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Mon, 11 Jan 2021 09:16:50 +0000 (UTC) Date: Mon, 11 Jan 2021 10:16:46 +0100 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1610356608; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=LEXe/B0Q3kSQ+pyi11QVzunFEXSDJfyzRctZD/mSGwY=; b=uCnnwbctZA1rQ3V0p2kZu+d3zaZFHTKUJPOo76b5D7cuxWEOXVJdpIqiLFP5aTXpvIjv9s qwAvW5WhwffRTnvcztEi2+1v/oENxwE79UOubMC7jJKeubOBD6zsvQUL74GztGQIAKB8HO BT4sxjhTakFs4dVqAQh6GY6Sn14JBtplCvPA2cmstH/p72FEB2TnSYVyeSL8sjTNI80v3T oCsDUl6wYJXQ9QueQxoB6wuP+fNUTobWuAtyizRQCOtZthAqYs4ojlXRNfsr2J83hANEKU KrLFmoV7Ai9vVG4RtXD3Lh/qUjXo6jULZnNtu/UYw3EhRXUZtNRGRg4NMuxugQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1610356608; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=LEXe/B0Q3kSQ+pyi11QVzunFEXSDJfyzRctZD/mSGwY=; b=aQ0P+BB77W0OA8uLsIQDcnYrwKkOka8jvG0VLRGl2/Wpm04Edp57/CM7syBgLiKrsJkDcC 9SLKzMSTP9RzBiAw== From: Sebastian Andrzej Siewior To: Thomas Bogendoerfer Cc: Paul Cercueil , tglx@linutronix.de, airlied@linux.ie, airlied@redhat.com, akpm@linux-foundation.org, arnd@arndb.de, bcrl@kvack.org, bristot@redhat.com, bsegall@google.com, bskeggs@redhat.com, chris@zankel.net, christian.koenig@amd.com, clm@fb.com, davem@davemloft.net, deanbo422@gmail.com, dietmar.eggemann@arm.com, dri-devel@lists.freedesktop.org, dsterba@suse.com, green.hu@gmail.com, hch@lst.de, intel-gfx@lists.freedesktop.org, jcmvbkbc@gmail.com, josef@toxicpanda.com, juri.lelli@redhat.com, kraxel@redhat.com, linux-aio@kvack.org, linux-arm-kernel@lists.infradead.org, linux-btrfs@vger.kernel.org, linux-csky@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-graphics-maintainer@vmware.com, linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org, linux-mm@kvack.org, linux-snps-arc@lists.infradead.org, linux-xtensa@linux-xtensa.org, linux@armlinux.org.uk, linuxppc-dev@lists.ozlabs.org, mgorman@suse.de, mingo@kernel.org, monstr@monstr.eu, mpe@ellerman.id.au, nickhu@andestech.com, nouveau@lists.freedesktop.org, paulmck@kernel.org, paulus@samba.org, peterz@infradead.org, ray.huang@amd.com, rodrigo.vivi@intel.com, rostedt@goodmis.org, sparclinux@vger.kernel.org, spice-devel@lists.freedesktop.org, sroland@vmware.com, torvalds@linuxfoundation.org, vgupta@synopsys.com, vincent.guittot@linaro.org, viro@zeniv.linux.org.uk, virtualization@lists.linux-foundation.org, x86@kernel.org Subject: Re: [patch V3 13/37] mips/mm/highmem: Switch to generic kmap atomic Message-ID: <20210111091646.hkugbtlcced3vmno@linutronix.de> References: <20210108235805.GA17543@alpha.franken.de> <20210109003352.GA18102@alpha.franken.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20210109003352.GA18102@alpha.franken.de> 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: On 2021-01-09 01:33:52 [+0100], Thomas Bogendoerfer wrote: > On Sat, Jan 09, 2021 at 12:58:05AM +0100, Thomas Bogendoerfer wrote: > > On Fri, Jan 08, 2021 at 08:20:43PM +0000, Paul Cercueil wrote: > > > Hi Thomas, > > > > > > 5.11 does not boot anymore on Ingenic SoCs, I bisected it to this commit. > > > > > > Any idea what could be happening? > > > > not yet, kernel crash log of a Malta QEMU is below. > > update: > > This dirty hack lets the Malta QEMU boot again: > > diff --git a/mm/highmem.c b/mm/highmem.c > index c3a9ea7875ef..190cdda1149d 100644 > --- a/mm/highmem.c > +++ b/mm/highmem.c > @@ -515,7 +515,7 @@ void *__kmap_local_pfn_prot(unsigned long pfn, pgprot_t prot) > vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx); > BUG_ON(!pte_none(*(kmap_pte - idx))); > pteval = pfn_pte(pfn, prot); > - set_pte_at(&init_mm, vaddr, kmap_pte - idx, pteval); > + set_pte(kmap_pte - idx, pteval); > arch_kmap_local_post_map(vaddr, pteval); > current->kmap_ctrl.pteval[kmap_local_idx()] = pteval; > preempt_enable(); > > set_pte_at() tries to update cache and could do an kmap_atomic() there. So the old implementation used set_pte() while the new one uses set_pte_at(). > Not sure, if this is allowed at this point. The problem is the recursion kmap_atomic() -> __update_cache() -> kmap_atomic() and kmap_local_idx_push() runs out if index space before stack space. I'm not sure if the __update_cache() worked for highmem. It has been added for that in commit f4281bba81810 ("MIPS: Handle highmem pages in __update_cache") but it assumes that the address returned by kmap_atomic() is the same or related enough for flush_data_cache_page() to work. > Thomas. > Sebastian