From: Peter Xu <peterx@redhat.com>
To: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>,
Baolin Wang <baolin.wang@linux.alibaba.com>,
akpm@linux-foundation.org, catalin.marinas@arm.com,
will@kernel.org, tsbogend@alpha.franken.de,
James.Bottomley@HansenPartnership.com, deller@gmx.de,
mpe@ellerman.id.au, benh@kernel.crashing.org, paulus@samba.org,
hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com,
borntraeger@linux.ibm.com, svens@linux.ibm.com,
ysato@users.sourceforge.jp, dalias@libc.org, davem@davemloft.net,
arnd@arndb.de, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-ia64@vger.kernel.org,
linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org,
linux-sh@vger.kernel.org, sparclinux@vger.kernel.org,
linux-arch@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH 3/3] mm: rmap: Fix CONT-PTE/PMD size hugetlb issue when unmapping
Date: Mon, 9 May 2022 12:41:38 -0400 [thread overview]
Message-ID: <YnlEQvipCM6hnIYT@xz-m1.local> (raw)
In-Reply-To: <927dfbf4-c899-b88a-4d58-36a637d611f9@oracle.com>
On Fri, May 06, 2022 at 12:07:13PM -0700, Mike Kravetz wrote:
> On 5/3/22 03:03, Gerald Schaefer wrote:
> > On Tue, 3 May 2022 10:19:46 +0800
> > Baolin Wang <baolin.wang@linux.alibaba.com> wrote:
> >> On 5/2/2022 10:02 PM, Gerald Schaefer wrote:
[...]
> >> Please see previous code, we'll use the original pte value to check if
> >> it is uffd-wp armed, and if need to mark it dirty though the hugetlbfs
> >> is set noop_dirty_folio().
> >>
> >> pte_install_uffd_wp_if_needed(vma, address, pvmw.pte, pteval);
> >
> > Uh, ok, that wouldn't work on s390, but we also don't have
> > CONFIG_PTE_MARKER_UFFD_WP / HAVE_ARCH_USERFAULTFD_WP set, so
> > I guess we will be fine (for now).
> >
> > Still, I find it a bit unsettling that pte_install_uffd_wp_if_needed()
> > would work on a potential hugetlb *pte, directly de-referencing it
> > instead of using huge_ptep_get().
> >
> > The !pte_none(*pte) check at the beginning would be broken in the
> > hugetlb case for s390 (not sure about other archs, but I think s390
> > might be the only exception strictly requiring huge_ptep_get()
> > for de-referencing hugetlb *pte pointers).
We could have used is_vm_hugetlb_page(vma) within the helper so as to
properly use either generic pte or hugetlb version of pte fetching. We may
want to conditionally do set_[huge_]pte_at() too at the end.
I could prepare a patch for that even if it's not really anything urgently
needed. I assume that won't need to block this patchset since we need the
pteval for pte_dirty() check anyway and uffd-wp definitely needs it too.
Thanks,
--
Peter Xu
WARNING: multiple messages have this Message-ID (diff)
From: Peter Xu <peterx@redhat.com>
To: Mike Kravetz <mike.kravetz@oracle.com>
Cc: dalias@libc.org, linux-ia64@vger.kernel.org,
linux-sh@vger.kernel.org, linux-mips@vger.kernel.org,
James.Bottomley@HansenPartnership.com, linux-mm@kvack.org,
paulus@samba.org, sparclinux@vger.kernel.org,
agordeev@linux.ibm.com, will@kernel.org,
linux-arch@vger.kernel.org, linux-s390@vger.kernel.org,
arnd@arndb.de, ysato@users.sourceforge.jp, deller@gmx.de,
catalin.marinas@arm.com,
Gerald Schaefer <gerald.schaefer@linux.ibm.com>,
borntraeger@linux.ibm.com, gor@linux.ibm.com, hca@linux.ibm.com,
Baolin Wang <baolin.wang@linux.alibaba.com>,
linux-arm-kernel@lists.infradead.org, tsbogend@alpha.franken.de,
linux-parisc@vger.kernel.org, linux-kernel@vger.kernel.org,
svens@linux.ibm.com, akpm@linux-foundation.org,
linuxppc-dev@lists.ozlabs.org, davem@davemloft.net
Subject: Re: [PATCH 3/3] mm: rmap: Fix CONT-PTE/PMD size hugetlb issue when unmapping
Date: Mon, 9 May 2022 12:41:38 -0400 [thread overview]
Message-ID: <YnlEQvipCM6hnIYT@xz-m1.local> (raw)
In-Reply-To: <927dfbf4-c899-b88a-4d58-36a637d611f9@oracle.com>
On Fri, May 06, 2022 at 12:07:13PM -0700, Mike Kravetz wrote:
> On 5/3/22 03:03, Gerald Schaefer wrote:
> > On Tue, 3 May 2022 10:19:46 +0800
> > Baolin Wang <baolin.wang@linux.alibaba.com> wrote:
> >> On 5/2/2022 10:02 PM, Gerald Schaefer wrote:
[...]
