On Sun, Nov 19, 2017 at 10:00:39AM +0100, Michael Kerrisk (man-pages) wrote: > Hello Christian, > > > On 11/19/2017 02:25 AM, Christian Brauner wrote: > > This patch documents the following commit: > > > > commit 6397fac4915ab3002dc15aae751455da1a852f25 > > Author: Christian Brauner <christian.brauner@xxxxxxxxxx> > > Date: Wed Oct 25 00:04:41 2017 +0200 > > > > userns: bump idmap limits to 340 > > > > 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) limit on > > the number of lines in the file." since the 340 line limit is well-explained 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 = 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 implementation > > detail to users in the man page. So only mention this in the commit message. > > Furthermore, the comment about the page size restriction is misleading. The > > kernel sources show that >= page size is considered an error. > > 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
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