Commit 68f48381 authored by Suren Baghdasaryan's avatar Suren Baghdasaryan Committed by Andrew Morton
Browse files

mm: introduce __vm_flags_mod and use it in untrack_pfn 

There are scenarios when vm_flags can be modified without exclusive
mmap_lock, such as:
- after VMA was isolated and mmap_lock was downgraded or dropped
- in exit_mmap when there are no other mm users and locking is unnecessary
Introduce __vm_flags_mod to avoid assertions when the caller takes
responsibility for the required locking.
Pass a hint to untrack_pfn to conditionally use __vm_flags_mod for
flags modification to avoid assertion.

Link: https://lkml.kernel.org/r/20230126193752.297968-7-surenb@google.com


Signed-off-by: default avatarSuren Baghdasaryan <surenb@google.com>
Acked-by: default avatarMichal Hocko <mhocko@suse.com>
Acked-by: default avatarMike Rapoport (IBM) <rppt@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arjun Roy <arjunroy@google.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: David Rientjes <rientjes@google.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Laurent Dufour <ldufour@linux.ibm.com>
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Minchan Kim <minchan@google.com>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Peter Oskolkov <posk@google.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Punit Agrawal <punit.agrawal@bytedance.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Sebastian Reichel <sebastian.reichel@collabora.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Soheil Hassas Yeganeh <soheil@google.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent ff126c0e

arch/x86/mm/pat/memtype.c

+7 −3
Original line number Diff line number Diff line
@@ -1046,7 +1046,7 @@ void track_pfn_insert(struct vm_area_struct *vma, pgprot_t *prot, pfn_t pfn) 
 * can be for the entire vma (in which case pfn, size are zero).

 */

void untrack_pfn(struct vm_area_struct *vma, unsigned long pfn,

		 unsigned long size)

		 unsigned long size, bool mm_wr_locked)

{

	resource_size_t paddr;

	unsigned long prot;
@@ -1065,8 +1065,12 @@ void untrack_pfn(struct vm_area_struct *vma, unsigned long pfn, 
		size = vma->vm_end - vma->vm_start;

	}

	free_pfn_range(paddr, size);

	if (vma)

	if (vma) {

		if (mm_wr_locked)

			vm_flags_clear(vma, VM_PAT);

		else

			__vm_flags_mod(vma, 0, VM_PAT);

	}

}



/*

include/linux/mm.h

+12 −2
Original line number Diff line number Diff line
@@ -656,6 +656,16 @@ static inline void vm_flags_clear(struct vm_area_struct *vma, 
	ACCESS_PRIVATE(vma, __vm_flags) &= ~flags;

}



/*

 * Use only if VMA is not part of the VMA tree or has no other users and

 * therefore needs no locking.

 */

static inline void __vm_flags_mod(struct vm_area_struct *vma,

				  vm_flags_t set, vm_flags_t clear)

{

	vm_flags_init(vma, (vma->vm_flags | set) & ~clear);

}



/*

 * Use only when the order of set/clear operations is unimportant, otherwise

 * use vm_flags_{set|clear} explicitly.
@@ -664,7 +674,7 @@ static inline void vm_flags_mod(struct vm_area_struct *vma, 
				vm_flags_t set, vm_flags_t clear)

{

	mmap_assert_write_locked(vma->vm_mm);

	vm_flags_init(vma, (vma->vm_flags | set) & ~clear);

	__vm_flags_mod(vma, set, clear);

}



static inline void vma_set_anonymous(struct vm_area_struct *vma)
@@ -2085,7 +2095,7 @@ static inline void zap_vma_pages(struct vm_area_struct *vma) 
}

void unmap_vmas(struct mmu_gather *tlb, struct maple_tree *mt,

		struct vm_area_struct *start_vma, unsigned long start,

		unsigned long end);

		unsigned long end, bool mm_wr_locked);



struct mmu_notifier_range;

include/linux/pgtable.h

+3 −2
Original line number Diff line number Diff line
@@ -1185,7 +1185,8 @@ static inline int track_pfn_copy(struct vm_area_struct *vma) 
 * can be for the entire vma (in which case pfn, size are zero).

