Messages in this thread Patch in this message | | | Date | Thu, 23 Apr 2009 00:21:02 -0700 | From | Chris Wright <> | Subject | [patch 042/100] dm: path selector use module refcount directly |
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-stable review patch. If anyone has any objections, please let us know. ---------------------
From: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
upstream commit: aea9058801c0acfa2831af1714da412dfb0018c2
Fix refcount corruption in dm-path-selector
Refcounting with non-atomic ops under shared lock will corrupt the counter in multi-processor system and may trigger BUG_ON(). Use module refcount. # same approach as dm-target-use-module-refcount-directly.patch here # https://www.redhat.com/archives/dm-devel/2008-December/msg00075.html
Typical oops: kernel BUG at linux-2.6.29-rc3/drivers/md/dm-path-selector.c:90! Pid: 11148, comm: dmsetup Not tainted 2.6.29-rc3-nm #1 dm_put_path_selector+0x4d/0x61 [dm_multipath] Call Trace: [<ffffffffa031d3f9>] free_priority_group+0x33/0xb3 [dm_multipath] [<ffffffffa031d4aa>] free_multipath+0x31/0x67 [dm_multipath] [<ffffffffa031d50d>] multipath_dtr+0x2d/0x32 [dm_multipath] [<ffffffffa015d6c2>] dm_table_destroy+0x64/0xd8 [dm_mod] [<ffffffffa015b73a>] __unbind+0x46/0x4b [dm_mod] [<ffffffffa015b79f>] dm_swap_table+0x60/0x14d [dm_mod] [<ffffffffa015f963>] dev_suspend+0xfd/0x177 [dm_mod] [<ffffffffa0160250>] dm_ctl_ioctl+0x24c/0x29c [dm_mod] [<ffffffff80288cd3>] ? get_page_from_freelist+0x49c/0x61d [<ffffffffa015f866>] ? dev_suspend+0x0/0x177 [dm_mod] [<ffffffff802bf05c>] vfs_ioctl+0x2a/0x77 [<ffffffff802bf4f1>] do_vfs_ioctl+0x448/0x4a0 [<ffffffff802bf5a0>] sys_ioctl+0x57/0x7a [<ffffffff8020c05b>] system_call_fastpath+0x16/0x1b
Cc: stable@kernel.org Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com> Signed-off-by: Alasdair G Kergon <agk@redhat.com> Signed-off-by: Chris Wright <chrisw@sous-sol.org> --- drivers/md/dm-path-selector.c | 21 +++------------------ 1 file changed, 3 insertions(+), 18 deletions(-)
--- a/drivers/md/dm-path-selector.c +++ b/drivers/md/dm-path-selector.c @@ -17,9 +17,7 @@ struct ps_internal { struct path_selector_type pst; - struct list_head list; - long use; }; #define pst_to_psi(__pst) container_of((__pst), struct ps_internal, pst) @@ -45,12 +43,8 @@ static struct ps_internal *get_path_sele down_read(&_ps_lock); psi = __find_path_selector_type(name); - if (psi) { - if ((psi->use == 0) && !try_module_get(psi->pst.module)) - psi = NULL; - else - psi->use++; - } + if (psi && !try_module_get(psi->pst.module)) + psi = NULL; up_read(&_ps_lock); return psi; @@ -84,11 +78,7 @@ void dm_put_path_selector(struct path_se if (!psi) goto out; - if (--psi->use == 0) - module_put(psi->pst.module); - - BUG_ON(psi->use < 0); - + module_put(psi->pst.module); out: up_read(&_ps_lock); } @@ -136,11 +126,6 @@ int dm_unregister_path_selector(struct p return -EINVAL; } - if (psi->use) { - up_write(&_ps_lock); - return -ETXTBSY; - } - list_del(&psi->list); up_write(&_ps_lock);
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