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[172.10.233.147]) by smtp.gmail.com with ESMTPSA id i193-20020a0ddfca000000b00583d1fa1fccsm1332554ywe.0.2023.09.01.15.48.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 01 Sep 2023 15:48:35 -0700 (PDT) Date: Fri, 1 Sep 2023 15:48:26 -0700 (PDT) From: Hugh Dickins X-X-Sender: hugh@ripple.attlocal.net To: Mikhail Gavrilov cc: Hugh Dickins , Andrew Morton , Bagas Sanjaya , linux-kernel@vger.kernel.org, linux-mm@kvack.org, regressions@lists.linux.dev Subject: Re: 6.6/regression/bisected - after commit a349d72fd9efc87c8fd1d16d3164752d84a7275b system stopped booting In-Reply-To: Message-ID: <5e4d50d4-978-ce54-e1ae-40f7117dbf3d@google.com> References: <3548ca67-ce58-3bc6-fef5-348b98d7678b@google.com> <98eb1ba4-5bd3-ee7-1a88-47b054dc938@google.com> MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="-1463760895-45710664-1693608515=:22700" X-Rspam-User: X-Stat-Signature: rd7f4yf13e38puqpa41kw8w3pu5y9954 X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 734D914000E X-HE-Tag: 1693608517-463406 X-HE-Meta: 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 UwhaBzDh 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 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: This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. ---1463760895-45710664-1693608515=:22700 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE On Fri, 1 Sep 2023, Mikhail Gavrilov wrote: > On Fri, Sep 1, 2023 at 2:08=E2=80=AFPM Hugh Dickins wr= ote: > > > > > > Sorry about that, please try this instead, adds EXPORT_SYMBOL(pte_unmap= ). > > >=20 > Thanks, now I have a working kernel builded at commit a349d72fd9ef. >=20 > > I've never used stackdepot before, but I've tried this out in good and > > bad cases, and expect it to work for you, shedding light on where is > > going wrong - machine should boot up fine, and in dmesg you'll find one > > stacktrace between "WARNING: pte_map..." and "End of pte_map..." lines. >=20 > Interesting, I checked twice but I didn't find any entry with > "pte_map" in the kernel log after applying your patch. That was very disappointing: I found it hard to explain, but was thinking of sending you a similar patch, doing the same check on all your 32 CPUs - maybe the stall being on CPU 0 in your photo was accidental. But now I think I have the shameful answer (which studying your dmesg, and the 82328 jiffies at 86 seconds in your photo, did help me towards). That mm/pagewalk fix I put into 6.5 has a grievous oversight (and a video of your failing 6.6 bootup would likely have shown a WARN_ON_ONCE from the underflow in __rcu_read_unlock()). Please revert the debug patch I sent yesterday (or earlier today), please try booting with this one on top of a349d72fd9ef; and if that's successful, then please go back to your original Rawhide tree and apply this on top of that, to confirm that boots to a working system too - thanks. With my apologies, [PATCH] mm/pagewalk: fix bootstopping regression from extra pte_unmap() [ Commit message yet to be written: it's actually something to go to 6.5 stable, to correct i386 CONFIG_HIGHPTE there - though we know of no case where it is actually hit. ] Signed-off-by: Hugh Dickins --- mm/pagewalk.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/pagewalk.c b/mm/pagewalk.c index 2022333805d3..9e7d0276c38a 100644 --- a/mm/pagewalk.c +++ b/mm/pagewalk.c @@ -58,7 +58,7 @@ static int walk_pte_range(pmd_t *pmd, unsigned long addr,= unsigned long end, =09=09=09pte =3D pte_offset_map(pmd, addr); =09=09if (pte) { =09=09=09err =3D walk_pte_range_inner(pte, addr, end, walk); -=09=09=09if (walk->mm !=3D &init_mm) +=09=09=09if (walk->mm !=3D &init_mm && addr < TASK_SIZE) =09=09=09=09pte_unmap(pte); =09=09} =09} else { --=20 2.35.3 ---1463760895-45710664-1693608515=:22700--