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[198.145.29.99]) by mx.google.com with ESMTPS id u9si32906083pgf.198.2019.08.06.14.33.32 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 06 Aug 2019 14:33:33 -0700 (PDT) Received-SPF: pass (google.com: domain of sashal@kernel.org designates 198.145.29.99 as permitted sender) client-ip=198.145.29.99; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=IO2DxLoL; spf=pass (google.com: domain of sashal@kernel.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=sashal@kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id C973A21743; Tue, 6 Aug 2019 21:33:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1565127212; bh=TN/yZ7FjGl5BN0jJpt8bZnFuEvxtK5gvDFA4qWawSi8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=IO2DxLoLP2XBTcG6DKhj+LtbEryyetM83hLNmJuHMzuRKI1DKItYI61T3Y9eWyOTY /WdZgZ1Jo2dpipEoIzfC557ZT7OgPUEwDvZfoguzUH6oEDsrLLk91pDrEHNz1nronB shkGE3xB2I3bz6k9TSoERWwkMIU5rIxQeJSWY5CM= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Christoph Hellwig , Ralph Campbell , Jason Gunthorpe , Felix Kuehling , Sasha Levin , linux-mm@kvack.org, linux-doc@vger.kernel.org Subject: [PATCH AUTOSEL 5.2 10/59] mm/hmm: always return EBUSY for invalid ranges in hmm_range_{fault,snapshot} Date: Tue, 6 Aug 2019 17:32:30 -0400 Message-Id: <20190806213319.19203-10-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190806213319.19203-1-sashal@kernel.org> References: <20190806213319.19203-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit 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: From: Christoph Hellwig [ Upstream commit 2bcbeaefde2f0384d6ad351c151b1a9fe7791a0a ] We should not have two different error codes for the same condition. EAGAIN must be reserved for the FAULT_FLAG_ALLOW_RETRY retry case and signals to the caller that the mmap_sem has been unlocked. Use EBUSY for the !valid case so that callers can get the locking right. Link: https://lore.kernel.org/r/20190724065258.16603-2-hch@lst.de Tested-by: Ralph Campbell Signed-off-by: Christoph Hellwig Reviewed-by: Ralph Campbell Reviewed-by: Jason Gunthorpe Reviewed-by: Felix Kuehling [jgg: elaborated commit message] Signed-off-by: Jason Gunthorpe Signed-off-by: Sasha Levin --- Documentation/vm/hmm.rst | 2 +- mm/hmm.c | 10 ++++------ 2 files changed, 5 insertions(+), 7 deletions(-) diff --git a/Documentation/vm/hmm.rst b/Documentation/vm/hmm.rst index 7cdf7282e0229..65b6c1109cc81 100644 --- a/Documentation/vm/hmm.rst +++ b/Documentation/vm/hmm.rst @@ -231,7 +231,7 @@ respect in order to keep things properly synchronized. The usage pattern is:: ret = hmm_range_snapshot(&range); if (ret) { up_read(&mm->mmap_sem); - if (ret == -EAGAIN) { + if (ret == -EBUSY) { /* * No need to check hmm_range_wait_until_valid() return value * on retry we will get proper error with hmm_range_snapshot() diff --git a/mm/hmm.c b/mm/hmm.c index 4c405dfbd2b3d..27dd9a8816272 100644 --- a/mm/hmm.c +++ b/mm/hmm.c @@ -995,7 +995,7 @@ EXPORT_SYMBOL(hmm_range_unregister); * @range: range * Returns: -EINVAL if invalid argument, -ENOMEM out of memory, -EPERM invalid * permission (for instance asking for write and range is read only), - * -EAGAIN if you need to retry, -EFAULT invalid (ie either no valid + * -EBUSY if you need to retry, -EFAULT invalid (ie either no valid * vma or it is illegal to access that range), number of valid pages * in range->pfns[] (from range start address). * @@ -1019,7 +1019,7 @@ long hmm_range_snapshot(struct hmm_range *range) do { /* If range is no longer valid force retry. */ if (!range->valid) - return -EAGAIN; + return -EBUSY; vma = find_vma(hmm->mm, start); if (vma == NULL || (vma->vm_flags & device_vma)) @@ -1117,10 +1117,8 @@ long hmm_range_fault(struct hmm_range *range, bool block) do { /* If range is no longer valid force retry. */ - if (!range->valid) { - up_read(&hmm->mm->mmap_sem); - return -EAGAIN; - } + if (!range->valid) + return -EBUSY; vma = find_vma(hmm->mm, start); if (vma == NULL || (vma->vm_flags & device_vma)) -- 2.20.1