From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: [patch 057/128] mm/gup.c: further document vma_permits_fault() Date: Mon, 01 Jun 2020 21:48:33 -0700 Message-ID: <20200602044833.p9kfndHEN%akpm@linux-foundation.org> References: <20200601214457.919c35648e96a2b46b573fe1@linux-foundation.org> Reply-To: linux-kernel@vger.kernel.org Return-path: Received: from mail.kernel.org ([198.145.29.99]:39752 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725872AbgFBEse (ORCPT ); Tue, 2 Jun 2020 00:48:34 -0400 In-Reply-To: <20200601214457.919c35648e96a2b46b573fe1@linux-foundation.org> Sender: mm-commits-owner@vger.kernel.org List-Id: mm-commits@vger.kernel.org To: akpm@linux-foundation.org, linux-mm@kvack.org, miles.chen@mediatek.com, mm-commits@vger.kernel.org, torvalds@linux-foundation.org From: Miles Chen Subject: mm/gup.c: further document vma_permits_fault() Describe the caller's responsibilities when passing FAULT_FLAG_ALLOW_RETRY. Link: http://lkml.kernel.org/r/1586915606.5647.5.camel@mtkswgap22 Signed-off-by: Andrew Morton --- mm/gup.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/mm/gup.c~mm-gupc-further-document-vma_permits_fault +++ a/mm/gup.c @@ -1176,7 +1176,8 @@ static bool vma_permits_fault(struct vm_ * @address: user address * @fault_flags:flags to pass down to handle_mm_fault() * @unlocked: did we unlock the mmap_sem while retrying, maybe NULL if caller - * does not allow retry + * does not allow retry. If NULL, the caller must guarantee + * that fault_flags does not contain FAULT_FLAG_ALLOW_RETRY. * * This is meant to be called in the specific scenario where for locking reasons * we try to access user memory in atomic context (within a pagefault_disable() _