From patchwork Fri May 8 15:55:24 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Joel Brobecker X-Patchwork-Id: 6632 Received: (qmail 70497 invoked by alias); 8 May 2015 15:55:37 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Delivered-To: mailing list gdb-patches@sourceware.org Received: (qmail 70487 invoked by uid 89); 8 May 2015 15:55:37 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.7 required=5.0 tests=AWL, BAYES_00, SPF_PASS, T_RP_MATCHES_RCVD autolearn=ham version=3.3.2 X-HELO: rock.gnat.com Received: from rock.gnat.com (HELO rock.gnat.com) (205.232.38.15) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES256-SHA encrypted) ESMTPS; Fri, 08 May 2015 15:55:36 +0000 Received: from localhost (localhost.localdomain [127.0.0.1]) by filtered-rock.gnat.com (Postfix) with ESMTP id CDD74287DD for ; Fri, 8 May 2015 11:55:34 -0400 (EDT) Received: from rock.gnat.com ([127.0.0.1]) by localhost (rock.gnat.com [127.0.0.1]) (amavisd-new, port 10024) with LMTP id Bqkgovw++wrL for ; Fri, 8 May 2015 11:55:34 -0400 (EDT) Received: from joel.gnat.com (localhost.localdomain [127.0.0.1]) by rock.gnat.com (Postfix) with ESMTP id A0B9128790 for ; Fri, 8 May 2015 11:55:34 -0400 (EDT) Received: by joel.gnat.com (Postfix, from userid 1000) id 27E7840DAA; Fri, 8 May 2015 08:55:34 -0700 (PDT) From: Joel Brobecker To: gdb-patches@sourceware.org Subject: [RFA/commit] Memory leak in on reading frame register Date: Fri, 8 May 2015 08:55:24 -0700 Message-Id: <1431100524-7793-1-git-send-email-brobecker@adacore.com> [On behalf of Jerome Guitton] When using a conditional breakpoint where the condition evaluated to false a large number of times before the program stopped, a user reported that GDB's memory consumption was growing very quickly until it ran out of memory. The problem was tracked down to temporary struct values being created each time the program stops and we evaluate those conditions. This patch fixes the issue by releasing the temporary values, and adds a comment explaining why we do that. gdb/ChangeLog: Jerome Guitton : * findvar.c (read_frame_register_value): Fix a memory leak. Tested on x86_64-linux. No regression. I'll push the patch in a week or so, pending comments. Thanks, diff --git a/gdb/findvar.c b/gdb/findvar.c index 2079b4b..8ccf267 100644 --- a/gdb/findvar.c +++ b/gdb/findvar.c @@ -686,6 +686,17 @@ read_frame_register_value (struct value *value, struct frame_info *frame) value_contents_copy (value, offset, regval, reg_offset, reg_len); + /* Release regval right away, as we know we do not need it anymore. + Otherwise, those values just keep accumulating until they finally + get released when the current command finishes (as part of the + all_values chain cleanup). While this works most of the time, + we have observed that, when using a conditional breakpoint where + the condition gets repeatedly evaluated to false, keeping those + values in memory causes a rapid and measurable growth in memory + consumption, eventually leading us to running out of memory. */ + release_value (regval); + value_free (regval); + offset += reg_len; len -= reg_len; reg_offset = 0;