From: email@example.com (Eric W. Biederman) To: Geoff Levand <firstname.lastname@example.org> Cc: Arnd Bergmann <email@example.com>, Linus Torvalds <firstname.lastname@example.org>, Oleg Nesterov <email@example.com>, Linux Kernel Mailing List <firstname.lastname@example.org>, linux-fsdevel <email@example.com>, Alexander Viro <firstname.lastname@example.org>, Michael Ellerman <email@example.com>, Arnd Bergmann <firstname.lastname@example.org> Subject: Re: [PATCH v2 02/24] exec: Simplify unshare_files Date: Tue, 24 Nov 2020 19:16:14 -0600 [thread overview] Message-ID: <email@example.com> (raw) In-Reply-To: <firstname.lastname@example.org> (Geoff Levand's message of "Tue, 24 Nov 2020 15:44:50 -0800") Geoff Levand <email@example.com> writes: > On 11/24/20 12:14 PM, Arnd Bergmann wrote: >> On Tue, Nov 24, 2020 at 8:58 PM Linus Torvalds >> <firstname.lastname@example.org> wrote: >>> >>> On Tue, Nov 24, 2020 at 11:55 AM Eric W. Biederman >>> <email@example.com> wrote: >>>> >>>> If cell happens to be dead we can remove a fair amount of generic kernel >>>> code that only exists to support cell. >>> >>> Even if some people might still use cell (which sounds unlikely), I >>> think we can remove the spu core dumping code. >> >> The Cell blade hardware (arch/powerpc/platforms/cell/) that I'm listed >> as a maintainer for is very much dead, but there is apparently still some >> activity on the Playstation 3 that Geoff Levand maintains. >> >> Eric correctly points out that the PS3 firmware no longer boots >> Linux (OtherOS), but AFAIK there are both users with old firmware >> and those that use a firmware exploit to run homebrew code including >> Linux. >> >> I would assume they still use the SPU and might also use the core >> dump code in particular. Let's see what Geoff thinks. > > There are still PS3-Linux users out there. They use 'Homebrew' firmware > released through 'Hacker' forums that allow them to run Linux on > non-supported systems. They are generally hobbies who don't post to > Linux kernel mailing lists. I get direct inquiries regularly asking > about how to update to a recent kernel. One of the things that attract > them to the PS3 is the Cell processor and either using or programming > the SPUs. > > It is difficult to judge how much use the SPU core dump support gets, > but if it is not a cause of major problems I feel we should consider > keeping it. I just took a quick look to get a sense how much tool support there is. In the gdb tree I found this 2019 commit abf516c6931a ("Remove Cell Broadband Engine debugging support"). Which basically removes the code in gdb that made sense of the spu coredumps. I would not say the coredump support is a source major problems, but it is a challenge to understand. One of the pieces of code in there that is necessary to make the coredump support work reliable, a call to unshare_files, Oleg whole essentially maintains the ptrace and coredump support did not know why it was there, and it was not at all obvious when I looked at the code. So we are certainly in maintainers loosing hours of time figuring out what is going on and spending time fixing fuzzer bugs related to the code. At the minimum I will add a few more comments so people reading the code can realize why it is there. Perhaps putting the relevant code behind a Kconfig so it is only built into the kernel when spufs is present. I think we are at a point we we can start planning on removing the coredump support. The tools to read it are going away. None of what is there is bad, but it is definitely a special case, and it definitely has a maintenance cost. Eric
