Re: [PATCH v2 02/12] uprobes: correct mmap_sem locking assumptions in uprobe_write_opcode()
From: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Date: 2024-07-03 13:15:29
Also in:
bpf
On Mon, 1 Jul 2024 15:39:25 -0700 Andrii Nakryiko [off-list ref] wrote:
It seems like uprobe_write_opcode() doesn't require writer locked mmap_sem, any lock (reader or writer) should be sufficient. This was established in a discussion in [0] and looking through existing code seems to confirm that there is no need for write-locked mmap_sem. Fix the comment to state this clearly. [0] https://lore.kernel.org/linux-trace-kernel/20240625190748.GC14254@redhat.com/ (local) Fixes: 29dedee0e693 ("uprobes: Add mem_cgroup_charge_anon() into uprobe_write_opcode()")
nit: why this has Fixes but [01/12] doesn't? Should I pick both to fixes branch? Thank you,
quoted hunk ↗ jump to hunk
Signed-off-by: Andrii Nakryiko <andrii@kernel.org> --- kernel/events/uprobes.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 081821fd529a..f87049c08ee9 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c@@ -453,7 +453,7 @@ static int update_ref_ctr(struct uprobe *uprobe, struct mm_struct *mm, * @vaddr: the virtual address to store the opcode. * @opcode: opcode to be written at @vaddr. * - * Called with mm->mmap_lock held for write. + * Called with mm->mmap_lock held for read or write. * Return 0 (success) or a negative errno. */ int uprobe_write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm,-- 2.43.0
-- Masami Hiramatsu (Google) [off-list ref]