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@pull pull bot commented Dec 3, 2020

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Alexander Aring and others added 7 commits November 24, 2020 23:45
Commit 0e539ca ("gfs2: Fix NULL pointer dereference in gfs2_rgrp_dump")
introduced additional locking in gfs2_rgrp_go_dump, which is also used for
dumping resource group glocks via debugfs.  However, on that code path, the
glock spin lock is already taken in dump_glock, and taking it again in
gfs2_glock2rgrp leads to deadlock.  This can be reproduced with:

  $ mkfs.gfs2 -O -p lock_nolock /dev/FOO
  $ mount /dev/FOO /mnt/foo
  $ touch /mnt/foo/bar
  $ cat /sys/kernel/debug/gfs2/FOO/glocks

Fix that by not taking the glock spin lock inside the go_dump callback.

Fixes: 0e539ca ("gfs2: Fix NULL pointer dereference in gfs2_rgrp_dump")
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
This patch introduce a new globs attribute to define the subclass of the
glock lockref spinlock. This avoid the following lockdep warning, which
occurs when we lock an inode lock while an iopen lock is held:

============================================
WARNING: possible recursive locking detected
5.10.0-rc3+ #4990 Not tainted
--------------------------------------------
kworker/0:1/12 is trying to acquire lock:
ffff9067d45672d8 (&gl->gl_lockref.lock){+.+.}-{3:3}, at: lockref_get+0x9/0x20

but task is already holding lock:
ffff9067da308588 (&gl->gl_lockref.lock){+.+.}-{3:3}, at: delete_work_func+0x164/0x260

other info that might help us debug this:
 Possible unsafe locking scenario:

       CPU0
       ----
  lock(&gl->gl_lockref.lock);
  lock(&gl->gl_lockref.lock);

 *** DEADLOCK ***

 May be due to missing lock nesting notation

3 locks held by kworker/0:1/12:
 #0: ffff9067c1bfdd38 ((wq_completion)delete_workqueue){+.+.}-{0:0}, at: process_one_work+0x1b7/0x540
 #1: ffffac594006be70 ((work_completion)(&(&gl->gl_delete)->work)){+.+.}-{0:0}, at: process_one_work+0x1b7/0x540
 #2: ffff9067da308588 (&gl->gl_lockref.lock){+.+.}-{3:3}, at: delete_work_func+0x164/0x260

stack backtrace:
CPU: 0 PID: 12 Comm: kworker/0:1 Not tainted 5.10.0-rc3+ #4990
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-2.fc32 04/01/2014
Workqueue: delete_workqueue delete_work_func
Call Trace:
 dump_stack+0x8b/0xb0
 __lock_acquire.cold+0x19e/0x2e3
 lock_acquire+0x150/0x410
 ? lockref_get+0x9/0x20
 _raw_spin_lock+0x27/0x40
 ? lockref_get+0x9/0x20
 lockref_get+0x9/0x20
 delete_work_func+0x188/0x260
 process_one_work+0x237/0x540
 worker_thread+0x4d/0x3b0
 ? process_one_work+0x540/0x540
 kthread+0x127/0x140
 ? __kthread_bind_mask+0x60/0x60
 ret_from_fork+0x22/0x30

Suggested-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
If gfs2 tries to mount a (corrupt) file system that has no resource
groups it still tries to set preferences on the first one, which causes
a kernel null pointer dereference. This patch adds a check to function
gfs2_ri_update so this condition is detected and reported back as an
error.

Reported-by: syzbot+e3f23ce40269a4c9053a@syzkaller.appspotmail.com
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
GFS2's freeze/thaw mechanism uses a special freeze glock to control its
operation. It does this with a sync glock operation (glops.c) called
freeze_go_sync. When the freeze glock is demoted (glock's do_xmote) the
glops function causes the file system to be frozen. This is intended. However,
GFS2's mount and unmount processes also hold the freeze glock to prevent other
processes, perhaps on different cluster nodes, from mounting the frozen file
system in read-write mode.

Before this patch, there was no check in freeze_go_sync for whether a freeze
in intended or whether the glock demote was caused by a normal unmount.
So it was trying to freeze the file system it's trying to unmount, which
ends up in a deadlock.

This patch adds an additional check to freeze_go_sync so that demotes of the
freeze glock are ignored if they come from the unmount process.

