From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Wilcox Subject: Re: [PATCH 0/6] Overhaul memalloc_no* Date: Thu, 25 Jun 2020 21:34:42 +0100 Message-ID: <20200625203442.GG7703@casper.infradead.org> References: <20200625113122.7540-1-willy@infradead.org> <20200625184832.GP7606@magnolia> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20200625184832.GP7606@magnolia> Sender: linux-kernel-owner@vger.kernel.org To: "Darrick J. Wong" Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-xfs@vger.kernel.org, dm-devel@redhat.com, Mikulas Patocka , Jens Axboe , NeilBrown , Yafang Shao List-Id: dm-devel.ids On Thu, Jun 25, 2020 at 11:48:32AM -0700, Darrick J. Wong wrote: > On Thu, Jun 25, 2020 at 12:31:16PM +0100, Matthew Wilcox (Oracle) wrote: > > I want a memalloc_nowait like we have memalloc_noio and memalloc_nofs > > for an upcoming patch series, and Jens also wants it for non-blocking > > io_uring. It turns out we already have dm-bufio which could benefit > > from memalloc_nowait, so it may as well go into the tree now. > > > > The biggest problem is that we're basically out of PF_ flags, so we need > > to find somewhere else to store the PF_MEMALLOC_NOWAIT flag. It turns > > out the PF_ flags are really supposed to be used for flags which are > > accessed from other tasks, and the MEMALLOC flags are only going to > > be used by this task. So shuffling everything around frees up some PF > > flags and generally makes the world a better place. > > So, uh, how does this intersect with the patch "xfs: reintroduce > PF_FSTRANS for transaction reservation recursion protection" that > re-adds PF_TRANS because uh I guess we lost some subtlety or another at > some point? I don't know. I read that thread, but I couldn't follow the argument.