On Mon, Jun 13, 2016 at 2:13 PM, Topi Miettinen <toiwoton@xxxxxxxxx> wrote: > On 06/13/16 20:40, Andy Lutomirski wrote: >> On 06/13/2016 12:44 PM, Topi Miettinen wrote: >>> Track maximum number of files for the process, present current maximum >>> in /proc/self/limits. >> >> The core part should be its own patch. >> >> Also, you have this weirdly named (and racy!) function bump_rlimit. > > I can change the name if you have better suggestions. rlimit_track_max? > > The max value is written often but read seldom, if ever. What kind of > locking should I use then? Possibly none, but WRITE_ONCE would be good as would a comment indicating that your code in intentionally racy. Or you could use atomic_cmpxchg if that won't kill performance. rlimit_track_max sounds like a better name to me. > >> Wouldn't this be nicer if you taught the rlimit code to track the >> *current* usage generically and to derive the max usage from that? > > Current rlimit code performs checks against current limits. These are > typically done early in the calling function and further checks could > also fail. Thus max should not be updated until much later. Maybe these > could be combined, but not easily if at all. I mean: why not actually show the current value in /proc/pid/limits and track the max via whatever teaches proc about the current value? > >> >>> diff --git a/fs/proc/base.c b/fs/proc/base.c >>> index a11eb71..227997b 100644 >>> --- a/fs/proc/base.c >>> +++ b/fs/proc/base.c >>> @@ -630,8 +630,8 @@ static int proc_pid_limits(struct seq_file *m, >>> struct pid_namespace *ns, >>> /* >>> * print the file header >>> */ >>> - seq_printf(m, "%-25s %-20s %-20s %-10s\n", >>> - "Limit", "Soft Limit", "Hard Limit", "Units"); >>> + seq_printf(m, "%-25s %-20s %-20s %-10s %-20s\n", >>> + "Limit", "Soft Limit", "Hard Limit", "Units", "Max"); >> >> What existing programs, if any, does this break? > > Using Debian codesearch for /limits" string, I'd check pam_limits and > rtkit. The max values could be put into a new file if you prefer. If it actually breaks them, then you need to change the patch so you don't break them. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
