From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wei Yang Subject: Re: [PATCH 3/5] mm/mremap: use pmd_addr_end to calculate next in move_page_tables() Date: Wed, 29 Jan 2020 07:29:07 +0800 Message-ID: <20200128232907.GA11467@richard> 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> Reply-To: Wei Yang Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Dmitry Osipenko Cc: Wei Yang , Russell King - ARM Linux , akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, dan.j.williams-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org, aneesh.kumar-tEXmvtCZX7AybS5Ee8rs3A@public.gmane.org, kirill-oKw7cIdHH8eLwutG50LtGA@public.gmane.org, yang.shi-KPsoFbNs7GizrGE5bRqYAgC/G2K4zDHf@public.gmane.org, thellstrom-pghWNbHTmq7QT0dZR+AlfA@public.gmane.org, Thierry Reding , Jon Hunter , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, "linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" List-Id: linux-tegra@vger.kernel.org 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? -- Wei Yang Help you, Help me