[PATCH 5.0 120/122] x86/mm/tlb: Revert "x86/mm: Align TLB invalidation info"

Greg Kroah-Hartman
2019-05-06T14:38:47Z

From: Peter Zijlstra <peterz@infradead.org>

commit 780e0106d468a2962b16b52fdf42898f2639e0a0 upstream.

Revert the following commit:

515ab7c41306: ("x86/mm: Align TLB invalidation info")

I found out (the hard way) that under some .config options (notably L1_CACHE_SHIFT=7)
and compiler combinations this on-stack alignment leads to a 320 byte
stack usage, which then triggers a KASAN stack warning elsewhere.

Using 320 bytes of stack space for a 40 byte structure is ludicrous and
clearly not right.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Nadav Amit <namit@vmware.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 515ab7c41306 ("x86/mm: Align TLB invalidation info")
Link: http://lkml.kernel.org/r/20190416080335.GM7905@worktop.programming.kicks-ass.net
[ Minor changelog edits. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/x86/mm/tlb.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -731,7 +731,7 @@ void flush_tlb_mm_range(struct mm_struct
{
int cpu;

- struct flush_tlb_info info __aligned(SMP_CACHE_BYTES) = {
+ struct flush_tlb_info info = {
.mm = mm,
.stride_shift = stride_shift,
.freed_tables = freed_tables,