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[109.81.92.77]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-37189896d74sm3086190f8f.68.2024.08.16.01.18.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 16 Aug 2024 01:18:54 -0700 (PDT) Date: Fri, 16 Aug 2024 10:18:53 +0200 From: Michal Hocko To: Andrew Morton Cc: Matthew Wilcox , Roman Gushchin , Shakeel Butt , Johannes Weiner , Muchun Song , "T . J . Mercier" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Meta kernel team , cgroups@vger.kernel.org Subject: Re: [PATCH v2] memcg: replace memcg ID idr with xarray Message-ID: References: <20240815155402.3630804-1-shakeel.butt@linux.dev> <20240816004334.41ce3acf52ba082399a76d88@linux-foundation.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240816004334.41ce3acf52ba082399a76d88@linux-foundation.org> On Fri 16-08-24 00:43:34, Andrew Morton wrote: > On Fri, 16 Aug 2024 09:19:58 +0200 Michal Hocko wrote: > > > On Thu 15-08-24 22:16:27, Matthew Wilcox wrote: > > > On Thu, Aug 15, 2024 at 07:31:43PM +0000, Roman Gushchin wrote: > > > > There is another subtle change here: xa_alloc() returns -EBUSY in the case > > > > of the address space exhaustion, while the old code returned -ENOSPC. > > > > It's unlikely a big practical problem. > > > > > > I decided that EBUSY was the right errno for this situation; > > > > > > #define EBUSY 16 /* Device or resource busy */ > > > #define ENOSPC 28 /* No space left on device */ > > > > > > ENOSPC seemed wrong; the device isn't out of space. > > > > The thing is that this is observable by userspace - mkdir would return a > > different and potentially unexpected errno. We can try and see whether > > anybody complains or just translate the error. > > The mkdir(2) manpage doesn't list EBUSY. Maybe ENOMEM is close enough. it used to report ENOSPC with xarray. -- Michal Hocko SUSE Labs