linux/fs/proc, branch v3.5

vfs: Fix /proc//fdinfo/ file handling

2012-06-04T18:00:45Z

Cyrill Gorcunov reports that I broke the fdinfo files with commit 30a08bf2d31d ("proc: move fd symlink i_mode calculations into tid_fd_revalidate()"), and he's quite right. The tid_fd_revalidate() function is not just used for the /fd symlinks, it's also used for the /fdinfo/ files, and the permission model for those are different. So do the dynamic symlink permission handling just for symlinks, making the fdinfo files once more appear as the proper regular files they are. Of course, Al Viro argued (probably correctly) that we shouldn't do the symlink permission games at all, and make the symlinks always just be the normal 'lrwxrwxrwx'. That would have avoided this issue too, but since somebody noticed that the permissions had changed (which was the reason for that original commit 30a08bf2d31d in the first place), people do apparently use this feature. [ Basically, you can use the symlink permission data as a cheap "fdinfo" replacement, since you see whether the file is open for reading and/or writing by just looking at st_mode of the symlink. So the feature does make sense, even if the pain it has caused means we probably shouldn't have done it to begin with. ] Reported-and-tested-by: Cyrill Gorcunov Signed-off-by: Linus Torvalds

c/r: procfs: add arg_start/end, env_start/end and exit_code members to /proc/$pid/stat

2012-06-01T00:49:32Z

We would like to have an ability to restore command line arguments and program environment pointers but first we need to obtain them somehow. Thus we put these values into /proc/$pid/stat. The exit_code is needed to restore zombie tasks. Signed-off-by: Cyrill Gorcunov Acked-by: Kees Cook Cc: Pavel Emelyanov Cc: Serge Hallyn Cc: KAMEZAWA Hiroyuki Cc: Alexey Dobriyan Cc: Tejun Heo Cc: Andrew Vagin Cc: Vasiliy Kulikov Cc: Alexey Dobriyan Cc: "Eric W. Biederman" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

fs, proc: introduce /proc//task//children entry

2012-06-01T00:49:32Z

When we do checkpoint of a task we need to know the list of children the task, has but there is no easy and fast way to generate reverse parent->children chain from arbitrary (while a parent pid is provided in "PPid" field of /proc//status). So instead of walking over all pids in the system (creating one big process tree in memory, just to figure out which children a task has) -- we add explicit /proc//task//children entry, because the kernel already has this kind of information but it is not yet exported. This is a first level children, not the whole process tree. Signed-off-by: Cyrill Gorcunov Reviewed-by: Oleg Nesterov Reviewed-by: Kees Cook Cc: Pavel Emelyanov Cc: Serge Hallyn Cc: KAMEZAWA Hiroyuki Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

proc/smaps: show amount of nonlinear ptes in vma

2012-06-01T00:49:29Z

Currently, nonlinear mappings can not be distinguished from ordinary mappings. This patch adds into /proc/pid/smaps line "Nonlinear: kB", where size is amount of nonlinear ptes in vma, this line appears only if VM_NONLINEAR is set. This information may be useful not only for checkpoint/restore project. Requested by Pavel Emelyanov. Signed-off-by: Konstantin Khlebnikov Cc: Andi Kleen Cc: Pavel Emelyanov Cc: Alexey Dobriyan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

proc/smaps: carefully handle migration entries

2012-06-01T00:49:29Z

Currently smaps reports migration entries as "swap", as result "swap" can appears in shared mapping. This patch converts migration entries into pages and handles them as usual. Signed-off-by: Konstantin Khlebnikov Cc: Andi Kleen Cc: Pavel Emelyanov Cc: Alexey Dobriyan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

proc: report file/anon bit in /proc/pid/pagemap

2012-06-01T00:49:29Z

This is an implementation of Andrew's proposal to extend the pagemap file bits to report what is missing about tasks' working set. The problem with the working set detection is multilateral. In the criu (checkpoint/restore) project we dump the tasks' memory into image files and to do it properly we need to detect which pages inside mappings are really in use. The mincore syscall I though could help with this did not. First, it doesn't report swapped pages, thus we cannot find out which parts of anonymous mappings to dump. Next, it does report pages from page cache as present even if they are not mapped, and it doesn't make that has not been cow-ed. Note, that issue with swap pages is critical -- we must dump swap pages to image file. But the issues with file pages are optimization -- we can take all file pages to image, this would be correct, but if we know that a page is not mapped or not cow-ed, we can remove them from dump file. The dump would still be self-consistent, though significantly smaller in size (up to 10 times smaller on real apps). Andrew noticed, that the proc pagemap file solved 2 of 3 above issues -- it reports whether a page is present or swapped and it doesn't report not mapped page cache pages. But, it doesn't distinguish cow-ed file pages from not cow-ed. I would like to make the last unused bit in this file to report whether the page mapped into respective pte is PageAnon or not. [comment stolen from Pavel Emelyanov's v1 patch] Signed-off-by: Konstantin Khlebnikov Cc: Pavel Emelyanov Cc: Matt Mackall Cc: Hugh Dickins Cc: Rik van Riel Acked-by: KOSAKI Motohiro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

procfs: use more apprioriate types when dumping /proc/N/stat

2012-06-01T00:49:29Z

- use int fpr priority and nice, since task_nice()/task_prio() return that - field 24: get_mm_rss() returns unsigned long Signed-off-by: Jan Engelhardt Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

proc: pass "fd" by value in /proc/*/{fd,fdinfo} code

2012-06-01T00:49:29Z

Pass "fd" directly, not via pointer -- one less memory read. Signed-off-by: Alexey Dobriyan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

proc: don't do dummy rcu_read_lock/rcu_read_unlock on error path

2012-06-01T00:49:29Z

rcu_read_lock()/rcu_read_unlock() is nop for TINY_RCU, but is not a nop for, say, PREEMPT_RCU. proc_fill_cache() is called without RCU lock, there is no need to lock/unlock on error path, simply jump out of the loop. Signed-off-by: Alexey Dobriyan Cc: "Paul E. McKenney" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

proc: use mm_access() instead of ptrace_may_access()

2012-06-01T00:49:29Z

mm_access() handles this much better, and avoids some race conditions. Signed-off-by: Cong Wang Cc: Oleg Nesterov Cc: Alexey Dobriyan Cc: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds