From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christian Brauner Subject: Re: [PATCH] user_namespaces.7: Record new 340 line idmap limit Date: Sun, 19 Nov 2017 10:48:44 +0100 Message-ID: <20171119094843.axqozve4trhbdvug@gmail.com> References: <20171119012505.1925-1-christian.brauner@ubuntu.com> <0b3acf79-dd24-5845-b4f4-6d2f9222a5a6@gmail.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="omt6r5hzorz6soif" Return-path: Content-Disposition: inline In-Reply-To: <0b3acf79-dd24-5845-b4f4-6d2f9222a5a6-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> Sender: linux-man-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: "Michael Kerrisk (man-pages)" Cc: Christian Brauner , containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, linux-man-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, serge-A9i7LUbDfNHQT0dZR+AlfA@public.gmane.org, ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org List-Id: linux-man@vger.kernel.org --omt6r5hzorz6soif Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sun, Nov 19, 2017 at 10:00:39AM +0100, Michael Kerrisk (man-pages) wrote: > Hello Christian, >=20 >=20 > On 11/19/2017 02:25 AM, Christian Brauner wrote: > > This patch documents the following commit: > >=20 > > commit 6397fac4915ab3002dc15aae751455da1a852f25 > > Author: Christian Brauner > > Date: Wed Oct 25 00:04:41 2017 +0200 > >=20 > > userns: bump idmap limits to 340 > >=20 > > Since Linux 4.15 the number of idmap lines has been bumped to 340. > > The patch also removes the "(arbitrary)" in "There is an (arbitrary) li= mit on > > the number of lines in the file." since the 340 line limit is well-expl= ained by > > the current implementation. The struct recording the idmaps is 12 bytes= and > > quite some proc files only allow writes the size of a single page size = which is > > 4096kB. This leaves room for 340 idmappings (340 * 12 =3D 4080 bytes). > > The struct layout itself has been chosen very carefully to allow for an > > implementation that limits the time-complexity for the idmap codepaths = to > > O(log n). However, I think it's unnecessary to expose this much impleme= ntation > > detail to users in the man page. So only mention this in the commit mes= sage. > > Furthermore, the comment about the page size restriction is misleading.= The > > kernel sources show that >=3D page size is considered an error. >=20 > Thanks for the patch and the detailed commit message. > I've applied the patch, but restored the historical details, > since users need also to now about older kernel behavior. Thanks Michael! Christian --omt6r5hzorz6soif Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIcBAABCgAGBQJaEVN6AAoJEHs8OR7+qTYkkUcP/3jDPLBjl6D9K9nBL4BvVDdf Mnhxl1BF8vEdgqOD73//fzFrbdq+jSoMGu2VzD5KLY2qT/betklxe479tmnktZkx FU9EJhCwZzeL0Tyc7w3HQgcjfHYHL871v1Gn3PEqtndtjeyieFkKXi4M8gPtz5oL 8OfArrjEFmEfC/uXXq3appK/BehROyoZTpgi6fDB1rjWGcy2rjIztYj9RsfO9mn8 wdb82nNl7tiS39xf9rqgTwKzvmyt1skeGc4L3uDWU8zED3XbxrKyt1FweDyX88Sf 0siZRO97skiahhfKerCJEezAk/wTccNJr2h95ktdS3WaJbDJbFOyXHJwdBTLNfoB /X9oyeYFKqnH6wIKYBNdY3L987qYgxU3HDk2KBBI6b+lY/oUCydNvrwIjPsIO1hM zJo3G0ID0wiaw1duDTyFp2s//t/x7LlvdDjbYDeSneYWCn+rqA4CV3jPjg0f6ngU 5mEYOhWXqwvmijc2xx8s69Ax3m501H6I3nvILToRI26LcjrYRafx4UQxpZG/7Gpx AYEJJwM9tOoX4S0R1v9lUneiPzw9Tl6dKtFc66bUShfistmze3nHnbUIjBkgaE9k Q397VpId9HynXxkxq4LhDJkpDgwmbybtO+oBF/G3x3ypzecaJ+0g/iHPpiL+ux1h cy2JKkuzSR8exnVbCOmt =MtvO -----END PGP SIGNATURE----- --omt6r5hzorz6soif-- -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html