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[82.17.115.212]) by smtp.gmail.com with ESMTPSA id f14sm4508599wri.16.2021.06.17.02.22.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 17 Jun 2021 02:22:50 -0700 (PDT) Date: Thu, 17 Jun 2021 10:22:49 +0100 From: Aaron Tomlin To: Georgi Djakov Cc: vbabka@suse.cz, akpm@linux-foundation.org, iamjoonsoo.kim@lge.com, rientjes@google.com, penberg@kernel.org, cl@linux.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, djakov@kernel.org Subject: Re: [PATCH] mm/slub: Add taint after the errors are printed Message-ID: <20210617092249.5v6kh3q6skawkae6@ava.usersys.com> X-PGP-Key: http://pgp.mit.edu/pks/lookup?search=atomlin%40redhat.com X-PGP-Fingerprint: 7906 84EB FA8A 9638 8D1E 6E9B E2DE 9658 19CC 77D6 References: <1623860738-146761-1-git-send-email-quic_c_gdjako@quicinc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <1623860738-146761-1-git-send-email-quic_c_gdjako@quicinc.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 2021-06-16 09:25 -0700, Georgi Djakov wrote: > When running the kernel with panic_on_taint, the usual slub debug error > messages are not being printed when object corruption happens. That's > because we panic in add_taint(), which is called before printing the > additional information. This is a bit unfortunate as the error messages > are actually very useful, especially before a panic. Let's fix this by > moving add_taint() after the errors are printed on the console. > > Signed-off-by: Georgi Djakov > --- > mm/slub.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/mm/slub.c b/mm/slub.c > index a8b0daa1a307..ce7b8e4551b5 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -719,8 +719,6 @@ static void slab_bug(struct kmem_cache *s, char *fmt, ...) > pr_err("=============================================================================\n"); > pr_err("BUG %s (%s): %pV\n", s->name, print_tainted(), &vaf); > pr_err("-----------------------------------------------------------------------------\n\n"); > - > - add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); > va_end(args); > } > > @@ -801,6 +799,7 @@ void object_err(struct kmem_cache *s, struct page *page, > > slab_bug(s, "%s", reason); > print_trailer(s, page, object); > + add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); > } > > static __printf(3, 4) void slab_err(struct kmem_cache *s, struct page *page, > @@ -818,6 +817,7 @@ static __printf(3, 4) void slab_err(struct kmem_cache *s, struct page *page, > slab_bug(s, "%s", buf); > print_page_info(page); > dump_stack(); > + add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); > } > > static void init_object(struct kmem_cache *s, void *object, u8 val) > @@ -869,6 +869,7 @@ static int check_bytes_and_report(struct kmem_cache *s, struct page *page, > fault, end - 1, fault - addr, > fault[0], value); > print_trailer(s, page, object); > + add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); > > skip_bug_print: > restore_bytes(s, what, value, fault, end); > Good catch. Thanks! Reviewed-by: Aaron Tomlin -- Aaron Tomlin