Fixes: 20b3291 ("gfs2: Fix regression in freeze_go_sync")
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Commit 20f8299 ("gfs2: Rework read and page fault locking") lifted
the glock lock taking from the low-level ->readpage and ->readahead
address space operations to the higher-level ->read_iter file and
->fault vm operations.  The glocks are still taken in LM_ST_SHARED mode
only.  On filesystems mounted without the noatime option, ->read_iter
sometimes needs to update the atime as well, though.  Right now, this
leads to a failed locking mode assertion in gfs2_dirty_inode.

Fix that by introducing a new update_time inode operation.  There, if
the glock is held non-exclusively, upgrade it to an exclusive lock.

Reported-by: Alexander Aring <aahringo@redhat.com>
Fixes: 20f8299 ("gfs2: Rework read and page fault locking")
Cc: stable@vger.kernel.org # v5.8+
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
…e_work_func

In gfs2_create_inode and gfs2_inode_lookup, make sure to cancel any pending
delete work before taking the inode glock.  Otherwise, gfs2_cancel_delete_work
may block waiting for delete_work_func to complete, and delete_work_func may
block trying to acquire the inode glock in gfs2_inode_lookup.

Reported-by: Alexander Aring <aahringo@redhat.com>
Fixes: a0e3cc6 ("gfs2: Turn gl_delete into a delayed work")
Cc: stable@vger.kernel.org # v5.8+
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
…x/kernel/git/gfs2/linux-gfs2

Pull gfs2 fixes from Andreas Gruenbacher:
 "Various gfs2 fixes"

* tag 'gfs2-v5.10-rc5-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2:
  gfs2: Fix deadlock between gfs2_{create_inode,inode_lookup} and delete_work_func
  gfs2: Upgrade shared glocks for atime updates
  gfs2: Don't freeze the file system during unmount
  gfs2: check for empty rgrp tree in gfs2_ri_update
  gfs2: set lockdep subclass for iopen glocks
  gfs2: Fix deadlock dumping resource group glocks
@pull pull bot added the ⤵️ pull label Dec 3, 2020
@pull pull bot merged commit 34816d2 into bergwolf:master Dec 3, 2020
pull bot pushed a commit that referenced this pull request Jul 13, 2024
Add a test case which replaces an active ingress qdisc while keeping the
miniq in-tact during the transition period to the new clsact qdisc.

  # ./vmtest.sh -- ./test_progs -t tc_link
  [...]
  ./test_progs -t tc_link
  [    3.412871] bpf_testmod: loading out-of-tree module taints kernel.
  [    3.413343] bpf_testmod: module verification failed: signature and/or required key missing - tainting kernel
  #332     tc_links_after:OK
  #333     tc_links_append:OK
  #334     tc_links_basic:OK
  #335     tc_links_before:OK
  #336     tc_links_chain_classic:OK
  #337     tc_links_chain_mixed:OK
  #338     tc_links_dev_chain0:OK
  #339     tc_links_dev_cleanup:OK
  #340     tc_links_dev_mixed:OK
  #341     tc_links_ingress:OK
  #342     tc_links_invalid:OK
  #343     tc_links_prepend:OK
  #344     tc_links_replace:OK
  #345     tc_links_revision:OK
  Summary: 14/0 PASSED, 0 SKIPPED, 0 FAILED

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20240708133130.11609-2-daniel@iogearbox.net
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
pull bot pushed a commit that referenced this pull request Nov 21, 2024
Add three tests for struct_ops using private stack.
  ./test_progs -t struct_ops_private_stack
  #336/1   struct_ops_private_stack/private_stack:OK
  #336/2   struct_ops_private_stack/private_stack_fail:OK
  #336/3   struct_ops_private_stack/private_stack_recur:OK
  #336     struct_ops_private_stack:OK

The following is a snippet of a struct_ops check_member() implementation:

	u32 moff = __btf_member_bit_offset(t, member) / 8;
	switch (moff) {
	case offsetof(struct bpf_testmod_ops3, test_1):
        	prog->aux->priv_stack_requested = true;
                prog->aux->recursion_detected = test_1_recursion_detected;
        	fallthrough;
	default:
        	break;
	}
	return 0;

The first test is with nested two different callback functions where the
first prog has more than 512 byte stack size (including subprogs) with
private stack enabled.

The second test is a negative test where the second prog has more than 512
byte stack size without private stack enabled.

The third test is the same callback function recursing itself. At run time,
the jit trampoline recursion check kicks in to prevent the recursion. The
recursion_detected() callback function is implemented by the bpf_testmod,
the following message in dmesg
  bpf_testmod: oh no, recursing into test_1, recursion_misses 1
demonstrates the callback function is indeed triggered when recursion miss
happens.

Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20241112163938.2225528-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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2 participants