On Thu, Oct 21, 2021 at 08:52:22PM -0700, Andrew Morton wrote: > On Thu, 21 Oct 2021 03:45:07 +0000 Yafang Shao <laoar.shao@xxxxxxxxx> wrote: > > > This patchset changes files among many subsystems. I don't know which > > tree it should be applied to, so I just base it on Linus's tree. > > I can do that ;) > > > There're many truncated kthreads in the kernel, which may make trouble > > for the user, for example, the user can't get detailed device > > information from the task comm. > > That sucked of us. > > > This patchset tries to improve this problem fundamentally by extending > > the task comm size from 16 to 24. In order to do that, we have to do > > some cleanups first. > > It's at v5 and there's no evidence of review activity? C'mon, folks! It's on my list! :) It's a pretty subtle area that rarely changes, so I want to make sure I'm a full coffee to do the review. :) > > 1. Make the copy of task comm always safe no matter what the task > > comm size is. For example, > > > > Unsafe Safe > > strlcpy strscpy_pad > > strncpy strscpy_pad > > bpf_probe_read_kernel bpf_probe_read_kernel_str > > bpf_core_read_str > > bpf_get_current_comm > > perf_event__prepare_comm > > prctl(2) > > > > 2. Replace the old hard-coded 16 with a new macro TASK_COMM_LEN_16 to > > make it more grepable. > > > > 3. Extend the task comm size to 24 for CONFIG_BASE_FULL case and keep it > > as 16 for CONFIG_BASE_SMALL. > > Is this justified? How much simpler/more reliable/more maintainable/ > would the code be if we were to make CONFIG_BASE_SMALL suffer with the > extra 8 bytes? Does anyone "own" CONFIG_BASE_SMALL? Gonna go with "no": $ git ann init/Kconfig| grep 'config BASE_SMALL' 1da177e4c3f41 (Linus Torvalds 2005-04-16 15:20:36 -0700 2054)config BASE_SMALL And it looks mostly unused: $ git grep CONFIG_BASE_SMALL | cut -d: -f1 | sort -u | xargs -n1 git ann -f | grep 'CONFIG_BASE_SMALL' b2af018ff26f1 (Ingo Molnar 2009-01-28 17:36:56 +0100 18)#if CONFIG_BASE_SMALL == 0 fcdba07ee390d ( Jiri Olsa 2011-02-07 19:31:25 +0100 54)#define CON_BUF_SIZE (CONFIG_BASE_SMALL ? 256 : PAGE_SIZE) Blaming lines: 100% (46/46), done. 1da177e4c3f41 (Linus Torvalds 2005-04-16 15:20:36 -0700 28)#define PID_MAX_DEFAULT (CONFIG_BASE_SMALL ? 0x1000 : 0x8000) 1da177e4c3f41 (Linus Torvalds 2005-04-16 15:20:36 -0700 34)#define PID_MAX_LIMIT (CONFIG_BASE_SMALL ? PAGE_SIZE * 8 : \ Blaming lines: 100% (162/162), done. f86dcc5aa8c79 (Eric Dumazet 2009-10-07 00:37:59 +0000 31)#define UDP_HTABLE_SIZE_MIN (CONFIG_BASE_SMALL ? 128 : 256) 02c02bf12c5d8 (Matthew Wilcox 2017-11-03 23:09:45 -0400 1110)#define XA_CHUNK_SHIFT (CONFIG_BASE_SMALL ? 4 : 6) a52b89ebb6d44 (Davidlohr Bueso 2014-01-12 15:31:23 -0800 4249)#if CONFIG_BASE_SMALL 7b44ab978b77a (Eric W. Biederman 2011-11-16 23:20:58 -0800 78)#define UIDHASH_BITS (CONFIG_BASE_SMALL ? 3 : 7) -- Kees Cook
