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[2607:7c80:54:e::133]) by mx.google.com with ESMTPS id h189si1623841pge.378.2019.04.18.04.18.46 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 18 Apr 2019 04:18:46 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of willy@infradead.org designates 2607:7c80:54:e::133 as permitted sender) client-ip=2607:7c80:54:e::133; Authentication-Results: mx.google.com; dkim=pass header.i=@infradead.org header.s=bombadil.20170209 header.b=SGzmY92g; spf=pass (google.com: best guess record for domain of willy@infradead.org designates 2607:7c80:54:e::133 as permitted sender) smtp.mailfrom=willy@infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=MTWvlBGcxn9p8FR3xNRCHkLm1a2gvjsLaACCdCKLnec=; b=SGzmY92ghxsMhmzlBuin913fI /+o5g6YsxrK7Fp5r8fX/4EJ0GcGp9GrtntToMJbYLeqW3dZJDBXvhJ0ItboRp5ZLFTvnXdoN+crY/ gz6AU6iXTqUPJstsFJHxGKv4W4BXHZw9pRE+jd6u6kdmg2QDE3U27rHMrC7vxB8t26Zc3ZiIDiEh1 JgBIvTy1kdkGg0J6VLNDitmFJ6VdDPpIvJH98ytffJbwqg7DU+09yemWAOU4eQuikT8XkxSe09/TY 6+sYhftp+jG99z8NJZQGfvgm4InbKAnYJtpNdqQoxXK2nqjnkCBasoMyOW3Pq53OwOclJdu/jPeBj okUu0Y0tQ==; Received: from willy by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1hH53r-00027y-4L; Thu, 18 Apr 2019 11:18:35 +0000 Date: Thu, 18 Apr 2019 04:18:34 -0700 From: Matthew Wilcox To: Andrew Morton Cc: Roman Gushchin , linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-team@fb.com, Johannes Weiner , Vlastimil Babka , Roman Gushchin , Christoph Hellwig , Joel Fernandes Subject: Re: [PATCH v4 1/2] mm: refactor __vunmap() to avoid duplicated call to find_vm_area() Message-ID: <20190418111834.GE7751@bombadil.infradead.org> References: <20190417194002.12369-1-guro@fb.com> <20190417194002.12369-2-guro@fb.com> <20190417145827.8b1c83bf22de8ba514f157e3@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190417145827.8b1c83bf22de8ba514f157e3@linux-foundation.org> User-Agent: Mutt/1.9.2 (2017-12-15) 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: On Wed, Apr 17, 2019 at 02:58:27PM -0700, Andrew Morton wrote: > On Wed, 17 Apr 2019 12:40:01 -0700 Roman Gushchin wrote: > > +static struct vm_struct *__remove_vm_area(struct vmap_area *va) > > +{ > > + struct vm_struct *vm = va->vm; > > + > > + might_sleep(); > > Where might __remove_vm_area() sleep? > > >From a quick scan I'm only seeing vfree(), and that has the > might_sleep_if(!in_interrupt()). > > So perhaps we can remove this... See commit 5803ed292e63 ("mm: mark all calls into the vmalloc subsystem as potentially sleeping") It looks like the intent is to unconditionally check might_sleep() at the entry points to the vmalloc code, rather than only catch them in the occasional place where it happens to go wrong.