The autoclose of BSD accounting writes a record to the BSD accounting
file. When mntput is called from moderaly deep within the stack the
(3KiB or so) generating I/O can be problemenatic as some I/O paths
require nearly 5KiB of stack on their own.
Avoid the possibility of stack overflow by moving the close of the BSD
accounting file into a work queue.
Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
---
kernel/acct.c | 25 ++++++++++++++++++++-----
1 file changed, 20 insertions(+), 5 deletions(-)
diff --git a/kernel/acct.c b/kernel/acct.c
index 8d6e145138bb..1853dd4a1d01 100644
--- a/kernel/acct.c
+++ b/kernel/acct.c
@@ -93,6 +93,7 @@ struct bsd_acct_struct {
static DEFINE_SPINLOCK(acct_lock);
static LIST_HEAD(acct_list);
+static LIST_HEAD(acct_close_list);
/*
* Check the amount of free space and suspend/resume accordingly.
@@ -280,6 +281,20 @@ SYSCALL_DEFINE1(acct, const char __user *, name)
return error;
}
+static void acct_close_mnts(struct work_struct *unused)
+{
+ struct bsd_acct_struct *acct;
+
+ spin_lock(&acct_lock);
+restart:
+ list_for_each_entry(acct, &acct_close_list, list) {
+ acct_file_reopen(acct, NULL, NULL);
+ goto restart;
+ }
+ spin_unlock(&acct_lock);
+}
+static DECLARE_WORK(acct_close_work, acct_close_mnts);
+
/**
* acct_auto_close - turn off a filesystem's accounting if it is on
* @m: vfsmount being shut down
@@ -289,15 +304,15 @@ SYSCALL_DEFINE1(acct, const char __user *, name)
*/
void acct_auto_close_mnt(struct vfsmount *m)
{
- struct bsd_acct_struct *acct;
+ struct bsd_acct_struct *acct, *tmp;
spin_lock(&acct_lock);
-restart:
- list_for_each_entry(acct, &acct_list, list)
+ list_for_each_entry_safe(acct, tmp, &acct_list, list) {
if (acct->file && acct->file->f_path.mnt == m) {
- acct_file_reopen(acct, NULL, NULL);
- goto restart;
+ list_move_tail(&acct->list, &acct_close_list);
+ schedule_work(&acct_close_work);
}
+ }
spin_unlock(&acct_lock);
}
--
1.9.1
--
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