| Message ID | 20130628134749.2058ab52184a7259c2d9379e@linux-foundation.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Acked-by: Sunil Mushran <sunil.mushran@gmail.com> On Fri, Jun 28, 2013 at 1:47 PM, Andrew Morton <akpm@linux-foundation.org>wrote: > On Sun, 23 Jun 2013 18:39:16 +0800 Jeff Liu <jeff.liu@oracle.com> wrote: > > > Hi Jiufei, > > > > On 06/20/2013 07:13 PM, Xue jiufei wrote: > > > > > Function dlmlock_master() returns DLM_RECOVERING/DLM_MIGRATING/ > > > DLM_FORWAR after adding lock to blocked list if lockres has the state > > > DLM_LOCK_RES_RECOVERING/DLM_LOCK_RES_MIGRATING/ > > > DLM_LOCK_RES_IN_PROGRESS. so it will retry in dlmlock(). And this may > > > cause dlm_thread fall into an infinite loop > > > > > > Thread1 dlm_thread > > > calls dlm_lock->dlmlock_master, > > > if lockresA is in state > > > DLM_LOCK_RES_RECOVERING, calls > > > __dlm_wait_on_lockres() and waits > > > until others threads clear this > > > state; > > > > > > If cannot grant this lock, > > > adding lock to blocked list, > > > and return DLM_RECOVERING; > > > > > > Grant this lock and move it to > > > grant list; > > > > > > After a while, retry and > > > calls list_add_tail(), adding lock > > > to blocked list again. > > > > > > Granted and blocked list of this lockres will become the following > > > conditions: > > > lock_res->granted.next = dlm_lock->list_head; > > > lock_res->blocked.next = dlm_lock->list_head; > > > dlm_lock->list_head.next = dlm_lock_resource->blocked; > > > When dlm_thread traverses the granted list, it will fall into an > > > endless loop, checking dlm_lock.list_head, dlm_lock->list_head.next > > > (i.e.lock_res->blocked), lock_res->blocked.next(i.e.dlm_lock.list_head > > > again) ..... > > > > Thanks for your nice description of this problem and this fix looks good. > > Let's waiting for an ACK from either Sunil, Mark or Joel. > > Still waiting ;) > > > From: Xue jiufei <xuejiufei@huawei.com> > Subject: ocfs2: dlmlock_master() should return DLM_NORMAL after adding > lock to blocked list > > dlmlock_master() returns DLM_RECOVERING/DLM_MIGRATING/ DLM_FORWAR after > adding lock to blocked list if lockres has the state > DLM_LOCK_RES_RECOVERING/DLM_LOCK_RES_MIGRATING/ DLM_LOCK_RES_IN_PROGRESS. > so it will retry in dlmlock(). And this may cause dlm_thread fall into an > infinite loop > > Thread1 dlm_thread > calls dlm_lock->dlmlock_master, > if lockresA is in state > DLM_LOCK_RES_RECOVERING, calls > __dlm_wait_on_lockres() and waits > until others threads clear this > state; > > If cannot grant this lock, > adding lock to blocked list, > and return DLM_RECOVERING; > > Grant this lock and move it to > grant list; > > After a while, retry and > calls list_add_tail(), adding lock > to blocked list again. > > Granted and blocked list of this lockres will become the following > conditions: > > lock_res->granted.next = dlm_lock->list_head; > lock_res->blocked.next = dlm_lock->list_head; > dlm_lock->list_head.next = dlm_lock_resource->blocked; > > When dlm_thread traverses the granted list, it will fall into an endless > loop, checking dlm_lock.list_head, dlm_lock->list_head.next > (i.e.lock_res->blocked), lock_res->blocked.next(i.e.dlm_lock.list_head > again) ..... > > Signed-off-by: joyce <xuejiufei@huawei.com> > Reviewed-by: jensen <shencanquan@huawei.com> > Cc: Jeff Liu <jeff.liu@oracle.com> > Cc: Sunil Mushran <sunil.mushran@gmail.com> > Cc: Mark Fasheh <mfasheh@suse.com> > Cc: Joel Becker <jlbec@evilplan.org> > Signed-off-by: Andrew Morton <akpm@linux-foundation.org> > --- > > fs/ocfs2/dlm/dlmlock.c | 1 + > 1 file changed, 1 insertion(+) > > diff -puN > fs/ocfs2/dlm/dlmlock.c~ocfs2-dlmlock_master-should-return-dlm_normal-after-adding-lock-to-blocked-list > fs/ocfs2/dlm/dlmlock.c > --- > a/fs/ocfs2/dlm/dlmlock.c~ocfs2-dlmlock_master-should-return-dlm_normal-after-adding-lock-to-blocked-list > +++ a/fs/ocfs2/dlm/dlmlock.c > @@ -178,6 +178,7 @@ static enum dlm_status dlmlock_master(st > lock->ml.node); > } > } else { > + status = DLM_NORMAL; > dlm_lock_get(lock); > list_add_tail(&lock->list, &res->blocked); > kick_thread = 1; > _ > > > _______________________________________________ > Ocfs2-devel mailing list > Ocfs2-devel@oss.oracle.com > https://oss.oracle.com/mailman/listinfo/ocfs2-devel >
diff -puN fs/ocfs2/dlm/dlmlock.c~ocfs2-dlmlock_master-should-return-dlm_normal-after-adding-lock-to-blocked-list fs/ocfs2/dlm/dlmlock.c --- a/fs/ocfs2/dlm/dlmlock.c~ocfs2-dlmlock_master-should-return-dlm_normal-after-adding-lock-to-blocked-list +++ a/fs/ocfs2/dlm/dlmlock.c @@ -178,6 +178,7 @@ static enum dlm_status dlmlock_master(st lock->ml.node); } } else { + status = DLM_NORMAL; dlm_lock_get(lock); list_add_tail(&lock->list, &res->blocked); kick_thread = 1;