linux-kernel - [PATCH 1/1] MIPS: Fix fpu trap invoked by io-worker

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Message-Id: <c3a171e31fab6eaaadd67b8e672c5d33aa9ee20c.1631510421.git.yangbonis@icloud.com>
Date:   Mon, 13 Sep 2021 13:37:17 +0800
From:   wangyangbo <yangbonis@...oud.com>
To:     tsbogend@...ha.franken.de, hejinyang@...ngson.cn,
        chenhuacai@...nel.org, peterz@...radead.org, frederic@...nel.org,
        axboe@...nel.dk
Cc:     linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org,
        xiehuanjun@...ontech.com, wangyangbo <yangbonis@...oud.com>
Subject: [PATCH 1/1] MIPS: Fix fpu trap invoked by io-worker

From: wangyangbo <wangyangbo@...ontech.com>

Create worker thread from original user task in mips, possibly copying
FPU flag from user task, introducing save_fp when switch_to, triggering
do_cpu trap. So clear USEDFPU flag for IO_WORKER in copy_thread.

Signed-off-by: wangyangbo <yangbonis@...oud.com>
---
 arch/mips/kernel/process.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/mips/kernel/process.c b/arch/mips/kernel/process.c
index 95aa86fa6077..0095006d48c7 100644
--- a/arch/mips/kernel/process.c
+++ b/arch/mips/kernel/process.c
@@ -135,6 +135,9 @@ int copy_thread(unsigned long clone_flags, unsigned long usp,
 		status |= ST0_EXL;
 #endif
 		childregs->cp0_status = status;
+
+		if (p->flags & PF_IO_WORKER)
+			clear_tsk_thread_flag(p, TIF_USEDFPU);
 		return 0;
 	}
 
-- 
2.20.1