The patch titled
Subject: proc: use down_read_killable mmap_sem for /proc/pid/map_files
has been added to the -mm tree. Its filename is
proc-use-down_read_killable-mmap_sem-for-proc-pid-map_files.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/proc-use-down_read_killable-mmap_sem-for-proc-pid-map_files.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/proc-use-down_read_killable-mmap_sem-for-proc-pid-map_files.patch
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx>
Subject: proc: use down_read_killable mmap_sem for /proc/pid/map_files
Do not remain stuck forever if something goes wrong. Using a killable
lock permits cleanup of stuck tasks and simplifies investigation.
It seems ->d_revalidate() could return any error (except ECHILD) to abort
validation and pass error as result of lookup sequence.
Link: http://lkml.kernel.org/r/156007493995.3335.9595044802115356911.stgit@buzz
Signed-off-by: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx>
Reviewed-by: Roman Gushchin <guro@xxxxxx>
Reviewed-by: Cyrill Gorcunov <gorcunov@xxxxxxxxx>
Reviewed-by: Kirill Tkhai <ktkhai@xxxxxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Cc: Alexey Dobriyan <adobriyan@xxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Michal Koutný <mkoutny@xxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/proc/base.c | 27 +++++++++++++++++++++------
1 file changed, 21 insertions(+), 6 deletions(-)
--- a/fs/proc/base.c~proc-use-down_read_killable-mmap_sem-for-proc-pid-map_files
+++ a/fs/proc/base.c
@@ -1962,9 +1962,12 @@ static int map_files_d_revalidate(struct
goto out;
if (!dname_to_vma_addr(dentry, &vm_start, &vm_end)) {
- down_read(&mm->mmap_sem);
- exact_vma_exists = !!find_exact_vma(mm, vm_start, vm_end);
- up_read(&mm->mmap_sem);
+ status = down_read_killable(&mm->mmap_sem);
+ if (!status) {
+ exact_vma_exists = !!find_exact_vma(mm, vm_start,
+ vm_end);
+ up_read(&mm->mmap_sem);
+ }
}
mmput(mm);
@@ -2010,8 +2013,11 @@ static int map_files_get_link(struct den
if (rc)
goto out_mmput;
+ rc = down_read_killable(&mm->mmap_sem);
+ if (rc)
+ goto out_mmput;
+
rc = -ENOENT;
- down_read(&mm->mmap_sem);
vma = find_exact_vma(mm, vm_start, vm_end);
if (vma && vma->vm_file) {
*path = vma->vm_file->f_path;
@@ -2107,7 +2113,10 @@ static struct dentry *proc_map_files_loo
if (!mm)
goto out_put_task;
- down_read(&mm->mmap_sem);
+ result = ERR_PTR(-EINTR);
+ if (down_read_killable(&mm->mmap_sem))
+ goto out_put_mm;
+
vma = find_exact_vma(mm, vm_start, vm_end);
if (!vma)
goto out_no_vma;
@@ -2118,6 +2127,7 @@ static struct dentry *proc_map_files_loo
out_no_vma:
up_read(&mm->mmap_sem);
+out_put_mm:
mmput(mm);
out_put_task:
put_task_struct(task);
@@ -2160,7 +2170,12 @@ proc_map_files_readdir(struct file *file
mm = get_task_mm(task);
if (!mm)
goto out_put_task;
- down_read(&mm->mmap_sem);
+
+ ret = down_read_killable(&mm->mmap_sem);
+ if (ret) {
+ mmput(mm);
+ goto out_put_task;
+ }
nr_files = 0;
_
Patches currently in -mm which might be from khlebnikov@xxxxxxxxxxxxxx are
proc-use-down_read_killable-mmap_sem-for-proc-pid-maps.patch
proc-use-down_read_killable-mmap_sem-for-proc-pid-smaps_rollup.patch
proc-use-down_read_killable-mmap_sem-for-proc-pid-pagemap.patch
proc-use-down_read_killable-mmap_sem-for-proc-pid-clear_refs.patch
proc-use-down_read_killable-mmap_sem-for-proc-pid-map_files.patch
mm-use-down_read_killable-for-locking-mmap_sem-in-access_remote_vm.patch
