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AJvYcCWLQJluGYj0r7FQmyWafqPCmOl1zsdOJkv+7CN4/L9Xj3MNyQDFmbZubFA0abrj+c/PHIWACFJkOg==@kvack.org X-Gm-Message-State: AOJu0YzgqyT3erF/XGq6CGvtp3wrReXwmb70YUDhapVaN7iO4kEsmdHt MCOgafM+VoFK6CWV635FjK3/jbjAjA9RibWwh98b+g3DpROw3EeJrkDfyX38y77rrXrEdyrlCFu UsjcGyB/o+A7ZW8Vp7Nc7jQ98HZmyMzvjJ1vv2smEzhXDYOXjtlOqJ5Gh X-Gm-Gg: ASbGncuHCkK3/cJfToPrfIlzM7aXxFx161TGHgD9QD58K3mRDWlV/zkMczApdDH+pml Swnr8aLs5Xv3ZXZGLXyfyROwZFGY6Xzec/B9lglFoUIRpIfrmsAdbpk1j5mcNVkM5zFehM8x5Cd guBJwfePGIVEzHwEo56O1mm3GIPRnagmvnu055WtnknwKMh5oqTUSyoy6Lvqi0ZFVXhEO3 X-Google-Smtp-Source: AGHT+IGmqJYRWpHfBs4knSYJUFVbh1DAaRw+ESFOCzSooRHccflCMCRz1LdjC7qSsxMz153KQSQCp/XS2qj8YR06dWE= X-Received: by 2002:a05:622a:8350:b0:471:f34d:1d83 with SMTP id d75a77b69052e-4a7fc92afa7mr486231cf.7.1750959176797; Thu, 26 Jun 2025 10:32:56 -0700 (PDT) MIME-Version: 1.0 References: <20250620150058.1729489-1-peterx@redhat.com> In-Reply-To: <20250620150058.1729489-1-peterx@redhat.com> From: Axel Rasmussen Date: Thu, 26 Jun 2025 10:32:20 -0700 X-Gm-Features: Ac12FXx7563rh1P_h_xeJbXZuYH1OOwammAUarvbQ_QgtPaZvjNtcCFVbDfAWaU Message-ID: Subject: Re: [PATCH] selftests/mm: Reduce uffd-unit-test poison test to minimum To: Peter Xu Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , Ujwal Kundur , David Hildenbrand , shuah@kernel.org, jackmanb@google.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam11 X-Rspam-User: X-Rspamd-Queue-Id: 20376140011 X-Stat-Signature: sndrzicipbakpyjgjmn4mkrhecpupsom X-HE-Tag: 1750959177-624960 X-HE-Meta: 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 i1Y6W/aT 7anMy3y878IQs8WVeWQIqQXcqpjmkHxuiJr7MtZUrdUcix+WmlCu90zu270b+Mt0v020LRj1K7pcU/1pzU14KDVcAq5XfNA3AAHl7gqGQufpOWrZjWn6/66S4H+njcoYEA5Rz1bMo2DL4l8dixXxb3HKeeULw4PTpABmSDHe1Nkq4lb5afehAXUEZ55Ag/mZ23cd40ydDDvt5Cu+1TcIY9eFM/SaRwAbbHLRzz2tc2odWyFAKqS+xDfQlUiD66aA/evdbFhc8IlytwjO8DtjHm8Cgy2L81f39PVkdl23Zz1ORzQ8Nk5K7TrZLZw== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Jun 20, 2025 at 8:01=E2=80=AFAM Peter Xu wrote: > > The test will still generate quite some unwanted MCE error messages to > syslog. There was old proposal ratelimiting the MCE messages from kernel= , > but that has risk of hiding real useful information on production systems= . > > We can at least reduce the test to minimum to not over-pollute dmesg, > however trying to not lose its coverage too much. > > Cc: Axel Rasmussen > Signed-off-by: Peter Xu Besides a small nitpick you can take: Reviewed-by: Axel Rasmussen Making the functional tests small makes sense to me, especially for poisoning. Only reason to use a huge number of pages is if we're trying to stress racy bugs or so, but really for that you'd want even more pages / more threads / run for a longer time. It makes sense to separate that use case out / maybe not run it by default, and leave the functional tests small + fast. > --- > tools/testing/selftests/mm/uffd-unit-tests.c | 20 ++++++++++++++------ > 1 file changed, 14 insertions(+), 6 deletions(-) > > diff --git a/tools/testing/selftests/mm/uffd-unit-tests.c b/tools/testing= /selftests/mm/uffd-unit-tests.c > index c73fd5d455c8..39b3fd1b7bf2 100644 > --- a/tools/testing/selftests/mm/uffd-unit-tests.c > +++ b/tools/testing/selftests/mm/uffd-unit-tests.c > @@ -1027,6 +1027,9 @@ static void uffd_poison_handle_fault( > do_uffdio_poison(uffd, offset); > } > > +/* Make sure to cover odd/even, and minimum duplications */ > +#define UFFD_POISON_TEST_NPAGES 4 > + > static void uffd_poison_test(uffd_test_args_t *targs) > { > pthread_t uffd_mon; > @@ -1034,12 +1037,17 @@ static void uffd_poison_test(uffd_test_args_t *ta= rgs) > struct uffd_args args =3D { 0 }; > struct sigaction act =3D { 0 }; > unsigned long nr_sigbus =3D 0; > - unsigned long nr; > + unsigned long nr, poison_pages =3D UFFD_POISON_TEST_NPAGES; > + > + if (nr_pages < poison_pages) { > + uffd_test_skip("Too less pages for POISON test"); I think "Too few pages for POISON test" is more grammatically correct. > + return; > + } > > fcntl(uffd, F_SETFL, uffd_flags | O_NONBLOCK); > > - uffd_register_poison(uffd, area_dst, nr_pages * page_size); > - memset(area_src, 0, nr_pages * page_size); > + uffd_register_poison(uffd, area_dst, poison_pages * page_size); > + memset(area_src, 0, poison_pages * page_size); > > args.handle_fault =3D uffd_poison_handle_fault; > if (pthread_create(&uffd_mon, NULL, uffd_poll_thread, &args)) > @@ -1051,7 +1059,7 @@ static void uffd_poison_test(uffd_test_args_t *targ= s) > if (sigaction(SIGBUS, &act, 0)) > err("sigaction"); > > - for (nr =3D 0; nr < nr_pages; ++nr) { > + for (nr =3D 0; nr < poison_pages; ++nr) { > unsigned long offset =3D nr * page_size; > const char *bytes =3D (const char *) area_dst + offset; > const char *i; > @@ -1078,9 +1086,9 @@ static void uffd_poison_test(uffd_test_args_t *targ= s) > if (pthread_join(uffd_mon, NULL)) > err("pthread_join()"); > > - if (nr_sigbus !=3D nr_pages / 2) > + if (nr_sigbus !=3D poison_pages / 2) > err("expected to receive %lu SIGBUS, actually received %l= u", > - nr_pages / 2, nr_sigbus); > + poison_pages / 2, nr_sigbus); > > uffd_test_pass(); > } > -- > 2.49.0 >