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| author | Robin Holt <holt@sgi.com> | 2010-05-11 14:06:46 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2010-05-26 14:29:19 -0700 |
| commit | 92d664daf9de677afcbf392fac48b734d752abff (patch) | |
| tree | bc96a18e29f3269527c25d6662dabb36e607c1f4 /fs/proc/array.c | |
| parent | c8c4c2f04ba486355d7bc6d909a0723acd10f91d (diff) | |
| download | lwn-92d664daf9de677afcbf392fac48b734d752abff.tar.gz lwn-92d664daf9de677afcbf392fac48b734d752abff.zip | |
revert "procfs: provide stack information for threads" and its fixup commits
commit 34441427aab4bdb3069a4ffcda69a99357abcb2e upstream.
Originally, commit d899bf7b ("procfs: provide stack information for
threads") attempted to introduce a new feature for showing where the
threadstack was located and how many pages are being utilized by the
stack.
Commit c44972f1 ("procfs: disable per-task stack usage on NOMMU") was
applied to fix the NO_MMU case.
Commit 89240ba0 ("x86, fs: Fix x86 procfs stack information for threads on
64-bit") was applied to fix a bug in ia32 executables being loaded.
Commit 9ebd4eba7 ("procfs: fix /proc/<pid>/stat stack pointer for kernel
threads") was applied to fix a bug which had kernel threads printing a
userland stack address.
Commit 1306d603f ('proc: partially revert "procfs: provide stack
information for threads"') was then applied to revert the stack pages
being used to solve a significant performance regression.
This patch nearly undoes the effect of all these patches.
The reason for reverting these is it provides an unusable value in
field 28. For x86_64, a fork will result in the task->stack_start
value being updated to the current user top of stack and not the stack
start address. This unpredictability of the stack_start value makes
it worthless. That includes the intended use of showing how much stack
space a thread has.
Other architectures will get different values. As an example, ia64
gets 0. The do_fork() and copy_process() functions appear to treat the
stack_start and stack_size parameters as architecture specific.
I only partially reverted c44972f1 ("procfs: disable per-task stack usage
on NOMMU") . If I had completely reverted it, I would have had to change
mm/Makefile only build pagewalk.o when CONFIG_PROC_PAGE_MONITOR is
configured. Since I could not test the builds without significant effort,
I decided to not change mm/Makefile.
I only partially reverted 89240ba0 ("x86, fs: Fix x86 procfs stack
information for threads on 64-bit") . I left the KSTK_ESP() change in
place as that seemed worthwhile.
Signed-off-by: Robin Holt <holt@sgi.com>
Cc: Stefani Seibold <stefani@seibold.net>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'fs/proc/array.c')
| -rw-r--r-- | fs/proc/array.c | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/fs/proc/array.c b/fs/proc/array.c index 240787d2e998..725a650bbbb8 100644 --- a/fs/proc/array.c +++ b/fs/proc/array.c @@ -82,7 +82,6 @@ #include <linux/pid_namespace.h> #include <linux/ptrace.h> #include <linux/tracehook.h> -#include <linux/swapops.h> #include <asm/pgtable.h> #include <asm/processor.h> @@ -482,7 +481,7 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns, rsslim, mm ? mm->start_code : 0, mm ? mm->end_code : 0, - (permitted && mm) ? task->stack_start : 0, + (permitted && mm) ? mm->start_stack : 0, esp, eip, /* The signal information here is obsolete. |