mm: VMA sequence count
Wrap the VMA modifications (vma_adjust/unmap_page_range) with sequence
counts such that we can easily test if a VMA is changed.
The unmap_page_range() one allows us to make assumptions about
page-tables; when we find the seqcount hasn't changed we can assume
page-tables are still valid.
The flip side is that we cannot distinguish between a vma_adjust() and
the unmap_page_range() -- where with the former we could have
re-checked the vma bounds against the address.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
[Port to 4.12 kernel]
[Build depends on CONFIG_SPECULATIVE_PAGE_FAULT]
[Introduce vm_write_* inline function depending on
CONFIG_SPECULATIVE_PAGE_FAULT]
[Fix lock dependency between mapping->i_mmap_rwsem and vma->vm_sequence by
using vm_raw_write* functions]
[Fix a lock dependency warning in mmap_region() when entering the error
path]
[move sequence initialisation INIT_VMA()]
Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Change-Id: Ibc23ef3b9dbb80323c0f24cb06da34b4c3a8fa71
Patch-mainline: linux-mm @ 17 Apr 2018 16:33:14
[vinmenon@codeaurora.org: trivial merge conflict fixes]
Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
diff --git a/mm/memory.c b/mm/memory.c
index 4fa2c30..188722e 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1285,6 +1285,7 @@
unsigned long next;
BUG_ON(addr >= end);
+ vm_write_begin(vma);
tlb_start_vma(tlb, vma);
pgd = pgd_offset(vma->vm_mm, addr);
do {
@@ -1294,6 +1295,7 @@
next = zap_pud_range(tlb, vma, pgd, addr, next, details);
} while (pgd++, addr = next, addr != end);
tlb_end_vma(tlb, vma);
+ vm_write_end(vma);
}