 */

static inline void untrack_pfn(struct vm_area_struct *vma,

			       unsigned long pfn, unsigned long size)

			       unsigned long pfn, unsigned long size,

			       bool mm_wr_locked)

{

}
@@ -1203,7 +1204,7 @@ extern void track_pfn_insert(struct vm_area_struct *vma, pgprot_t *prot, 
			     pfn_t pfn);

extern int track_pfn_copy(struct vm_area_struct *vma);

extern void untrack_pfn(struct vm_area_struct *vma, unsigned long pfn,

			unsigned long size);

			unsigned long size, bool mm_wr_locked);

extern void untrack_pfn_moved(struct vm_area_struct *vma);

#endif

mm/memory.c

+7 −6
Original line number Diff line number Diff line
@@ -1613,7 +1613,7 @@ void unmap_page_range(struct mmu_gather *tlb, 
static void unmap_single_vma(struct mmu_gather *tlb,

		struct vm_area_struct *vma, unsigned long start_addr,

		unsigned long end_addr,

		struct zap_details *details)

		struct zap_details *details, bool mm_wr_locked)

{

	unsigned long start = max(vma->vm_start, start_addr);

	unsigned long end;
@@ -1628,7 +1628,7 @@ static void unmap_single_vma(struct mmu_gather *tlb, 
		uprobe_munmap(vma, start, end);



	if (unlikely(vma->vm_flags & VM_PFNMAP))

		untrack_pfn(vma, 0, 0);

		untrack_pfn(vma, 0, 0, mm_wr_locked);



	if (start != end) {

		if (unlikely(is_vm_hugetlb_page(vma))) {
@@ -1675,7 +1675,7 @@ static void unmap_single_vma(struct mmu_gather *tlb, 
 */

void unmap_vmas(struct mmu_gather *tlb, struct maple_tree *mt,

		struct vm_area_struct *vma, unsigned long start_addr,

		unsigned long end_addr)

		unsigned long end_addr, bool mm_wr_locked)

{

	struct mmu_notifier_range range;

	struct zap_details details = {
@@ -1689,7 +1689,8 @@ void unmap_vmas(struct mmu_gather *tlb, struct maple_tree *mt, 
				start_addr, end_addr);

	mmu_notifier_invalidate_range_start(&range);

	do {

		unmap_single_vma(tlb, vma, start_addr, end_addr, &details);

		unmap_single_vma(tlb, vma, start_addr, end_addr, &details,

				 mm_wr_locked);

	} while ((vma = mas_find(&mas, end_addr - 1)) != NULL);

	mmu_notifier_invalidate_range_end(&range);

}
@@ -1723,7 +1724,7 @@ void zap_page_range_single(struct vm_area_struct *vma, unsigned long address, 
	 * unmap 'address-end' not 'range.start-range.end' as range

	 * could have been expanded for hugetlb pmd sharing.

	 */

	unmap_single_vma(&tlb, vma, address, end, details);

	unmap_single_vma(&tlb, vma, address, end, details, false);

	mmu_notifier_invalidate_range_end(&range);

	tlb_finish_mmu(&tlb);

}
@@ -2492,7 +2493,7 @@ int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr, 


	err = remap_pfn_range_notrack(vma, addr, pfn, size, prot);

	if (err)

		untrack_pfn(vma, pfn, PAGE_ALIGN(size));

		untrack_pfn(vma, pfn, PAGE_ALIGN(size), true);

	return err;

}

EXPORT_SYMBOL(remap_pfn_range);

mm/memremap.c

+2 −2
Original line number Diff line number Diff line
@@ -129,7 +129,7 @@ static void pageunmap_range(struct dev_pagemap *pgmap, int range_id) 
	}

	mem_hotplug_done();



	untrack_pfn(NULL, PHYS_PFN(range->start), range_len(range));

	untrack_pfn(NULL, PHYS_PFN(range->start), range_len(range), true);

	pgmap_array_delete(range);

}
@@ -276,7 +276,7 @@ static int pagemap_range(struct dev_pagemap *pgmap, struct mhp_params *params, 
	if (!is_private)

		kasan_remove_zero_shadow(__va(range->start), range_len(range));

err_kasan:

	untrack_pfn(NULL, PHYS_PFN(range->start), range_len(range));

	untrack_pfn(NULL, PHYS_PFN(range->start), range_len(range), true);

err_pfn_remap:

	pgmap_array_delete(range);

	return error;