next prev parent reply other threads:[~2020-11-25 1:16 UTC|newest] Thread overview: 77+ messages / expand[flat|nested] mbox.gz Atom feed top [not found] <firstname.lastname@example.org> 2020-11-20 23:14 ` [PATCH v2 01/24] exec: Move unshare_files to fix posix file locking during exec Eric W. Biederman 2020-11-20 23:58 ` Linus Torvalds 2020-12-07 22:22 ` Al Viro [not found] ` <email@example.com> 2020-12-07 23:35 ` Al Viro 2020-11-20 23:14 ` [PATCH v2 02/24] exec: Simplify unshare_files Eric W. Biederman 2020-11-23 17:50 ` Oleg Nesterov 2020-11-23 18:25 ` Linus Torvalds [not found] ` <firstname.lastname@example.org> [not found] ` <email@example.com> 2020-11-24 19:58 ` Linus Torvalds 2020-11-24 20:14 ` Arnd Bergmann 2020-11-24 23:44 ` Geoff Levand 2020-11-25 1:16 ` Eric W. Biederman [this message] 2020-11-27 20:29 ` Arnd Bergmann 2020-11-30 21:37 ` Eric W. Biederman 2020-12-01 9:46 ` Michael Ellerman 2020-11-25 21:51 ` [RFC][PATCH] coredump: Document coredump code exclusively used by cell spufs Eric W. Biederman 2020-12-02 15:20 ` Eric W. Biederman 2020-12-02 15:58 ` Arnd Bergmann 2020-12-07 22:32 ` [PATCH v2 02/24] exec: Simplify unshare_files Al Viro 2020-11-20 23:14 ` [PATCH v2 03/24] exec: Remove reset_files_struct Eric W. Biederman 2020-11-20 23:14 ` [PATCH v2 04/24] kcmp: In kcmp_epoll_target use fget_task Eric W. Biederman 2020-11-20 23:14 ` [PATCH v2 05/24] bpf: In bpf_task_fd_query " Eric W. Biederman 2020-11-20 23:14 ` [PATCH v2 06/24] proc/fd: In proc_fd_link " Eric W. Biederman 2020-11-20 23:14 ` [PATCH v2 07/24] file: Rename __fcheck_files to files_lookup_fd_raw Eric W. Biederman 2020-11-20 23:14 ` [PATCH v2 08/24] file: Factor files_lookup_fd_locked out of fcheck_files Eric W. Biederman 2020-11-20 23:14 ` [PATCH v2 09/24] file: Replace fcheck_files with files_lookup_fd_rcu Eric W. Biederman 2020-12-07 22:46 ` Al Viro 2020-12-07 22:49 ` Al Viro 2020-12-09 16:54 ` Al Viro 2020-12-09 17:44 ` Paul E. McKenney 2020-11-20 23:14 ` [PATCH v2 10/24] file: Rename fcheck lookup_fd_rcu Eric W. Biederman 2020-11-20 23:14 ` [PATCH v2 11/24] file: Implement task_lookup_fd_rcu Eric W. Biederman 2020-11-21 18:19 ` Cyrill Gorcunov [not found] ` <firstname.lastname@example.org> 2020-11-22 13:52 ` Cyrill Gorcunov 2020-11-20 23:14 ` [PATCH v2 12/24] proc/fd: In tid_fd_mode use task_lookup_fd_rcu Eric W. Biederman 2020-11-20 23:14 ` [PATCH v2 13/24] kcmp: In get_file_raw_ptr " Eric W. Biederman 2020-11-23 21:05 ` Cyrill Gorcunov 2020-11-20 23:14 ` [PATCH v2 14/24] file: Implement task_lookup_next_fd_rcu Eric W. Biederman 2020-11-20 23:14 ` [PATCH v2 15/24] proc/fd: In proc_readfd_common use task_lookup_next_fd_rcu Eric W. Biederman 2020-12-07 23:29 ` Al Viro [not found] ` <email@example.com> 2020-12-09 4:07 ` Al Viro [not found] ` <firstname.lastname@example.org> 2020-12-09 14:23 ` Al Viro 2020-12-09 18:04 ` [PATCH] files: rcu free files_struct Eric W. Biederman 2020-12-09 19:13 ` Linus Torvalds 2020-12-09 19:50 ` Al Viro 2020-12-09 21:32 ` Eric W. Biederman 2020-12-10 6:13 ` Al Viro 2020-12-10 19:29 ` Eric W. Biederman 2020-12-10 21:36 ` Al Viro 2020-12-10 22:30 ` Christian Brauner 2020-12-10 22:54 ` Al Viro 2020-12-10 23:10 ` Al Viro 2020-12-09 21:42 ` [PATCH -1/24] exec: Don't open code get_close_on_exec Eric W. Biederman 2020-12-09 22:04 ` [PATCH] files: rcu free files_struct Eric W. Biederman 2020-12-09 19:49 ` Matthew Wilcox 2020-12-09 22:06 ` Eric W. Biederman 2020-12-09 22:58 ` Al Viro 2020-12-09 23:01 ` Linus Torvalds 2020-12-09 23:04 ` Linus Torvalds 2020-12-09 23:07 ` Matthew Wilcox 2020-12-09 23:26 ` Paul E. McKenney 2020-12-09 23:29 ` Linus Torvalds 2020-12-10 0:39 ` Paul E. McKenney 2020-12-10 0:41 ` Linus Torvalds 2020-12-10 0:57 ` Paul E. McKenney 2020-11-20 23:14 ` [PATCH v2 16/24] bpf/task_iter: In task_file_seq_get_next use task_lookup_next_fd_rcu Eric W. Biederman 2020-11-23 17:06 ` Yonghong Song 2020-11-20 23:14 ` [PATCH v2 17/24] proc/fd: In fdinfo seq_show don't use get_files_struct Eric W. Biederman 2020-11-20 23:14 ` [PATCH v2 18/24] file: Merge __fd_install into fd_install Eric W. Biederman 2020-11-20 23:14 ` [PATCH v2 19/24] file: In f_dupfd read RLIMIT_NOFILE once Eric W. Biederman 2020-11-20 23:14 ` [PATCH v2 20/24] file: Merge __alloc_fd into alloc_fd Eric W. Biederman 2020-11-20 23:14 ` [PATCH v2 21/24] file: Rename __close_fd to close_fd and remove the files parameter Eric W. Biederman 2020-11-20 23:14 ` [PATCH v2 22/24] file: Replace ksys_close with close_fd Eric W. Biederman 2020-11-20 23:14 ` [PATCH v2 23/24] file: Rename __close_fd_get_file close_fd_get_file Eric W. Biederman 2020-11-20 23:14 ` [PATCH v2 24/24] file: Remove get_files_struct Eric W. Biederman 2020-11-21 0:05 ` [PATCH v2 00/24] exec: Move unshare_files and guarantee files_struct.count is correct Linus Torvalds 2020-11-28 5:12 ` Al Viro 2020-12-07 23:56 ` Al Viro
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