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[209.85.167.47]) by smtp.gmail.com with ESMTPSA id i19sm2647800lfj.17.2020.02.18.09.36.25 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 18 Feb 2020 09:36:25 -0800 (PST) Received: by mail-lf1-f47.google.com with SMTP id r14so15129647lfm.5 for ; Tue, 18 Feb 2020 09:36:25 -0800 (PST) X-Received: by 2002:a19:f514:: with SMTP id j20mr11135556lfb.31.1582047384649; Tue, 18 Feb 2020 09:36:24 -0800 (PST) MIME-Version: 1.0 References: <20200214154854.6746-1-sashal@kernel.org> <20200214154854.6746-542-sashal@kernel.org> In-Reply-To: From: Linus Torvalds Date: Tue, 18 Feb 2020 09:36:08 -0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH AUTOSEL 5.5 542/542] pipe: use exclusive waits when reading or writing To: Andrei Vagin Cc: LKML , Sasha Levin , stable , Josh Triplett , linux-fsdevel Content-Type: multipart/mixed; boundary="000000000000616ba8059edd1c62" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --000000000000616ba8059edd1c62 Content-Type: text/plain; charset="UTF-8" On Tue, Feb 18, 2020 at 1:51 AM Andrei Vagin wrote: > > This patch breaks one of CRIU tests. Here is a small reproducer: Good catch. > The quick fix looks like this: That one works, but is not really right. The things that change the number of readers or writers should simply use "wake_up_all()". I thought we did that already, but no - there _was_ one place where we did it, but that was for the pipe buffer size case, and in that case it's actually pointless. That case acts just like a "new space or data was added" So I think the right fix is the attached patch. Since you had such a lovely test-case, let me go test it too ;) Linus --000000000000616ba8059edd1c62 Content-Type: text/x-patch; charset="US-ASCII"; name="patch.diff" Content-Disposition: attachment; filename="patch.diff" Content-Transfer-Encoding: base64 Content-ID: X-Attachment-Id: f_k6s65iuv0 IGZzL3BpcGUuYyB8IDEwICsrKysrLS0tLS0KIDEgZmlsZSBjaGFuZ2VkLCA1IGluc2VydGlvbnMo KyksIDUgZGVsZXRpb25zKC0pCgpkaWZmIC0tZ2l0IGEvZnMvcGlwZS5jIGIvZnMvcGlwZS5jCmlu ZGV4IDVhMzRkNmMyMmQ0Yy4uNzZlN2Y2NmZlMmZlIDEwMDY0NAotLS0gYS9mcy9waXBlLmMKKysr IGIvZnMvcGlwZS5jCkBAIC0xMDI2LDggKzEwMjYsOCBAQCBzdGF0aWMgaW50IHdhaXRfZm9yX3Bh cnRuZXIoc3RydWN0IHBpcGVfaW5vZGVfaW5mbyAqcGlwZSwgdW5zaWduZWQgaW50ICpjbnQpCiAK IHN0YXRpYyB2b2lkIHdha2VfdXBfcGFydG5lcihzdHJ1Y3QgcGlwZV9pbm9kZV9pbmZvICpwaXBl KQogewotCXdha2VfdXBfaW50ZXJydXB0aWJsZSgmcGlwZS0+cmRfd2FpdCk7Ci0Jd2FrZV91cF9p bnRlcnJ1cHRpYmxlKCZwaXBlLT53cl93YWl0KTsKKwl3YWtlX3VwX2ludGVycnVwdGlibGVfYWxs KCZwaXBlLT5yZF93YWl0KTsKKwl3YWtlX3VwX2ludGVycnVwdGlibGVfYWxsKCZwaXBlLT53cl93 YWl0KTsKIH0KIAogc3RhdGljIGludCBmaWZvX29wZW4oc3RydWN0IGlub2RlICppbm9kZSwgc3Ry dWN0IGZpbGUgKmZpbHApCkBAIC0xMTQ0LDcgKzExNDQsNyBAQCBzdGF0aWMgaW50IGZpZm9fb3Bl bihzdHJ1Y3QgaW5vZGUgKmlub2RlLCBzdHJ1Y3QgZmlsZSAqZmlscCkKIAogZXJyX3dyOgogCWlm ICghLS1waXBlLT53cml0ZXJzKQotCQl3YWtlX3VwX2ludGVycnVwdGlibGUoJnBpcGUtPnJkX3dh aXQpOworCQl3YWtlX3VwX2ludGVycnVwdGlibGVfYWxsKCZwaXBlLT5yZF93YWl0KTsKIAlyZXQg PSAtRVJFU1RBUlRTWVM7CiAJZ290byBlcnI7CiAKQEAgLTEyNzEsOCArMTI3MSw4IEBAIHN0YXRp YyBsb25nIHBpcGVfc2V0X3NpemUoc3RydWN0IHBpcGVfaW5vZGVfaW5mbyAqcGlwZSwgdW5zaWdu ZWQgbG9uZyBhcmcpCiAJcGlwZS0+bWF4X3VzYWdlID0gbnJfc2xvdHM7CiAJcGlwZS0+dGFpbCA9 IHRhaWw7CiAJcGlwZS0+aGVhZCA9IGhlYWQ7Ci0Jd2FrZV91cF9pbnRlcnJ1cHRpYmxlX2FsbCgm cGlwZS0+cmRfd2FpdCk7Ci0Jd2FrZV91cF9pbnRlcnJ1cHRpYmxlX2FsbCgmcGlwZS0+d3Jfd2Fp dCk7CisJd2FrZV91cF9pbnRlcnJ1cHRpYmxlKCZwaXBlLT5yZF93YWl0KTsKKwl3YWtlX3VwX2lu dGVycnVwdGlibGUoJnBpcGUtPndyX3dhaXQpOwogCXJldHVybiBwaXBlLT5tYXhfdXNhZ2UgKiBQ QUdFX1NJWkU7CiAKIG91dF9yZXZlcnRfYWNjdDoK --000000000000616ba8059edd1c62--