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[125.236.136.221]) by smtp.gmail.com with ESMTPSA id u1-20020a17090282c100b001d8f81ece98sm5071018plz.104.2024.02.04.18.32.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 04 Feb 2024 18:32:45 -0800 (PST) Received: by xplor.waratah.dyndns.org (Postfix, from userid 1000) id 2936F36027A; Mon, 5 Feb 2024 15:32:42 +1300 (NZDT) From: Michael Schmitz To: linux-m68k@vger.kernel.org Cc: geert@linux-m68k.org, uli@fpond.eu, fthain@linux-m68k.org, viro@zeniv.linux.org.uk, Michael Schmitz Subject: [PATCH RFC v2 7/8] m68k: fix livelock in uaccess Date: Mon, 5 Feb 2024 15:32:35 +1300 Message-Id: <20240205023236.9325-8-schmitzmic@gmail.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20240205023236.9325-1-schmitzmic@gmail.com> References: <20240205023236.9325-1-schmitzmic@gmail.com> Precedence: bulk X-Mailing-List: linux-m68k@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: From: Al Viro m68k equivalent of 26178ec11ef3 "x86: mm: consolidate VM_FAULT_RETRY handling" If e.g. get_user() triggers a page fault and a fatal signal is caught, we might end up with handle_mm_fault() returning VM_FAULT_RETRY and not doing anything to page tables. In such case we must *not* return to the faulting insn - that would repeat the entire thing without making any progress; what we need instead is to treat that as failed (user) memory access. MSch: v4.4 backport compile errors fixes. Tested-by: Finn Thain Tested-by: Geert Uytterhoeven Acked-by: Geert Uytterhoeven Signed-off-by: Al Viro Signed-off-by: Michael Schmitz --- arch/m68k/mm/fault.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/arch/m68k/mm/fault.c b/arch/m68k/mm/fault.c index 6a94cdd0c830..f94df64c3784 100644 --- a/arch/m68k/mm/fault.c +++ b/arch/m68k/mm/fault.c @@ -139,8 +139,11 @@ good_area: fault = handle_mm_fault(mm, vma, address, flags); pr_debug("handle_mm_fault returns %d\n", fault); - if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) + if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) { + if (!user_mode(regs)) + goto no_context; return 0; + } if (unlikely(fault & VM_FAULT_ERROR)) { if (fault & VM_FAULT_OOM) -- 2.17.1