linux-kernel - [PATCH] x86/tlb: Revert: Align TLB invalidation info

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Date:   Tue, 16 Apr 2019 10:03:35 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>, Borislav Petkov <bp@...en8.de>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        linux-kernel@...r.kernel.org, Andy Lutomirski <luto@...nel.org>,
        Nadav Amit <namit@...are.com>,
        Dave Hansen <dave.hansen@...el.com>
Subject: [PATCH] x86/tlb: Revert: Align TLB invalidation info


It was found 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.

Fixes: 515ab7c41306 ("x86/mm: Align TLB invalidation info")
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
Index: linux-2.6/arch/x86/mm/tlb.c
===================================================================
--- linux-2.6.orig/arch/x86/mm/tlb.c
+++ linux-2.6/arch/x86/mm/tlb.c
@@ -728,7 +728,7 @@ 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,