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b=TDmI5TZZjn/npyMlYJoum+PjSv5HtAVaOgXRweFZGSwsSMdDI/CQ7BzLDG7vT4jHs 1iFdFoHIPLjzcH5tFt50wu64yyYVcYKz/hAQTDLkRcYPgTKG9yDXQc23aUuu2EVpNn NKsqIehfFQzD1K8XwdVYiT3NXoV94kd9J+HBo4S26mT24asWWTkHpI3+B9VfEoeZuC 4tyPN9MlQMeUf3OY2AH6jwtMJH2piXMb8d4t5tGS7cvXQcXhO0AgmU8Uqk3KZ6ao5S FmOh8nSjltLKlaQ0QmeFfUl8Qs6ymwouIYwxvdOJmu7YPvqouy898PJWITqIBdLwIS vt8z2WvWBW0UA== From: Will Deacon To: Catalin Marinas , Pasha Tatashin , Andrew Morton , Uladzislau Rezki , Christoph Hellwig , David Hildenbrand , "Matthew Wilcox (Oracle)" , Mark Rutland , Anshuman Khandual , Alexandre Ghiti , Kevin Brodsky , Ryan Roberts Cc: kernel-team@android.com, Will Deacon , linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] arm64/mm: Permit lazy_mmu_mode to be nested Date: Wed, 14 May 2025 16:14:12 +0100 Message-Id: <174722572203.77262.3085803317219491344.b4-ty@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20250512150333.5589-1-ryan.roberts@arm.com> References: <20250512150333.5589-1-ryan.roberts@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit X-Stat-Signature: 9hmmjju3gib7jhfkhxg7fbqdffu37br3 X-Rspam-User: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 81C03100011 X-HE-Tag: 1747235663-17035 X-HE-Meta: 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 mvU/Qg1y rrsvW5coD8Vk13kY1AN9WenD4mFFDAYDaKm0b+lk+cwVVdN1Y77q+0AUd0MvglcssTaqqd2f8jDSo19LtRBkkApfG8XqI6s2AuoS0gpbgVMy5F+dero30QOSs5d42+2dNaXg5zEjTgm8GoBGDK7cWsSCKvuIHwQ88mrZOoEhy9WmBX97eAG2FPZVE+WfGvIIdLk07CjGuSxsZZtKTXYP1J0RuT4HV3SrQcCF/Xf+IhC2Kms292emT8LRB+7qif/sifoMwmvzwqFpu1Jzwu7PXGAbYkzghHxvITbsWtzBG+l3kXwzsExaDxjNfPirn3UmeayU6MQhBBmwm3mg2Hw8ckv6XNUJoS+v6YX+X 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 Mon, 12 May 2025 16:03:31 +0100, Ryan Roberts wrote: > lazy_mmu_mode is not supposed to permit nesting. But in practice this > does happen with CONFIG_DEBUG_PAGEALLOC, where a page allocation inside > a lazy_mmu_mode section (such as zap_pte_range()) will change > permissions on the linear map with apply_to_page_range(), which > re-enters lazy_mmu_mode (see stack trace below). > > The warning checking that nesting was not happening was previously being > triggered due to this. So let's relax by removing the warning and > tolerate nesting in the arm64 implementation. The first (inner) call to > arch_leave_lazy_mmu_mode() will flush and clear the flag such that the > remainder of the work in the outer nest behaves as if outside of lazy > mmu mode. This is safe and keeps tracking simple. > > [...] Applied to arm64 (for-next/mm), thanks! [1/1] arm64/mm: Permit lazy_mmu_mode to be nested https://git.kernel.org/arm64/c/1ef3095b1405 Cheers, -- Will https://fixes.arm64.dev https://next.arm64.dev https://will.arm64.dev