From patchwork Tue Oct 1 22:52:05 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrii Nakryiko X-Patchwork-Id: 13818826 X-Patchwork-Delegate: bpf@iogearbox.net Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9902D1CF5FE; Tue, 1 Oct 2024 22:52:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727823145; cv=none; b=T15Jjza1kzE2iIhW1rgFyJhDsNxgWvoRaH2C1hd4wbNWvT5qu/Kh9IG+ew4uQYn5JP7+eEZaNUwYpHyntlcoGgaFYPIEdUIQTuaLrFxWx/17VtVGNCHBMhfag0r0Mek4URR0Fd7t/feyzKRTIY76p3+Rx8as29yizKQp5nsr+Hw= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727823145; c=relaxed/simple; bh=Fe0W0B2s6ceCb71LS5xDyOWx4mAiBCLoZvDtud5NppM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=OTYqxHOMkGj5C5o4JIvvWEpHaSDr6M4L7CQu0xoMXLf1rjJW2kMd0iAfNxY8SD5YdabnNQs+ixmQC4LcR+kYQ1hvOizke9zQ1ry4l8KOmD7OKgqYW8NKgRjdAt+flodBjZaYVp4CCxmjtIrkARBkgElLdreRuRE76uegWWU99o0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=CpHdhX2M; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="CpHdhX2M" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4533DC4CEC6; Tue, 1 Oct 2024 22:52:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1727823145; bh=Fe0W0B2s6ceCb71LS5xDyOWx4mAiBCLoZvDtud5NppM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=CpHdhX2My8bEMExNjtkiCBGzgD/icJoKKBqYiIrUbPzCTfYszjoLtbMmq1dssYj3T Vrwe8b43Ff5XJWhkflBzoIkA4mbw1tW1bc+gdwJ5gHBcaUuGvSIZVtObiyY9gzB6fL 279sn7GDirJgGJM+LjoW+rAaFbP+0qgSw780RGYXJSzkxUeqFy2lbgEVIGwSB2x2EA yVmzNitaw7bjQ8Gxrp5it9ifxi0NkWH3rkKE5gjhUNhD8GF3nt6umR84JDzYdOvj6S 032wn+XUSq9IQVRDNOwPE/ysqQ+e7s8s7xRGN/F99dVabaYTJU5jAaQ7kjjhMvZGTm 9/45fjGcrlZ7g== From: Andrii Nakryiko To: linux-trace-kernel@vger.kernel.org, peterz@infradead.org, oleg@redhat.com Cc: rostedt@goodmis.org, mhiramat@kernel.org, bpf@vger.kernel.org, linux-kernel@vger.kernel.org, jolsa@kernel.org, paulmck@kernel.org, willy@infradead.org, surenb@google.com, akpm@linux-foundation.org, linux-mm@kvack.org, mjguzik@gmail.com, brauner@kernel.org, jannh@google.com, mhocko@kernel.org, vbabka@suse.cz, mingo@kernel.org, Andrii Nakryiko , Amir Goldstein Subject: [PATCH v2 tip/perf/core 3/5] fs: add back RCU-delayed freeing of FMODE_BACKING file Date: Tue, 1 Oct 2024 15:52:05 -0700 Message-ID: <20241001225207.2215639-4-andrii@kernel.org> X-Mailer: git-send-email 2.43.5 In-Reply-To: <20241001225207.2215639-1-andrii@kernel.org> References: <20241001225207.2215639-1-andrii@kernel.org> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 6cf41fcfe099 ("backing file: free directly") switched FMODE_BACKING files to direct freeing as back then there were no use cases requiring RCU protected access to such files. Now, with speculative lockless VMA-to-uprobe lookup logic, we do need to have a guarantee that struct file memory is not going to be freed from under us during speculative check. So add back RCU-delayed freeing logic. We use headless kfree_rcu_mightsleep() variant, as file_free() is only called for FMODE_BACKING files in might_sleep() context. Suggested-by: Suren Baghdasaryan Cc: Christian Brauner Cc: Amir Goldstein Signed-off-by: Andrii Nakryiko Reviewed-by: Christian Brauner --- fs/file_table.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/file_table.c b/fs/file_table.c index ca7843dde56d..257691d358ee 100644 --- a/fs/file_table.c +++ b/fs/file_table.c @@ -68,7 +68,7 @@ static inline void file_free(struct file *f) put_cred(f->f_cred); if (unlikely(f->f_mode & FMODE_BACKING)) { path_put(backing_file_user_path(f)); - kfree(backing_file(f)); + kfree_rcu_mightsleep(backing_file(f)); } else { kmem_cache_free(filp_cachep, f); }