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![Vlastimil Babka](/assets/img/avatar_default.png)
Patch series "cleanups and refactor of /proc/pid/smaps*". The recent regression in /proc/pid/smaps made me look more into the code. Especially the issues with smaps_rollup reported in [1] as explained in Patch 4, which fixes them by refactoring the code. Patches 2 and 3 are preparations for that. Patch 1 is me realizing that there's a lot of boilerplate left from times where we tried (unsuccessfuly) to mark thread stacks in the output. Originally I had also plans to rework the translation from /proc/pid/*maps* file offsets to the internal structures. Now the offset means "vma number", which is not really stable (vma's can come and go between read() calls) and there's an extra caching of last vma's address. My idea was that offsets would be interpreted directly as addresses, which would also allow meaningful seeks (see the ugly seek_to_smaps_entry() in tools/testing/selftests/vm/mlock2.h). However loff_t is (signed) long long so that might be insufficient somewhere for the unsigned long addresses. So the result is fixed issues with skewed /proc/pid/smaps_rollup results, simpler smaps code, and a lot of unused code removed. [1] https://marc.info/?l=linux-mm&m=151927723128134&w=2 This patch (of 4): Commitb76437579d
("procfs: mark thread stack correctly in proc/<pid>/maps") introduced differences between /proc/PID/maps and /proc/PID/task/TID/maps to mark thread stacks properly, and this was also done for smaps and numa_maps. However it didn't work properly and was ultimately removed by commitb18cb64ead
("fs/proc: Stop trying to report thread stacks"). Now the is_pid parameter for the related show_*() functions is unused and we can remove it together with wrapper functions and ops structures that differ for PID and TID cases only in this parameter. Link: http://lkml.kernel.org/r/20180723111933.15443-2-vbabka@suse.cz Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Reviewed-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Daniel Colascione <dancol@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
298 lines
6.6 KiB
C
298 lines
6.6 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/mm.h>
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#include <linux/file.h>
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#include <linux/fdtable.h>
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#include <linux/fs_struct.h>
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#include <linux/mount.h>
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#include <linux/ptrace.h>
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#include <linux/slab.h>
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#include <linux/seq_file.h>
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#include <linux/sched/mm.h>
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#include "internal.h"
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/*
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* Logic: we've got two memory sums for each process, "shared", and
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* "non-shared". Shared memory may get counted more than once, for
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* each process that owns it. Non-shared memory is counted
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* accurately.
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*/
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void task_mem(struct seq_file *m, struct mm_struct *mm)
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{
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struct vm_area_struct *vma;
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struct vm_region *region;
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struct rb_node *p;
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unsigned long bytes = 0, sbytes = 0, slack = 0, size;
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down_read(&mm->mmap_sem);
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for (p = rb_first(&mm->mm_rb); p; p = rb_next(p)) {
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vma = rb_entry(p, struct vm_area_struct, vm_rb);
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bytes += kobjsize(vma);
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region = vma->vm_region;
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if (region) {
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size = kobjsize(region);
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size += region->vm_end - region->vm_start;
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} else {
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size = vma->vm_end - vma->vm_start;
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}
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if (atomic_read(&mm->mm_count) > 1 ||
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vma->vm_flags & VM_MAYSHARE) {
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sbytes += size;
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} else {
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bytes += size;
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if (region)
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slack = region->vm_end - vma->vm_end;
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}
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}
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if (atomic_read(&mm->mm_count) > 1)
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sbytes += kobjsize(mm);
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else
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bytes += kobjsize(mm);
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if (current->fs && current->fs->users > 1)
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sbytes += kobjsize(current->fs);
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else
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bytes += kobjsize(current->fs);
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if (current->files && atomic_read(¤t->files->count) > 1)
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sbytes += kobjsize(current->files);
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else
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bytes += kobjsize(current->files);
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if (current->sighand && atomic_read(¤t->sighand->count) > 1)
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sbytes += kobjsize(current->sighand);
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else
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bytes += kobjsize(current->sighand);
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bytes += kobjsize(current); /* includes kernel stack */
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seq_printf(m,
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"Mem:\t%8lu bytes\n"
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"Slack:\t%8lu bytes\n"
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"Shared:\t%8lu bytes\n",
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bytes, slack, sbytes);
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up_read(&mm->mmap_sem);
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}
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unsigned long task_vsize(struct mm_struct *mm)
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{
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struct vm_area_struct *vma;
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struct rb_node *p;
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unsigned long vsize = 0;
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down_read(&mm->mmap_sem);
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for (p = rb_first(&mm->mm_rb); p; p = rb_next(p)) {
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vma = rb_entry(p, struct vm_area_struct, vm_rb);
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vsize += vma->vm_end - vma->vm_start;
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}
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up_read(&mm->mmap_sem);
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return vsize;
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}
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unsigned long task_statm(struct mm_struct *mm,
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unsigned long *shared, unsigned long *text,
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unsigned long *data, unsigned long *resident)
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{
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struct vm_area_struct *vma;
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struct vm_region *region;
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struct rb_node *p;
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unsigned long size = kobjsize(mm);
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down_read(&mm->mmap_sem);
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for (p = rb_first(&mm->mm_rb); p; p = rb_next(p)) {
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vma = rb_entry(p, struct vm_area_struct, vm_rb);
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size += kobjsize(vma);
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region = vma->vm_region;
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if (region) {
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size += kobjsize(region);
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size += region->vm_end - region->vm_start;
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}
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}
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*text = (PAGE_ALIGN(mm->end_code) - (mm->start_code & PAGE_MASK))
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>> PAGE_SHIFT;
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*data = (PAGE_ALIGN(mm->start_stack) - (mm->start_data & PAGE_MASK))
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>> PAGE_SHIFT;
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up_read(&mm->mmap_sem);
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size >>= PAGE_SHIFT;
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size += *text + *data;
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*resident = size;
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return size;
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}
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static int is_stack(struct vm_area_struct *vma)
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{
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struct mm_struct *mm = vma->vm_mm;
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/*
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* We make no effort to guess what a given thread considers to be
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* its "stack". It's not even well-defined for programs written
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* languages like Go.
