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b=XH97yrqlqW9680GKgc4K9WvLNVabunnNtw6rQYsqPH91xIeL7Z7d4PxLbPvUbyv0E ksl92UZaozw0dst3Pt3Poq7XeAd3UcbsuPfVuomLzJS16NQydbeLwM/ahGUgrAICTj +YaWlu0kKSq+05dJlFctlKjThXhPvglEOOAUW9U0eY/MJqIapFOVitZeZXyPcJQfXE sRG9oh6ZKMajnuDxEpI4HWMWQ3VoOYeLrkbCzIJY/lx8OB5FzebLTb4KPY3Pl72Tyv 36ef6arjoqZ4RaPZGU7bLlGGms3Ni73RabSv4TAXq/dlJo1CxvK3U1kjniQiTS1zLv L7jSoV84wcUbg== Date: Tue, 15 Sep 2026 15:19:56 +0100 From: Harry Yoo To: SJ Park Cc: Johannes Weiner , Yosry Ahmed , Nhat Pham , Usama Arif , Chengming Zhou , Tejun Heo , Michal =?utf-8?Q?Koutn=C3=BD?= , Shuah Khan , Andrew Morton , Joshua Hahn , Kiryl Shutsemau , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] selftests/cgroup: ignore memory.reclaim -EAGAIN for zswap writeback test Message-ID: References: <20260915141049.70696-1-sj@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260915141049.70696-1-sj@kernel.org> X-Rspamd-Server: rspam04 X-Rspam-User: X-Stat-Signature: 9afoxh83gqpfyhkgfa7s811k9z8ctynx X-Rspamd-Queue-Id: 3144C140003 X-HE-Tag: 1789481999-379382 X-HE-Meta: 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 7pHdmss6 AiebS3g3x1UFCXgfM/BxhhMTyHu2JcnR8eS+6akPRWaZn8ie7u0o977UUtTfW7Qrlr4uFBk+HIgdGgJJsiSUyol6itax69WRZUCa20TLVM0gDtXfUjUJ6/iZt8kgQ9yQU/fxppePLQP3XjZnR5+vSfeJQjJPotChVH1nmEOBG7QbzSmxnpaJSZdXKy28rFzPTZqspspNibVhNSwjl7aO3OW5iY2FKq2AzukNfLH+SSRQ6wi/toMRsj62cyz1gl4KUMPwIDKO5hqpq3Qik+QMzp5R9P13qaTq6gEFrY+3gZjB3HpEZXpmQaFwM7w6OtCCdgynf6nOQ/AAWQlctgZ15Lxb4MZ6NRm5hZ8C8 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Sep 15, 2026 at 07:10:48AM -0700, SJ Park wrote: > On Tue, 15 Sep 2026 11:21:53 +0100 Harry Yoo wrote: > > > On Mon, Sep 14, 2026 at 05:18:17PM -0700, SJ Park wrote: > > > On Mon, 14 Sep 2026 21:36:39 +0100 "Harry Yoo (Meta)" wrote: > > > > --- a/tools/testing/selftests/cgroup/test_zswap.c > > > > +++ b/tools/testing/selftests/cgroup/test_zswap.c > > > > @@ -346,7 +346,16 @@ static int attempt_writeback(const char *cgroup, void *arg) > > > > * it can't writeback to swap. > > > > */ > > > > ret = cg_write_numeric(cgroup, "memory.reclaim", memsize); > > > > - if (!wb_enabled) > > > > + > > > > + /* > > > > + * When writeback is enabled, memory.reclaim may still fail to reclaim > > > > + * the requested amount of memory due to a slow swap device. > > > > + * Ignore -EAGAIN here. The caller determines pass/fail based on the > > > > + * zswap writeback counter. > > > > + */ > > > > + if (wb_enabled && ret == -EAGAIN) > > > > + ret = 0; > > > > + else if (!wb_enabled) > > > > ret = (ret == -EAGAIN) ? 0 : -1; > > > > > > My humble eyes were unable to easily understand the change. Is the change > > > effectively same to below, and if so, would this be easier to read? > > > > > > ''' > > > @@ -344,10 +344,11 @@ static int attempt_writeback(const char *cgroup, void *arg) > > > * writeback as zswap.max is 1/4 of what was needed when reclaim ran the first time. > > > * If writeback is disabled, memory reclaim will fail as zswap is limited and > > > * it can't writeback to swap. > > > + * Even if writeback is enabled, it could return -EAGAIN due to a slow > > > + * swap device. > > > */ > > > ret = cg_write_numeric(cgroup, "memory.reclaim", memsize); > > > - if (!wb_enabled) > > > - ret = (ret == -EAGAIN) ? 0 : -1; > > > + ret = (ret == -EAGAIN) ? 0 : -1; > > > > Hmm, no. This will mark the test as failed when a write to > > memory.reclaim returns zero even when wb_enabled is true. > > > > It's not the same because when wb_enabled == true we consider > > ret == 0 or ret == -EAGAIN as success, while with wb_enabled == false > > we consider ret == -EAGAIN as success. > > Ah, got it. You are right. Sorry for making noise and thank you for kindly > correcting me. No worries ;-) > Reviewed-by: SJ Park Thanks a lot for reviewing, SJ! -- Cheers, Harry / Hyeonggon