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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: <20240816004334.41ce3acf52ba082399a76d88@linux-foundation.org> In-Reply-To: References: <20240815155402.3630804-1-shakeel.butt@linux.dev> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: B0832A0025 X-Stat-Signature: rq3a9891bboaba7xb3s86ayew3dkqex1 X-Rspam-User: X-HE-Tag: 1723794216-999905 X-HE-Meta: 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 c8+TInAa VJ1TSOZRCjEqr/IH6Fgw6OFBVJVzdOkNV+vMlovcHQfC/ZtMjyTldLey/zbd2ahE4oZ5q1RfthE5tE+2C9CZApSOZ+JbKGpsx8lbcG/szqVGm2jMbFN3p43FLkhy3JUq1V9EcmCUTAvqQAt4ha05XwNenFfPEZDBQQVKNEpfkEFHKWJsFw1t7pRpxgnl6dcufxRzMsLW1tZLJXm+C0LLJcji3VCDVK/asQemzGD35LSmvsbTCQYjTRPHiuJWFDM6MgS+0LZVF4QuEtQo2aIValpKagvvwQ/cP/lsG 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: List-Subscribe: List-Unsubscribe: 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.