linux-kernel - [tip:x86/urgent] x86/mm/tlb: Revert "x86/mm: Align TLB invalidation info"

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Message-ID: <tip-780e0106d468a2962b16b52fdf42898f2639e0a0@git.kernel.org>
Date:   Tue, 16 Apr 2019 01:13:51 -0700
From:   tip-bot for Peter Zijlstra <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     tglx@...utronix.de, peterz@...radead.org, luto@...nel.org,
        mingo@...nel.org, dave.hansen@...el.com,
        linux-kernel@...r.kernel.org, hpa@...or.com,
        torvalds@...ux-foundation.org, namit@...are.com, bp@...en8.de
Subject: [tip:x86/urgent] x86/mm/tlb: Revert "x86/mm: Align TLB invalidation
 info"

Commit-ID:  780e0106d468a2962b16b52fdf42898f2639e0a0
Gitweb:     https://git.kernel.org/tip/780e0106d468a2962b16b52fdf42898f2639e0a0
Author:     Peter Zijlstra <peterz@...radead.org>
AuthorDate: Tue, 16 Apr 2019 10:03:35 +0200
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Tue, 16 Apr 2019 10:10:13 +0200

x86/mm/tlb: Revert "x86/mm: Align TLB invalidation info"

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

diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index bc4bc7b2f075..487b8474c01c 100644
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -728,7 +728,7 @@ void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,
 {
 	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,