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author | Robin Holt <holt@sgi.com> | 2010-05-11 21:06:46 (GMT) |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-05-12 00:33:41 (GMT) |
commit | 34441427aab4bdb3069a4ffcda69a99357abcb2e (patch) | |
tree | 3beebde910f25b0945e9105017fd743c9e5241a5 /fs/proc/task_mmu.c | |
parent | 3c904afd7358e9ef515eb5df36b6f25c2b7fc2da (diff) | |
download | linux-fsl-qoriq-34441427aab4bdb3069a4ffcda69a99357abcb2e.tar.xz |
revert "procfs: provide stack information for threads" and its fixup commits
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>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/proc/task_mmu.c')
-rw-r--r-- | fs/proc/task_mmu.c | 19 |
1 files changed, 0 insertions, 19 deletions
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 0705534..47f5b14 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -247,25 +247,6 @@ static void show_map_vma(struct seq_file *m, struct vm_area_struct *vma) } else if (vma->vm_start <= mm->start_stack && vma->vm_end >= mm->start_stack) { name = "[stack]"; - } else { - unsigned long stack_start; - struct proc_maps_private *pmp; - - pmp = m->private; - stack_start = pmp->task->stack_start; - - if (vma->vm_start <= stack_start && - vma->vm_end >= stack_start) { - pad_len_spaces(m, len); - seq_printf(m, - "[threadstack:%08lx]", -#ifdef CONFIG_STACK_GROWSUP - vma->vm_end - stack_start -#else - stack_start - vma->vm_start -#endif - ); - } } } else { name = "[vdso]"; |