PER_VMA_LOCK */

	mmap_read_lock(mm);



	gmap = NULL;