Changes since v4: ================ - v4 can be seen here: https://lore.kernel.org/lkml/20250507110444.963779-1-bhupesh@xxxxxxxxxx/ - As suggested by Kees, replaced tsk->comm with tsk->comm_str, inside 'task_struct' where TASK_COMM_EXT_LEN is 64-bytes. Changes since v3: ================ - v3 can be seen here: https://lore.kernel.org/lkml/20250507110444.963779-1-bhupesh@xxxxxxxxxx/ - As suggested by Petr and Steven, used 'comm_ext' name instead of 'real_comm'. Correspondingly the macro name is changed to 'TASK_COMM_EXT_LEN' for the 64-byte extended comm. - Rebased this patchset on linux-next/master, which contain the following patch from Steven now: 155fd6c3e2f0 ("tracing/sched: Use __string() instead of fixed lengths for task->comm") - Accordingly, v4 drops the changes done for 'trace/sched' events in v3, but retains the 'safe' memcpy' changes for other kernel trace users. Changes since v2: ================ - v2 can be seen here: https://lore.kernel.org/lkml/20250331121820.455916-1-bhupesh@xxxxxxxxxx/ - As suggested by Yafang and Kees, picked Linus' suggested approach for this version (see: <https://lore.kernel.org/all/CAHk-=wjAmmHUg6vho1KjzQi2=psR30+CogFd4aXrThr2gsiS4g@xxxxxxxxxxxxxx/>). - Dropped kthreads patch from this version. It would be sent out separately, if we have a consensus on this approach. Changes since v1: ================ - v1 can be seen here: https://lore.kernel.org/lkml/20250314052715.610377-1-bhupesh@xxxxxxxxxx/ - As suggested by Kees, added [PATCH 3/3] to have a consistent 'full_name' entry inside 'task_struct' which both tasks and kthreads can use. - Fixed the commit message to indicate that the existing ABI '/proc/$pid/task/$tid/comm' remains untouched and a parallel '/proc/$pid/task/$tid/full_name' ABI for new (interested) users. While working with user-space debugging tools which work especially on linux gaming platforms, I found that the task name is truncated due to the limitation of TASK_COMM_LEN. Now, during debug tracing, seeing truncated names is not very useful, especially on gaming platforms where the number of tasks running can be very high. This patchset does not touch 'TASK_COMM_LEN' at all, i.e. 'TASK_COMM_LEN' and the 16-byte design remains untouched. Via this patchset, as Kees suggested 'tsk->comm' is replaced with 'tsk->comm_str', inside 'task_struct': union { char comm_str[TASK_COMM_EXT_LEN]; }; where TASK_COMM_EXT_LEN is 64-bytes. And then 'get_task_comm()' to pass 'tsk->comm_str' to the existing users. This would mean that ABI is maintained while ensuring that: - Existing users of 'get_task_comm'/ 'set_task_comm' will get 'tsk->comm_str' truncated to a maximum of 'TASK_COMM_LEN' (16-bytes) to maintain ABI, - New / Modified users of 'get_task_comm'/ 'set_task_comm' will get 'tsk->comm_str' supported for a maximum of 'TASK_COMM_EXTLEN' (64-bytes). Note, that the existing users have not been modified to migrate to 'TASK_COMM_EXT_LEN', in case they have hard-coded expectations of dealing with only a 'TASK_COMM_LEN' long 'tsk->comm_str'. After this change, gdb is