Messages in this thread Patch in this message | | | Date | Sun, 21 Jul 2013 00:02:35 +0800 | Subject | Re: [ipc,shm] BUG: lock held when returning to user space! | From | Xiaotian Feng <> |
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On Sat, Jul 20, 2013 at 9:13 PM, Fengguang Wu <fengguang.wu@intel.com> wrote: > Greetings, > > I got the below dmesg and the first bad commit is > > commit c5d0282a0405b0a81fa3390e4230e4cbb3ced7a2 > Author: Davidlohr Bueso <davidlohr.bueso@hp.com> > Date: Fri Jul 19 09:56:58 2013 +1000 > > ipc,shm: shorten critical region for shmat > > Similar to other system calls, acquire the kern_ipc_perm lock after doing > the initial permission and security checks. > > Signed-off-by: Davidlohr Bueso <davidlohr.bueso@hp.com> > Tested-by: Sedat Dilek <sedat.dilek@gmail.com> > Cc: Rik van Riel <riel@redhat.com> > Cc: Manfred Spraul <manfred@colorfullife.com> > Signed-off-by: Andrew Morton <akpm@linux-foundation.org> > > [ 20.702156] > [ 20.702493] ================================================ > [ 20.703511] [ BUG: lock held when returning to user space! ] > [ 20.704532] 3.11.0-rc1-next-20130719 #50 Not tainted > [ 20.705416] ------------------------------------------------ > [ 20.706425] trinity-child0/174 is leaving the kernel with locks still held! > [ 20.707638] 1 lock held by trinity-child0/174: > [ 20.708475] #0: (rcu_read_lock){.+.+..}, at: [<ffffffff814a8491>] do_shmat+0xe1/0x500 >
---- ns = current->nsproxy->ipc_ns; - shp = shm_lock_check(ns, shmid); + rcu_read_lock(); + shp = shm_obtain_object_check(ns, shmid); if (IS_ERR(shp)) { err = PTR_ERR(shp); goto out; ----
If shm_obtain_object_check() failed, goto out will return with rcu_read_lock() held. I think following patch should cure this.
diff --git a/ipc/shm.c b/ipc/shm.c index 59f2194..cb2ceda 100644 --- a/ipc/shm.c +++ b/ipc/shm.c @@ -1093,7 +1093,7 @@ long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr, shp = shm_obtain_object_check(ns, shmid); if (IS_ERR(shp)) { err = PTR_ERR(shp); - goto out; + goto out_unlock; }
err = -EACCES;
> git bisect start c1f631b9a68251007a6353041ae90f9f7dca771c d03792f9db9b892f494d3aa19d767ddf0365d1ff -- > git bisect good 10a3f1f902465ae1320cc95a3284fd3697e05dd8 # 11:14 65+ binfmt_elf.c: use get_random_int() to fix entropy depleting > git bisect bad dac28788378838efb63e37a7eabd7729d97aba6b # 11:32 0- dcache: remove dentries from LRU before putting on dispose list > git bisect good 3140b2ed6dfe5c9e5eca371c77ca85dca05321d4 # 11:50 65+ ipc,shm: introduce shmctl_nolock > git bisect bad 48a91248649fa3327bd8a31c114ee9149a07f3a7 # 12:04 0- staging/lustre/ldlm: convert to shrinkers to count/scan API > git bisect good 98b78126a51aa5d3ee6d5dae5768e0d16deeeaa3 # 12:14 65+ ipc,shm: cleanup do_shmat pasta > git bisect bad 36ccfd799cad33e2edd5c14ac8776b33e63d195b # 12:14 0- ipc: rename ids->rw_mutex > git bisect bad c5d0282a0405b0a81fa3390e4230e4cbb3ced7a2 # 12:14 0- ipc,shm: shorten critical region for shmat > git bisect good 98b78126a51aa5d3ee6d5dae5768e0d16deeeaa3 # 15:34 195+ ipc,shm: cleanup do_shmat pasta > git bisect bad c1f631b9a68251007a6353041ae90f9f7dca771c # 15:34 0- Add linux-next specific files for 20130719 > git bisect good 709b465ee655387c4ec056383fa27f16c64f48db # 18:21 195+ Revert "ipc,shm: shorten critical region for shmat" > git bisect good d471ce53b1fab60110e4e9f647a345cea31752de # 18:44 195+ Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml > git bisect bad c1f631b9a68251007a6353041ae90f9f7dca771c # 18:44 0- Add linux-next specific files for 20130719 > > Thanks, > Fengguang
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