From: Paul Fulghum Remove duplicate call to idr_remove() in ptmx_open. Error during open can result in call to release_dev() followed by call to idr_remove(). release_dev already calls idr_remove so the second call can cause a stack dump in idr_remove()->sub_remove() flagging an attempt to release an already released entry. I reproduces this on a machine with a misconfigured X server (attempting to restart multiple times rapidly) getting the same error as the 1st link below. This also seems to be related to: http://marc.theaimsgroup.com/?l=selinux&m=110536513426735&w=2 http://marc.theaimsgroup.com/?l=selinux&m=110596994916785&w=2 The stack dump can occur on close (as well as open) as shown in the 1st instance above, possible from something like: process A - open (index=0), open fail to out1, release_dev calls idr_remove (index 0), down(sem) sleeps process B - open (index=0), open OK (idr allocated) process A - wake and call idr_remove on index 0 ... process B - close, release_dev, stack dump on idr_remove (index=0) because entry already removed Signed-off-by: Andrew Morton --- drivers/char/tty_io.c | 1 + 1 files changed, 1 insertion(+) diff -puN drivers/char/tty_io.c~ptmx-fix-duplicate-idr_remove drivers/char/tty_io.c --- devel/drivers/char/tty_io.c~ptmx-fix-duplicate-idr_remove 2006-04-05 21:28:14.000000000 -0700 +++ devel-akpm/drivers/char/tty_io.c 2006-04-05 21:28:14.000000000 -0700 @@ -2195,6 +2195,7 @@ static int ptmx_open(struct inode * inod return 0; out1: release_dev(filp); + return retval; out: down(&allocated_ptys_lock); idr_remove(&allocated_ptys, index); _