Commit a0715cc2 authored by Alex Thorlton's avatar Alex Thorlton Committed by Linus Torvalds
Browse files

mm, thp: add VM_INIT_DEF_MASK and PRCTL_THP_DISABLE 



Add VM_INIT_DEF_MASK, to allow us to set the default flags for VMs.  It
also adds a prctl control which allows us to set the THP disable bit in
mm->def_flags so that VMs will pick up the setting as they are created.

Signed-off-by: default avatarAlex Thorlton <athorlton@sgi.com>
Suggested-by: default avatarOleg Nesterov <oleg@redhat.com>
Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Acked-by: default avatarRik van Riel <riel@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 1e1836e8

include/linux/mm.h

+3 −0
Original line number Diff line number Diff line
@@ -177,6 +177,9 @@ extern unsigned int kobjsize(const void *objp); 
 */

#define VM_SPECIAL (VM_IO | VM_DONTEXPAND | VM_PFNMAP | VM_MIXEDMAP)



/* This mask defines which mm->def_flags a process can inherit its parent */

#define VM_INIT_DEF_MASK	VM_NOHUGEPAGE



/*

 * mapping from the currently active vm_flags protection bits (the

 * low four bits) to a page protection mask..

include/uapi/linux/prctl.h

+3 −0
Original line number Diff line number Diff line
@@ -149,4 +149,7 @@ 


#define PR_GET_TID_ADDRESS	40



#define PR_SET_THP_DISABLE	41

#define PR_GET_THP_DISABLE	42



#endif /* _LINUX_PRCTL_H */

kernel/fork.c

+8 −3
Original line number Diff line number Diff line
@@ -530,8 +530,6 @@ static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p) 
	atomic_set(&mm->mm_count, 1);

	init_rwsem(&mm->mmap_sem);

	INIT_LIST_HEAD(&mm->mmlist);

	mm->flags = (current->mm) ?

		(current->mm->flags & MMF_INIT_MASK) : default_dump_filter;

	mm->core_state = NULL;

	atomic_long_set(&mm->nr_ptes, 0);

	memset(&mm->rss_stat, 0, sizeof(mm->rss_stat));
@@ -540,8 +538,15 @@ static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p) 
	mm_init_owner(mm, p);

	clear_tlb_flush_pending(mm);



	if (likely(!mm_alloc_pgd(mm))) {

	if (current->mm) {

		mm->flags = current->mm->flags & MMF_INIT_MASK;

		mm->def_flags = current->mm->def_flags & VM_INIT_DEF_MASK;

	} else {

		mm->flags = default_dump_filter;

		mm->def_flags = 0;

	}



	if (likely(!mm_alloc_pgd(mm))) {

		mmu_notifier_mm_init(mm);

		return mm;

	}

kernel/sys.c

+15 −0
Original line number Diff line number Diff line
@@ -1996,6 +1996,21 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3, 
		if (arg2 || arg3 || arg4 || arg5)

			return -EINVAL;

		return current->no_new_privs ? 1 : 0;

	case PR_GET_THP_DISABLE:

		if (arg2 || arg3 || arg4 || arg5)

			return -EINVAL;

		error = !!(me->mm->def_flags & VM_NOHUGEPAGE);

		break;

	case PR_SET_THP_DISABLE:

		if (arg3 || arg4 || arg5)

			return -EINVAL;

		down_write(&me->mm->mmap_sem);

		if (arg2)

			me->mm->def_flags |= VM_NOHUGEPAGE;

		else

			me->mm->def_flags &= ~VM_NOHUGEPAGE;

		up_write(&me->mm->mmap_sem);

		break;

	default:

		error = -EINVAL;

		break;

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