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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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240816004334.41ce3acf52ba082399a76d88@linux-foundation.org> X-Rspam-User: X-Stat-Signature: 7idmuk9gdwkfbnuajfph8wyifn19w6w1 X-Rspamd-Queue-Id: EDD7E120009 X-Rspamd-Server: rspam11 X-HE-Tag: 1723796335-861053 X-HE-Meta: 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 KFXOQnIr ci/J6vKiWyTGFkdDF5I5kTaYky7nwoFp8BPwkevpqLtAEq1TO1nBzxs4yZf5gsjxRtB3BY5sy7P2N4i3MvZfsghLe8Fey0j68QwSFTkKaXhYuW0BRKQK8yQoT2zkhnU+jeXpvRpz/dXYYY6VC5lGR0v2HtqGEq7UX8fAaH4yFEFa91MvCDDEwXPdYnv42kQ4tqMf4fFsuXqr/GTz/ecQ0VBdIplsWeyn1IpCU0I7PReTeenhZyGF2v2DuVHYlVEqboX7/4qEggPMrOwWa5HIHOHg396kJDpPc2HPq0t/A3gGKyNrCkgmYme8srG2VFw0XejN434dE0AN4KbaQEjkBTpFHew== 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 16-08-24 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