Messages in this thread | | | From | Yafang Shao <> | Date | Thu, 7 Oct 2021 23:47:09 +0800 | Subject | Re: [PATCH v2 3/4] sched.h: extend task comm from 16 to 24 for CONFIG_BASE_FULL |
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On Thu, Oct 7, 2021 at 10:56 PM Kees Cook <keescook@chromium.org> wrote: > > On Thu, Oct 07, 2021 at 12:07:51PM +0000, Yafang Shao wrote: > > When I was implementing a new per-cpu kthread cfs_migration, I found the > > comm of it "cfs_migration/%u" is truncated due to the limitation of > > TASK_COMM_LEN. For example, the comm of the percpu thread on CPU10~19 are > > all with the same name "cfs_migration/1", which will confuse the user. This > > issue is not critical, because we can get the corresponding CPU from the > > task's Cpus_allowed. But for kthreads correspoinding to other hardware > > devices, it is not easy to get the detailed device info from task comm, > > for example, > > > > jbd2/nvme0n1p2- > > nvidia-modeset/ > > > > We can also shorten the name to work around this problem, but I find > > there are so many truncated kthreads: > > > > rcu_tasks_kthre > > rcu_tasks_rude_ > > rcu_tasks_trace > > poll_mpt3sas0_s > > ext4-rsv-conver > > xfs-reclaim/sd{a, b, c, ...} > > xfs-blockgc/sd{a, b, c, ...} > > xfs-inodegc/sd{a, b, c, ...} > > audit_send_repl > > ecryptfs-kthrea > > vfio-irqfd-clea > > jbd2/nvme0n1p2- > > ... > > > > Besides the in-tree kthreads listed above, the out-of-tree kthreads may > > also be truncated: > > > > rtase_work_queu > > nvidia-modeset/ > > UVM global queu > > UVM deferred re > > ... > > > > We should improve this problem fundamentally. > > > > This patch extends the size of task comm to 24 bytes, which is the > > same length with workqueue's, for the CONFIG_BASE_FULL case. And for the > > CONFIG_BASE_SMALL case, the size of task comm is still kept as 16 bytes. > > > > Suggested-by: Petr Mladek <pmladek@suse.com> > > Signed-off-by: Yafang Shao <laoar.shao@gmail.com> > > This, as expected, adds 8 bytes to task_struct, which is reasonable. I > don't see any easy places to consolidate other members to make this a > "free" change, but I did just remove 64 bytes from task_struct[1], so > this is okay. :) >
Cool!
> Reviewed-by: Kees Cook <keescook@chromium.org> >
Thanks for the review.
> [1] https://lore.kernel.org/lkml/20210924025450.4138503-1-keescook@chromium.org/ >
-- Thanks Yafang
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