GitHub pull request #3005 of commit 4e3eee72ad445e1772a0df89db6d54cbacd21ed9, no merge conflicts.sha1origin/pr/3005/mergeghprbActualCommit4e3eee72ad445e1772a0df89db6d54cbacd21ed9ghprbActualCommitAuthorghprbActualCommitAuthorEmailghprbAuthorRepoGitUrlhttps://github.com/netedwardwu/bcc.gitghprbTriggerAuthorghprbTriggerAuthorEmailghprbTriggerAuthorLoginyonghong-songghprbTriggerAuthorLoginMention@yonghong-songghprbPullId3005ghprbTargetBranchmasterghprbSourceBranchmasterGIT_BRANCHmasterghprbPullAuthorEmailghprbPullAuthorLoginnetedwardwughprbPullAuthorLoginMention@netedwardwughprbPullDescriptionGitHub pull request #3005 of commit 4e3eee72ad445e1772a0df89db6d54cbacd21ed9, no merge conflicts.ghprbPullTitlememleak: Add workaround to alleviate misjudgments when free is missingghprbPullLinkhttps://github.com/iovisor/bcc/pull/3005ghprbPullLongDescriptionProfiling in memory part is hard to be accurate because of BPF infrastructure.\r\nmemleak keeps misjudging memory leak on the complicated environment which has\r\nthe action of free in hard/soft irq.\r\n\r\nFor example, in my misjudged case:\r\n\r\n640 bytes in 10 allocations from stack\r\n--\r\n__kmalloc+0x178 [kernel]\r\n__kmalloc+0x178 [kernel]\r\nxhci_urb_enqueue+0x140 [kernel]\r\nusb_hcd_submit_urb+0x5e0 [kernel]\r\n\r\nThis result looks like kernel doesn't free urb_priv. However, it's not true.\r\nThe reason for this leak is because xhci hw irq interrupts during the BPF program.\r\nBPF program is not finished on that CPU, and xhci_irq() will call xhci_urb_free_priv()\r\nbefore the end. But the kernel doesn't permit this isr to go into BPF program again.\r\nBecause BPF infrastructure(trace_call_bpf) denied this action.\r\nSo we miss this free action and cause memory leak misjudgment.\r\n\r\nSide-effect:\r\n- Increase overhead for each memory allocation.\r\n- A higher chance to be interrupted at the allocation part causes ignore more allocations.\r\n\r\nThis workaround doesn't solve all misjudgments, the improvement in BPF infrastructure\r\nis the only solution.ghprbCommentBody[buildbot, test this please]ghprbGhRepositoryiovisor/bccghprbCredentialsId6d3daf13-69b8-48b1-9c8f-ec5353264113false<a title="memleak: Add workaround to alleviate misjudgments when free is missing" href="https://github.com/iovisor/bcc/pull/3005">PR #3005</a>: memleak: Add workaround to ...#59123643407460664bcc-pr #591591false5914729SUCCESS1594077096626https://buildbot.iovisor.org/jenkins/view/all/job/bcc-pr/591/git591https://buildbot.iovisor.org/jenkins/view/all/job/bcc-pr/label=fc25/591/591https://buildbot.iovisor.org/jenkins/view/all/job/bcc-pr/label=fc26/591/591https://buildbot.iovisor.org/jenkins/view/all/job/bcc-pr/label=fc27/591/591https://buildbot.iovisor.org/jenkins/view/all/job/bcc-pr/label=fc28/591/591https://buildbot.iovisor.org/jenkins/view/all/job/bcc-pr/label=ubuntu1604/591/591https://buildbot.iovisor.org/jenkins/view/all/job/bcc-pr/label=ubuntu1710/591/591https://buildbot.iovisor.org/jenkins/view/all/job/bcc-pr/label=ubuntu1804/591/