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[195.135.221.5]) by mx.google.com with ESMTPS id b17si1362602ejj.243.2019.02.06.21.38.37 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 06 Feb 2019 21:38:37 -0800 (PST) Received-SPF: softfail (google.com: domain of transitioning dave@stgolabs.net does not designate 195.135.221.5 as permitted sender) client-ip=195.135.221.5; Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning dave@stgolabs.net does not designate 195.135.221.5 as permitted sender) smtp.mailfrom=dave@stgolabs.net Received: from emea4-mta.ukb.novell.com ([10.120.13.87]) by smtp.nue.novell.com with ESMTP (TLS encrypted); Thu, 07 Feb 2019 06:38:36 +0100 Received: from localhost.localdomain (nwb-a10-snat.microfocus.com [10.120.13.201]) by emea4-mta.ukb.novell.com with ESMTP (TLS encrypted); Thu, 07 Feb 2019 05:38:05 +0000 From: Davidlohr Bueso To: akpm@linux-foundation.org Cc: linux-mm@kvack.org, dave@stgolabs.net, linux-kernel@vger.kernel.org, Ralf Baechle , Paul Burton , James Hogan , linux-mips@vger.kernel.org, Davidlohr Bueso Subject: [PATCH 2/2] MIPS/c-r4k: do no use mmap_sem for gup_fast() Date: Wed, 6 Feb 2019 21:37:40 -0800 Message-Id: <20190207053740.26915-3-dave@stgolabs.net> X-Mailer: git-send-email 2.16.4 In-Reply-To: <20190207053740.26915-1-dave@stgolabs.net> References: <20190207053740.26915-1-dave@stgolabs.net> X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: It is well known that because the mm can internally call the regular gup_unlocked if the lockless approach fails and take the sem there, the caller must not hold the mmap_sem already. Fixes: e523f289fe4d (MIPS: c-r4k: Fix sigtramp SMP call to use kmap) Cc: Ralf Baechle Cc: Paul Burton Cc: James Hogan Cc: linux-mips@vger.kernel.org Signed-off-by: Davidlohr Bueso --- arch/mips/mm/c-r4k.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) diff --git a/arch/mips/mm/c-r4k.c b/arch/mips/mm/c-r4k.c index cc4e17caeb26..38fe86928837 100644 --- a/arch/mips/mm/c-r4k.c +++ b/arch/mips/mm/c-r4k.c @@ -1034,11 +1034,9 @@ static void r4k_flush_cache_sigtramp(unsigned long addr) struct flush_cache_sigtramp_args args; int npages; - down_read(¤t->mm->mmap_sem); - npages = get_user_pages_fast(addr, 1, 0, &args.page); if (npages < 1) - goto out; + return; args.mm = current->mm; args.addr = addr; @@ -1046,8 +1044,6 @@ static void r4k_flush_cache_sigtramp(unsigned long addr) r4k_on_each_cpu(R4K_HIT, local_r4k_flush_cache_sigtramp, &args); put_page(args.page); -out: - up_read(¤t->mm->mmap_sem); } static void r4k_flush_icache_all(void) -- 2.16.4