linux-kernel - [PATCH 4.19 97/99] x86/mm/tlb: Revert "x86/mm: Align TLB invalidation info"

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Date:   Mon,  6 May 2019 16:33:10 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Nadav Amit <namit@...are.com>,
        Andy Lutomirski <luto@...nel.org>,
        Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>
Subject: [PATCH 4.19 97/99] x86/mm/tlb: Revert "x86/mm: Align TLB invalidation info"

From: Peter Zijlstra <peterz@...radead.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@...radead.org>
Acked-by: Linus Torvalds <torvalds@...ux-foundation.org>
Acked-by: Nadav Amit <namit@...are.com>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Dave Hansen <dave.hansen@...el.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.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@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.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
@@ -694,7 +694,7 @@ 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,
 	};