From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 21 Nov 2008 14:50:43 -0800 From: Andrew Morton Subject: Re: Make the get_user_pages interruptible Message-Id: <20081121145043.0e4b2bf9.akpm@linux-foundation.org> In-Reply-To: <604427e00811201403k26e4bf93tdb2dee9506756a82@mail.gmail.com> References: <604427e00811201403k26e4bf93tdb2dee9506756a82@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Ying Han Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, menage@google.com, rientjes@google.com, rohitseth@google.com List-ID: On Thu, 20 Nov 2008 14:03:36 -0800 Ying Han wrote: > make get_user_pages interruptible > The initial implementation of checking TIF_MEMDIE covers the cases of OOM > killing. If the process has been OOM killed, the TIF_MEMDIE is set and it > return immediately. This patch includes: > > 1. add the case that the SIGKILL is sent by user processes. The process can > try to get_user_pages() unlimited memory even if a user process has sent a > SIGKILL to it(maybe a monitor find the process exceed its memory limit and > try to kill it). In the old implementation, the SIGKILL won't be handled > until the get_user_pages() returns. > > 2. change the return value to be ERESTARTSYS. It makes no sense to return > ENOMEM if the get_user_pages returned by getting a SIGKILL signal. > Considering the general convention for a system call interrupted by a > signal is ERESTARTNOSYS, so the current return value is consistant to that. > > Signed-off-by: Paul Menage > Ying Han > > This isn't right? > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -1218,12 +1218,11 @@ int __get_user_pages(struct task_struct *tsk, struct m > struct page *page; > > /* > - * If tsk is ooming, cut off its access to large memory > - * allocations. It has a pending SIGKILL, but it can't > - * be processed until returning to user space. > + * If we have a pending SIGKILL, don't keep > + * allocating memory. > */ > - if (unlikely(test_tsk_thread_flag(tsk, TIF_MEMDIE))) > - return i ? i : -ENOMEM; > + if (sigkill_pending(current)) > + return -ERESTARTSYS; > > if (write) > foll_flags |= FOLL_WRITE; If this function has already put some page*'s into *pages, they will be leaked. The function fails to release those pages and it does not provide sufficient information to callers to allow them to release the pages. I thought I already mentioned that last time I saw this patch? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org