Re: [bisected] Stack overflow after fs: "switch the IO-triggering parts of umount to fs_pin" (was net namespaces kernel stack overflow)

2018-04-19 Thread Alexander Aring
Hi, On Thu, Apr 19, 2018 at 12:56 PM, Kirill Tkhai wrote: > On 19.04.2018 19:44, Al Viro wrote: >> On Thu, Apr 19, 2018 at 04:34:48PM +0100, Al Viro wrote: >> >>> IOW, we only get there if our vfsmount was an MNT_INTERNAL one. >>> So we have mnt->mnt_umount of some MNT_INTERNAL mount found in >>>

Re: [bisected] Stack overflow after fs: "switch the IO-triggering parts of umount to fs_pin" (was net namespaces kernel stack overflow)

2018-04-19 Thread Kirill Tkhai
On 19.04.2018 19:44, Al Viro wrote: > On Thu, Apr 19, 2018 at 04:34:48PM +0100, Al Viro wrote: > >> IOW, we only get there if our vfsmount was an MNT_INTERNAL one. >> So we have mnt->mnt_umount of some MNT_INTERNAL mount found in >> ->mnt_pins of some other mount. Which, AFAICS, means that >> it

Re: [bisected] Stack overflow after fs: "switch the IO-triggering parts of umount to fs_pin" (was net namespaces kernel stack overflow)

2018-04-19 Thread Al Viro
On Thu, Apr 19, 2018 at 04:34:48PM +0100, Al Viro wrote: > IOW, we only get there if our vfsmount was an MNT_INTERNAL one. > So we have mnt->mnt_umount of some MNT_INTERNAL mount found in > ->mnt_pins of some other mount. Which, AFAICS, means that > it used to be mounted on that other mount. How

Re: [bisected] Stack overflow after fs: "switch the IO-triggering parts of umount to fs_pin" (was net namespaces kernel stack overflow)

2018-04-19 Thread Al Viro
On Thu, Apr 19, 2018 at 03:50:25PM +0300, Kirill Tkhai wrote: > Hi, Al, > > commit 87b95ce0964c016ede92763be9c164e49f1019e9 is the first after which the > below test crashes the kernel: > > Author: Al Viro > Date: Sat Jan 10 19:01:08 2015 -0500 > > switch the IO-triggering parts

[bisected] Stack overflow after fs: "switch the IO-triggering parts of umount to fs_pin" (was net namespaces kernel stack overflow)

2018-04-19 Thread Kirill Tkhai
Hi, Al, commit 87b95ce0964c016ede92763be9c164e49f1019e9 is the first after which the below test crashes the kernel: Author: Al Viro Date: Sat Jan 10 19:01:08 2015 -0500 switch the IO-triggering parts of umount to fs_pin Signed-off-by: Al Viro $modprobe dummy $while tr