From: Song Liu <songliubrav...@fb.com> Caller of uprobe_register is required to keep the inode and containing mount point referenced.
There was misuse of igrab() in uprobes.c and trace_uprobe.c. This is because igrab() will not prevent umount of the containing mount point. To fix this, we added path to struct trace_uprobe, which keeps the inode and containing mount reference. For uprobes.c, it is not necessary to call igrab() in uprobe_register(), as the caller is required to keep the inode reference. The igrab() is removed and comments on this requirement is added to uprobe_register(). Link: http://lkml.kernel.org/r/CAELBmZB2XX=qeoladvgg4cpx4gentcsnwqqujluk1ongrj3...@mail.gmail.com Link: http://lkml.kernel.org/r/20180423172135.4050588-2-songliubrav...@fb.com Cc: Ingo Molnar <mi...@redhat.com> Cc: Howard McLauchlan <hmclauch...@fb.com> Cc: Josef Bacik <jba...@fb.com> Cc: Srikar Dronamraju <sri...@linux.vnet.ibm.com> Acked-by: Miklos Szeredi <mszer...@redhat.com> Signed-off-by: Song Liu <songliubrav...@fb.com> Signed-off-by: Steven Rostedt (VMware) <rost...@goodmis.org> --- kernel/events/uprobes.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index ce6848e46e94..1725b902983f 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -491,7 +491,7 @@ static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset) if (!uprobe) return NULL; - uprobe->inode = igrab(inode); + uprobe->inode = inode; uprobe->offset = offset; init_rwsem(&uprobe->register_rwsem); init_rwsem(&uprobe->consumer_rwsem); @@ -502,7 +502,6 @@ static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset) if (cur_uprobe) { kfree(uprobe); uprobe = cur_uprobe; - iput(inode); } return uprobe; @@ -701,7 +700,6 @@ static void delete_uprobe(struct uprobe *uprobe) rb_erase(&uprobe->rb_node, &uprobes_tree); spin_unlock(&uprobes_treelock); RB_CLEAR_NODE(&uprobe->rb_node); /* for uprobe_is_active() */ - iput(uprobe->inode); put_uprobe(uprobe); } @@ -873,7 +871,8 @@ static void __uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *u * tuple). Creation refcount stops uprobe_unregister from freeing the * @uprobe even before the register operation is complete. Creation * refcount is released when the last @uc for the @uprobe - * unregisters. + * unregisters. Caller of uprobe_register() is required to keep @inode + * (and the containing mount) referenced. * * Return errno if it cannot successully install probes * else return 0 (success) -- 2.17.0
