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b=uYjmXJ0o0nclaaJYRmGvcWh+PMXoFy/4V5w+QgCWh8eiWJb/86f00TXFVBhbrLHhB 8lQosBwA0un/NICBloB17fuu/r+IR/E6r6IhUBF68l7qps2RaUPak5VGjmfyDXCX/Q bRnygD5L99ynxU0xzCPn1/M1i0SWw9TtVfU7HRFk= Date: Thu, 27 Aug 2026 15:58:27 -0700 From: Andrew Morton To: Wilson Felipe Pereira Cc: Johannes Weiner , Yosry Ahmed , Nhat Pham , Chengming Zhou , Tejun Heo , =?ISO-8859-1?Q?"Michal_Koutn=FD"?= , Shuah Khan , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 0/2] selftests/cgroup: fixes for test_zswap on single core VM Message-Id: <20260827155827.e40d5d88cee174437a16f432@linux-foundation.org> In-Reply-To: <20260827034807.2822234-1-wfelipe@google.com> References: <20260827034807.2822234-1-wfelipe@google.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Stat-Signature: gda89ne98rtjkcsyiafmmbp1j11gesxz X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 5BCB840007 X-Rspam-User: X-HE-Tag: 1787871509-110355 X-HE-Meta: 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 YUTau2AE AtklCreS85uNZEmKNy2S0zKdoYha5JdWON2ZtMubu1uzgG0LFNWMQ5Ghh1EJW/pBNTXo757F7yyBsiblgyxwlK0U8E9NzDQJriQQcpElse0S8TlP3CFRF2XVo5y4t/c4laeyLYKq9UglunlvaLSYzUzPezGLDw5DrO1RwhHoqVsi/d2XY3NWf2wudqmxWne2m60Q8407+nFACErFBKwH31QgOcve1O9+crYTeIFl1ktcDlkeHFVndIN8sBsyWlC3z72v1y2zQGSz3ndbW+iEb5ihJrr3ORo1S/jPILN89eqORzyEJt0WUuyB75+jsQEwnbZsVpRhtk49ZZnmOfSe64/J11J/CFTVYOJBKOqXEqGzj2TYdtvX+Jp9IE2sBKEUhTK74 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, 27 Aug 2026 03:47:40 +0000 Wilson Felipe Pereira wrote: > This series fixes two test failures in test_zswap observed when running on > a single-core VM (-smp 1) with 4GB of RAM. > > Patch 1 addresses a race condition in test_zswap_writeback() where > waitpid() returns before the exiting child process is switched away by the > kernel, causing an immediate write of "+memory" to cgroup.subtree_control > to fail with -EBUSY. We fix this by waiting for cgroup.events to report > "populated 0". > > Patch 2 fixes an implicit unsigned conversion bug in test_no_kmem_bypass() > where small negative timing differences between debugfs stored_pages and > cgroup zswapped bytes caused the comparison to falsely fail due to > unsigned promotion. Thanks. Sashiko thinks there remain some signedness/truncation/overflow issues in there: https://sashiko.dev/#/patchset/20260827034807.2822234-1-wfelipe@google.com