mm: do not initialize TLB stack vma's with vma_init()
Commit 2c4541e24c55 ("mm: use vma_init() to initialize VMAs on stack and
data segments") tried to initialize various left-over ad-hoc vma's
"properly", but actually made things worse for the temporary vma's used
for TLB flushing.
vma_init() doesn't actually initialize all of the vma, just a few
fields, so doing something like
- struct vm_area_struct vma = { .vm_mm = tlb->mm, };
+ struct vm_area_struct vma;
+
+ vma_init(&vma, tlb->mm);
was actually very bad: instead of having a nicely initialized vma with
every field but "vm_mm" zeroed, you'd have an entirely uninitialized vma
with only a couple of fields initialized. And they weren't even fields
that the code in question mostly cared about.
The flush_tlb_range() function takes a "struct vma" rather than a
"struct mm_struct", because a few architectures actually care about what
kind of range it is - being able to only do an ITLB flush if it's a
range that doesn't have data accesses enabled, for example. And all the
normal users already have the vma for doing the range invalidation.
But a few people want to call flush_tlb_range() with a range they just
made up, so they also end up using a made-up vma. x86 just has a
special "flush_tlb_mm_range()" function for this, but other
architectures (arm and ia64) do the "use fake vma" thing instead, and
thus got caught up in the vma_init() changes.
At the same time, the TLB flushing code really doesn't care about most
other fields in the vma, so vma_init() is just unnecessary and
pointless.
This fixes things by having an explicit "this is just an initializer for
the TLB flush" initializer macro, which is used by the arm/arm64/ia64
people who mis-use this interface with just a dummy vma.
Fixes: 2c4541e24c55 ("mm: use vma_init() to initialize VMAs on stack and data segments")
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/arm/mach-rpc/ecard.c b/arch/arm/mach-rpc/ecard.c
index 8db62cc..04b2f22 100644
--- a/arch/arm/mach-rpc/ecard.c
+++ b/arch/arm/mach-rpc/ecard.c
@@ -212,7 +212,7 @@ static DEFINE_MUTEX(ecard_mutex);
*/
static void ecard_init_pgtables(struct mm_struct *mm)
{
- struct vm_area_struct vma;
+ struct vm_area_struct vma = TLB_FLUSH_VMA(mm, VM_EXEC);
/* We want to set up the page tables for the following mapping:
* Virtual Physical
@@ -237,9 +237,6 @@ static void ecard_init_pgtables(struct mm_struct *mm)
memcpy(dst_pgd, src_pgd, sizeof(pgd_t) * (EASI_SIZE / PGDIR_SIZE));
- vma_init(&vma, mm);
- vma.vm_flags = VM_EXEC;
-
flush_tlb_range(&vma, IO_START, IO_START + IO_SIZE);
flush_tlb_range(&vma, EASI_START, EASI_START + EASI_SIZE);
}
diff --git a/arch/arm64/include/asm/tlb.h b/arch/arm64/include/asm/tlb.h
index d87f2d6..0ad1cf2 100644
--- a/arch/arm64/include/asm/tlb.h
+++ b/arch/arm64/include/asm/tlb.h
@@ -37,9 +37,7 @@ static inline void __tlb_remove_table(void *_table)
static inline void tlb_flush(struct mmu_gather *tlb)
{
- struct vm_area_struct vma;
-
- vma_init(&vma, tlb->mm);
+ struct vm_area_struct vma = TLB_FLUSH_VMA(tlb->mm, 0);
/*
* The ASID allocator will either invalidate the ASID or mark
diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
index 1854e49..192b3ba 100644
--- a/arch/arm64/mm/hugetlbpage.c
+++ b/arch/arm64/mm/hugetlbpage.c
@@ -108,13 +108,10 @@ static pte_t get_clear_flush(struct mm_struct *mm,
unsigned long pgsize,
unsigned long ncontig)
{
- struct vm_area_struct vma;
pte_t orig_pte = huge_ptep_get(ptep);
bool valid = pte_valid(orig_pte);
unsigned long i, saddr = addr;
- vma_init(&vma, mm);
-
for (i = 0; i < ncontig; i++, addr += pgsize, ptep++) {
pte_t pte = ptep_get_and_clear(mm, addr, ptep);
@@ -127,8 +124,10 @@ static pte_t get_clear_flush(struct mm_struct *mm,
orig_pte = pte_mkdirty(orig_pte);
}
- if (valid)
+ if (valid) {
+ struct vm_area_struct vma = TLB_FLUSH_VMA(mm, 0);
flush_tlb_range(&vma, saddr, addr);
+ }
return orig_pte;
}
@@ -147,10 +146,9 @@ static void clear_flush(struct mm_struct *mm,
unsigned long pgsize,
unsigned long ncontig)
{
- struct vm_area_struct vma;
+ struct vm_area_struct vma = TLB_FLUSH_VMA(mm, 0);
unsigned long i, saddr = addr;
- vma_init(&vma, mm);
for (i = 0; i < ncontig; i++, addr += pgsize, ptep++)
pte_clear(mm, addr, ptep);
diff --git a/arch/ia64/include/asm/tlb.h b/arch/ia64/include/asm/tlb.h
index db89e73..516355a 100644
--- a/arch/ia64/include/asm/tlb.h
+++ b/arch/ia64/include/asm/tlb.h
@@ -115,12 +115,11 @@ ia64_tlb_flush_mmu_tlbonly(struct mmu_gather *tlb, unsigned long start, unsigned
flush_tlb_all();
} else {
/*
- * XXX fix me: flush_tlb_range() should take an mm pointer instead of a
- * vma pointer.
+ * flush_tlb_range() takes a vma instead of a mm pointer because
+ * some architectures want the vm_flags for ITLB/DTLB flush.
*/
- struct vm_area_struct vma;
+ struct vm_area_struct vma = TLB_FLUSH_VMA(tlb->mm, 0);
- vma_init(&vma, tlb->mm);
/* flush the address range from the tlb: */
flush_tlb_range(&vma, start, end);
/* now flush the virt. page-table area mapping the address range: */
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 7ba6d35..68a5121 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -466,6 +466,9 @@ static inline void vma_set_anonymous(struct vm_area_struct *vma)
vma->vm_ops = NULL;
}
+/* flush_tlb_range() takes a vma, not a mm, and can care about flags */
+#define TLB_FLUSH_VMA(mm,flags) { .vm_mm = (mm), .vm_flags = (flags) }
+
struct mmu_gather;
struct inode;