Commit-ID: 31e67340cc65edfd9dac5ef26f81de8414ce5906
Gitweb: https://git.kernel.org/tip/31e67340cc65edfd9dac5ef26f81de8414ce5906
Author: Rick Edgecombe <rick.p.edgecombe@xxxxxxxxx>
AuthorDate: Mon, 27 May 2019 14:10:58 -0700
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Mon, 3 Jun 2019 11:47:25 +0200
mm/vmalloc: Avoid rare case of flushing TLB with weird arguments
In a rare case, flush_tlb_kernel_range() could be called with a start
higher than the end.
In vm_remove_mappings(), in case page_address() returns 0 for all pages
(for example they were all in highmem), _vm_unmap_aliases() will be
called with start = ULONG_MAX, end = 0 and flush = 1.
If at the same time, the vmalloc purge operation is triggered by something
else while the current operation is between remove_vm_area() and
_vm_unmap_aliases(), then the vm mapping just removed will be already
purged. In this case the call of vm_unmap_aliases() may not find any other
mappings to flush and so end up flushing start = ULONG_MAX, end = 0. So
only set flush = true if we find something in the direct mapping that we
need to flush, and this way this can't happen.
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@xxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
Cc: David S. Miller <davem@xxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Meelis Roos <mroos@xxxxxxxx>
Cc: Nadav Amit <namit@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Fixes: 868b104d7379 ("mm/vmalloc: Add flag for freeing of special permsissions")
Link: https://lkml.kernel.org/r/20190527211058.2729-3-rick.p.edgecombe@xxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
mm/vmalloc.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 93b2dca2aadb..4c9e150e5ad3 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -2125,6 +2125,7 @@ static void vm_remove_mappings(struct vm_struct *area, int deallocate_pages)
{
unsigned long start = ULONG_MAX, end = 0;
int flush_reset = area->flags & VM_FLUSH_RESET_PERMS;
+ int flush_dmap = 0;
int i;
/*
@@ -2163,6 +2164,7 @@ static void vm_remove_mappings(struct vm_struct *area, int deallocate_pages)
if (addr) {
start = min(addr, start);
end = max(addr + PAGE_SIZE, end);
+ flush_dmap = 1;
}
}
@@ -2172,7 +2174,7 @@ static void vm_remove_mappings(struct vm_struct *area, int deallocate_pages)
* reset the direct map permissions to the default.
*/
set_area_direct_map(area, set_direct_map_invalid_noflush);
- _vm_unmap_aliases(start, end, 1);
+ _vm_unmap_aliases(start, end, flush_dmap);
set_area_direct_map(area, set_direct_map_default_noflush);
}
|