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[79.139.233.37]) by smtp.googlemail.com with ESMTPSA id v8sm198edw.21.2020.01.28.15.35.26 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 28 Jan 2020 15:35:27 -0800 (PST) Subject: Re: [PATCH 3/5] mm/mremap: use pmd_addr_end to calculate next in move_page_tables() To: Wei Yang Cc: Russell King - ARM Linux , akpm@linux-foundation.org, dan.j.williams@intel.com, aneesh.kumar@linux.ibm.com, kirill@shutemov.name, yang.shi@linux.alibaba.com, thellstrom@vmware.com, Thierry Reding , Jon Hunter , linux-kernel@vger.kernel.org, linux-mm@kvack.org, "linux-tegra@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" References: <20200117232254.2792-1-richardw.yang@linux.intel.com> <20200117232254.2792-4-richardw.yang@linux.intel.com> <7147774a-14e9-4ff3-1548-4565f0d214d5@gmail.com> <20200128004301.GD20624@richard> <20200128232907.GA11467@richard> From: Dmitry Osipenko Message-ID: <27b70b0c-7945-cc85-8321-d9e4b6f17865@gmail.com> Date: Wed, 29 Jan 2020 02:35:25 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.3.0 MIME-Version: 1.0 In-Reply-To: <20200128232907.GA11467@richard> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 29.01.2020 02:29, Wei Yang пишет: > On Tue, Jan 28, 2020 at 06:59:48PM +0300, Dmitry Osipenko wrote: >> 28.01.2020 03:43, Wei Yang пишет: >>> On Sun, Jan 26, 2020 at 05:47:57PM +0300, Dmitry Osipenko wrote: >>>> 18.01.2020 02:22, Wei Yang пишет: >>>>> Use the general helper instead of do it by hand. >>>>> >>>>> Signed-off-by: Wei Yang >>>>> --- >>>>> mm/mremap.c | 7 ++----- >>>>> 1 file changed, 2 insertions(+), 5 deletions(-) >>>>> >>>>> diff --git a/mm/mremap.c b/mm/mremap.c >>>>> index c2af8ba4ba43..a258914f3ee1 100644 >>>>> --- a/mm/mremap.c >>>>> +++ b/mm/mremap.c >>>>> @@ -253,11 +253,8 @@ unsigned long move_page_tables(struct vm_area_struct *vma, >>>>> >>>>> for (; old_addr < old_end; old_addr += extent, new_addr += extent) { >>>>> cond_resched(); >>>>> - next = (old_addr + PMD_SIZE) & PMD_MASK; >>>>> - /* even if next overflowed, extent below will be ok */ >>>>> + next = pmd_addr_end(old_addr, old_end); >>>>> extent = next - old_addr; >>>>> - if (extent > old_end - old_addr) >>>>> - extent = old_end - old_addr; >>>>> old_pmd = get_old_pmd(vma->vm_mm, old_addr); >>>>> if (!old_pmd) >>>>> continue; >>>>> @@ -301,7 +298,7 @@ unsigned long move_page_tables(struct vm_area_struct *vma, >>>>> >>>>> if (pte_alloc(new_vma->vm_mm, new_pmd)) >>>>> break; >>>>> - next = (new_addr + PMD_SIZE) & PMD_MASK; >>>>> + next = pmd_addr_end(new_addr, new_addr + len); >>>>> if (extent > next - new_addr) >>>>> extent = next - new_addr; >>>>> move_ptes(vma, old_pmd, old_addr, old_addr + extent, new_vma, >>>>> >>>> >>>> Hello Wei, >>>> >>>> Starting with next-20200122, I'm seeing the following in KMSG on NVIDIA >>>> Tegra (ARM32): >>>> >>>> BUG: Bad rss-counter state mm:(ptrval) type:MM_ANONPAGES val:190 >>>> >>> >>> Thanks. >>> >>> Would you mind letting me know which case you are testing? >> >> Nothing special, systemd starts to fall apart during boot. >> >>> Or the special thing is 32-bit platform? >> I have a limited knowledge about mm/, so can't provide detailed explanation. >> >> Please take a look at this: >> >> [1] >> https://elixir.bootlin.com/linux/v5.5/source/arch/arm/include/asm/pgtable-2level.h#L210 >> >> [2] >> https://elixir.bootlin.com/linux/v5.5/source/include/asm-generic/pgtable.h#L549 >> >> [3] >> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c0ba10b512eb2e2a3888b6e6cc0e089f5e7a191b > > Thanks, I see the difference here. > > If this is the case, we can't use pmd_addr_end() to simplify the calculation. > This changes the behavior. > > I would prepare another patch set to fix this. Would you mind helping me > verify on your platform? Sure, please feel free to CC me on that patch.