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*/
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return vma->vm_start <= mm->start_stack &&
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vma->vm_end >= mm->start_stack;
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}
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/*
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* display a single VMA to a sequenced file
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*/
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static int nommu_vma_show(struct seq_file *m, struct vm_area_struct *vma)
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{
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struct mm_struct *mm = vma->vm_mm;
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unsigned long ino = 0;
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struct file *file;
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dev_t dev = 0;
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int flags;
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unsigned long long pgoff = 0;
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flags = vma->vm_flags;
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file = vma->vm_file;
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if (file) {
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struct inode *inode = file_inode(vma->vm_file);
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dev = inode->i_sb->s_dev;
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ino = inode->i_ino;
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pgoff = (loff_t)vma->vm_pgoff << PAGE_SHIFT;
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}
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seq_setwidth(m, 25 + sizeof(void *) * 6 - 1);
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seq_printf(m,
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"%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu ",
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vma->vm_start,
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vma->vm_end,
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flags & VM_READ ? 'r' : '-',
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flags & VM_WRITE ? 'w' : '-',
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flags & VM_EXEC ? 'x' : '-',
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flags & VM_MAYSHARE ? flags & VM_SHARED ? 'S' : 's' : 'p',
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pgoff,
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MAJOR(dev), MINOR(dev), ino);
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if (file) {
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seq_pad(m, ' ');
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seq_file_path(m, file, "");
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} else if (mm && is_stack(vma)) {
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seq_pad(m, ' ');
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seq_printf(m, "[stack]");
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}
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seq_putc(m, '\n');
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return 0;
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}
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/*
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* display mapping lines for a particular process's /proc/pid/maps
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*/
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static int show_map(struct seq_file *m, void *_p)
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{
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struct rb_node *p = _p;
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return nommu_vma_show(m, rb_entry(p, struct vm_area_struct, vm_rb));
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}
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static void *m_start(struct seq_file *m, loff_t *pos)
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{
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struct proc_maps_private *priv = m->private;
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struct mm_struct *mm;
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struct rb_node *p;
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loff_t n = *pos;
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/* pin the task and mm whilst we play with them */
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priv->task = get_proc_task(priv->inode);
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if (!priv->task)
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return ERR_PTR(-ESRCH);
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mm = priv->mm;
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if (!mm || !mmget_not_zero(mm))
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return NULL;
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down_read(&mm->mmap_sem);
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/* start from the Nth VMA */
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for (p = rb_first(&mm->mm_rb); p; p = rb_next(p))
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if (n-- == 0)
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return p;
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up_read(&mm->mmap_sem);
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mmput(mm);
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return NULL;
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}
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static void m_stop(struct seq_file *m, void *_vml)
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{
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struct proc_maps_private *priv = m->private;
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if (!IS_ERR_OR_NULL(_vml)) {
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up_read(&priv->mm->mmap_sem);
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mmput(priv->mm);
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}
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if (priv->task) {
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put_task_struct(priv->task);
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priv->task = NULL;
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}
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}
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static void *m_next(struct seq_file *m, void *_p, loff_t *pos)
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{
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struct rb_node *p = _p;
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(*pos)++;
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return p ? rb_next(p) : NULL;
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}
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static const struct seq_operations proc_pid_maps_ops = {
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.start = m_start,
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.next = m_next,
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.stop = m_stop,
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.show = show_map
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};
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static int maps_open(struct inode *inode, struct file *file,
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const struct seq_operations *ops)
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{
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struct proc_maps_private *priv;
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priv = __seq_open_private(file, ops, sizeof(*priv));
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if (!priv)
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return -ENOMEM;
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priv->inode = inode;
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priv->mm = proc_mem_open(inode, PTRACE_MODE_READ);
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if (IS_ERR(priv->mm)) {
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int err = PTR_ERR(priv->mm);
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seq_release_private(inode, file);
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return err;
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}
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return 0;
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}
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static int map_release(struct inode *inode, struct file *file)
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{
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struct seq_file *seq = file->private_data;
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struct proc_maps_private *priv = seq->private;
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if (priv->mm)
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mmdrop(priv->mm);
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return seq_release_private(inode, file);
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}
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static int pid_maps_open(struct inode *inode, struct file *file)
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{
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return maps_open(inode, file, &proc_pid_maps_ops);
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}
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const struct file_operations proc_pid_maps_operations = {
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.open = pid_maps_open,
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.read = seq_read,
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.llseek = seq_lseek,
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.release = map_release,
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};
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