Thread (34 messages) 34 messages, 4 authors, 2023-12-07

Re: [PATCH 05/11] selinux: use dlist for isec inode list

From: Dave Chinner <david@fromorbit.com>
Date: 2023-12-06 23:04:59
Also in: dm-devel, gfs2, linux-block, linux-fsdevel, lkml, selinux

On Wed, Dec 06, 2023 at 04:52:42PM -0500, Paul Moore wrote:
On Wed, Dec 6, 2023 at 1:07 AM Dave Chinner [off-list ref] wrote:
quoted
From: Dave Chinner <redacted>

Because it's a horrible point of lock contention under heavily
concurrent directory traversals...

  - 12.14% d_instantiate
     - 12.06% security_d_instantiate
        - 12.13% selinux_d_instantiate
           - 12.16% inode_doinit_with_dentry
              - 15.45% _raw_spin_lock
                 - do_raw_spin_lock
                      14.68% __pv_queued_spin_lock_slowpath


Signed-off-by: Dave Chinner <redacted>
---
 include/linux/dlock-list.h        |  9 ++++
 security/selinux/hooks.c          | 72 +++++++++++++++----------------
 security/selinux/include/objsec.h |  6 +--
 3 files changed, 47 insertions(+), 40 deletions(-)
In the cover letter you talk about testing, but I didn't see any
mention of testing with SELinux enabled.  Given the lock contention
stats in the description above I'm going to assume you did test this
and pass along my ACK, but if you haven't tested the changes below
please do before sending this anywhere important.
AFAIA, I've been testing with selinux enabled - I'm trying to run
these tests in an environment as close to typical production systems
as possible and that means selinux needs to be enabled.

As such, all the fstests and perf testing has been done with selinux
in permissive mode using "-o context=system_u:object_r:root_t:s0" as
the default context for the mount.

I see this sort of thing in the profiles:

- 87.13% path_lookupat
   - 86.46% walk_component
      - 84.20% lookup_slow
	 - 84.05% __lookup_slow
	    - 80.81% xfs_vn_lookup
	       - 77.84% xfs_lookup
....
	       - 2.91% d_splice_alias
		  - 1.52% security_d_instantiate
		     - 1.50% selinux_d_instantiate
			- 1.47% inode_doinit_with_dentry
			   - 0.83% inode_doinit_use_xattr
				0.52% __vfs_getxattr

Which tells me that selinux is definitely doing -something- on every
inode being instantiated, so I'm pretty sure the security and
selinux paths are getting exercised...
Acked-by: Paul Moore <paul@paul-moore.com>
Thanks!

-Dave.
-- 
Dave Chinner
david@fromorbit.com
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