From: Oleg Nesterov <oleg@redhat.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: Anton Arapov <anton@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
linux-kernel@vger.kernel.org
Subject: [PATCH 3/9] uprobes: kill write_opcode()->lock_page(new_page)
Date: Fri, 13 Jul 2012 18:46:27 +0200 [thread overview]
Message-ID: <20120713164627.GA23545@redhat.com> (raw)
In-Reply-To: <20120713164552.GA23509@redhat.com>
write_opcode() does lock_page(new_page) for no reason. Nobody can
see this page until __replace_page() exposes it under ptl lock, and
we do nothing with this page after pte_unmap_unlock().
If nothing else, the similar code in do_wp_page() doesn't lock the
new page for page_add_new_anon_rmap/set_pte_at_notify.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar.vnet.ibm.com>
---
kernel/events/uprobes.c | 2 --
1 files changed, 0 insertions(+), 2 deletions(-)
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index fbb4188..dff8da2 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -239,9 +239,7 @@ retry:
if (ret)
goto unlock_out;
- lock_page(new_page);
ret = __replace_page(vma, vaddr, old_page, new_page);
- unlock_page(new_page);
unlock_out:
unlock_page(old_page);
--
1.5.5.1
next prev parent reply other threads:[~2012-07-13 16:51 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-13 16:45 [PATCH 0/9] uprobes: misc, resend Oleg Nesterov
2012-07-13 16:46 ` [PATCH 1/9] uprobes: don't recheck vma/f_mapping in write_opcode() Oleg Nesterov
2012-07-13 16:46 ` [PATCH 2/9] uprobes: __replace_page() should not use page_address_in_vma() Oleg Nesterov
2012-07-13 16:46 ` Oleg Nesterov [this message]
2012-07-13 16:46 ` [PATCH 4/9] uprobes: cleanup and document write_opcode()->lock_page(old_page) Oleg Nesterov
2012-07-13 16:46 ` [PATCH 5/9] uprobes: uprobe_mmap/munmap needs list_for_each_entry_safe() Oleg Nesterov
2012-07-13 16:46 ` [PATCH 6/9] uprobes: suppress uprobe_munmap() from mmput() Oleg Nesterov
2012-07-13 16:46 ` [PATCH 7/9] uprobes: fix overflow in vma_address/find_active_uprobe Oleg Nesterov
2012-07-13 16:46 ` [PATCH 8/9] uprobes: kill copy_vma()->uprobe_mmap() Oleg Nesterov
2012-07-13 16:46 ` [PATCH 9/9] uprobes: kill insert_vm_struct()->uprobe_mmap() Oleg Nesterov
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