able to show full name of the task, using a simple app which generates threads with long names [see 1]: # gdb ./threadnames -ex "run info thread" -ex "detach" -ex "quit" > log # cat log NameThatIsTooLongForComm[4662] [1]. https://github.com/lostgoat/tasknames Bhupesh (3): exec: Remove obsolete comments treewide: Switch memcpy() users of 'task->comm' to a more safer implementation treewide: Switch from tsk->comm to tsk->comm_str which is 64 bytes long arch/arm64/kernel/traps.c | 2 +- arch/arm64/kvm/mmu.c | 2 +- block/blk-core.c | 2 +- block/bsg.c | 2 +- drivers/char/random.c | 2 +- drivers/hid/hid-core.c | 6 +++--- drivers/mmc/host/tmio_mmc_core.c | 6 +++--- drivers/pci/pci-sysfs.c | 2 +- drivers/scsi/scsi_ioctl.c | 2 +- drivers/tty/serial/serial_core.c | 2 +- drivers/tty/tty_io.c | 8 ++++---- drivers/usb/core/devio.c | 16 ++++++++-------- drivers/usb/core/message.c | 2 +- drivers/vfio/group.c | 2 +- drivers/vfio/vfio_iommu_type1.c | 2 +- drivers/vfio/vfio_main.c | 2 +- drivers/xen/evtchn.c | 2 +- drivers/xen/grant-table.c | 2 +- fs/binfmt_elf.c | 2 +- fs/coredump.c | 4 ++-- fs/drop_caches.c | 2 +- fs/exec.c | 8 ++++---- fs/ext4/dir.c | 2 +- fs/ext4/inode.c | 2 +- fs/ext4/namei.c | 2 +- fs/ext4/super.c | 12 ++++++------ fs/hugetlbfs/inode.c | 2 +- fs/ioctl.c | 2 +- fs/iomap/direct-io.c | 2 +- fs/jbd2/transaction.c | 2 +- fs/locks.c | 2 +- fs/netfs/internal.h | 2 +- fs/proc/base.c | 2 +- fs/read_write.c | 2 +- fs/splice.c | 2 +- include/linux/coredump.h | 3 ++- include/linux/filter.h | 2 +- include/linux/ratelimit.h | 2 +- include/linux/sched.h | 17 ++++++++++------- include/trace/events/block.h | 5 +++++ include/trace/events/oom.h | 1 + include/trace/events/osnoise.h | 1 + include/trace/events/signal.h | 1 + include/trace/events/task.h | 2 ++ init/init_task.c | 2 +- ipc/sem.c | 2 +- kernel/acct.c | 2 +- kernel/audit.c | 4 ++-- kernel/auditsc.c | 10 +++++----- kernel/bpf/helpers.c | 2 +- kernel/capability.c | 4 ++-- kernel/cgroup/cgroup-v1.c | 2 +- kernel/cred.c | 4 ++-- kernel/events/core.c | 2 +- kernel/exit.c | 6 +++--- kernel/fork.c | 9 +++++++-- kernel/freezer.c | 4 ++-- kernel/futex/waitwake.c | 2 +- kernel/hung_task.c | 10 +++++----- kernel/irq/manage.c | 2 +- kernel/kthread.c | 2 +- kernel/locking/rtmutex.c | 2 +- kernel/printk/printk.c | 2 +- kernel/sched/core.c | 22 +++++++++++----------- kernel/sched/debug.c | 4 ++-- kernel/signal.c | 6 +++--- kernel/sys.c | 6 +++--- kernel/sysctl.c | 2 +- kernel/time/itimer.c | 4 ++-- kernel/time/posix-cpu-timers.c | 2 +- kernel/tsacct.c | 2 +- kernel/workqueue.c | 6 +++--- lib/dump_stack.c | 2 +- lib/nlattr.c | 6 +++--- mm/compaction.c | 2 +- mm/filemap.c | 4 ++-- mm/gup.c | 2 +- mm/memfd.c | 2 +- mm/memory-failure.c | 10 +++++----- mm/memory.c | 2 +- mm/mmap.c | 4 ++-- mm/oom_kill.c | 18 +++++++++--------- mm/page_alloc.c | 4 ++-- mm/util.c | 2 +- net/core/sock.c | 2 +- net/dns_resolver/internal.h | 2 +- net/ipv4/raw.c | 2 +- net/ipv4/tcp.c | 2 +- net/socket.c | 2 +- security/lsm_audit.c | 4 ++-- 90 files changed, 184 insertions(+), 165 deletions(-) -- 2.38.1