> >> Please see previous code, we'll use the original pte value to check if
> >> it is uffd-wp armed, and if need to mark it dirty though the hugetlbfs
> >> is set noop_dirty_folio().
> >>
> >> pte_install_uffd_wp_if_needed(vma, address, pvmw.pte, pteval);
> >
> > Uh, ok, that wouldn't work on s390, but we also don't have
> > CONFIG_PTE_MARKER_UFFD_WP / HAVE_ARCH_USERFAULTFD_WP set, so
> > I guess we will be fine (for now).
> >
> > Still, I find it a bit unsettling that pte_install_uffd_wp_if_needed()
> > would work on a potential hugetlb *pte, directly de-referencing it
> > instead of using huge_ptep_get().
> >
> > The !pte_none(*pte) check at the beginning would be broken in the
> > hugetlb case for s390 (not sure about other archs, but I think s390
> > might be the only exception strictly requiring huge_ptep_get()
> > for de-referencing hugetlb *pte pointers).
We could have used is_vm_hugetlb_page(vma) within the helper so as to
properly use either generic pte or hugetlb version of pte fetching. We may
want to conditionally do set_[huge_]pte_at() too at the end.
I could prepare a patch for that even if it's not really anything urgently
needed. I assume that won't need to block this patchset since we need the
pteval for pte_dirty() check anyway and uffd-wp definitely needs it too.
Thanks,
--
Peter Xu
WARNING: multiple messages have this Message-ID (diff)
From: Peter Xu <peterx@redhat.com>
To: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>,
Baolin Wang <baolin.wang@linux.alibaba.com>,
akpm@linux-foundation.org, catalin.marinas@arm.com,
will@kernel.org, tsbogend@alpha.franken.de,
James.Bottomley@HansenPartnership.com, deller@gmx.de,
mpe@ellerman.id.au, benh@kernel.crashing.org, paulus@samba.org,
hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com,
borntraeger@linux.ibm.com, svens@linux.ibm.com,
ysato@users.sourceforge.jp, dalias@libc.org, davem@davemloft.net,
arnd@arndb.de, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-ia64@vger.kernel.org,
linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org,
linux-sh@vger.kernel.org, sparclinux@vger.kernel.org,
linux-arch@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH 3/3] mm: rmap: Fix CONT-PTE/PMD size hugetlb issue when unmapping
Date: Mon, 9 May 2022 12:41:38 -0400 [thread overview]
Message-ID: <YnlEQvipCM6hnIYT@xz-m1.local> (raw)
In-Reply-To: <927dfbf4-c899-b88a-4d58-36a637d611f9@oracle.com>
On Fri, May 06, 2022 at 12:07:13PM -0700, Mike Kravetz wrote:
> On 5/3/22 03:03, Gerald Schaefer wrote:
> > On Tue, 3 May 2022 10:19:46 +0800
> > Baolin Wang <baolin.wang@linux.alibaba.com> wrote:
> >> On 5/2/2022 10:02 PM, Gerald Schaefer wrote:
[...]
> >> Please see previous code, we'll use the original pte value to check if
> >> it is uffd-wp armed, and if need to mark it dirty though the hugetlbfs
> >> is set noop_dirty_folio().
> >>
> >> pte_install_uffd_wp_if_needed(vma, address, pvmw.pte, pteval);
> >
> > Uh, ok, that wouldn't work on s390, but we also don't have
> > CONFIG_PTE_MARKER_UFFD_WP / HAVE_ARCH_USERFAULTFD_WP set, so
> > I guess we will be fine (for now).
> >
> > Still, I find it a bit unsettling that pte_install_uffd_wp_if_needed()
> > would work on a potential hugetlb *pte, directly de-referencing it
> > instead of using huge_ptep_get().
> >
> > The !pte_none(*pte) check at the beginning would be broken in the
> > hugetlb case for s390 (not sure about other archs, but I think s390
> > might be the only exception strictly requiring huge_ptep_get()
> > for de-referencing hugetlb *pte pointers).
We could have used is_vm_hugetlb_page(vma) within the helper so as to
properly use either generic pte or hugetlb version of pte fetching. We may
want to conditionally do set_[huge_]pte_at() too at the end.
I could prepare a patch for that even if it's not really anything urgently
needed. I assume that won't need to block this patchset since we need the
pteval for pte_dirty() check anyway and uffd-wp definitely needs it too.
Thanks,
--
Peter Xu
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
WARNING: multiple messages have this Message-ID (diff)
From: Peter Xu <peterx@redhat.com>
To: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>,
Baolin Wang <baolin.wang@linux.alibaba.com>,
akpm@linux-foundation.org, catalin.marinas@arm.com,
will@kernel.org, tsbogend@alpha.franken.de,
James.Bottomley@HansenPartnership.com, deller@gmx.de,
mpe@ellerman.id.au, benh@kernel.crashing.org, paulus@samba.org,
hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com,
borntraeger@linux.ibm.com, svens@linux.ibm.com,
ysato@users.sourceforge.jp, dalias@libc.org, davem@davemloft.net,
arnd@arndb.de, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-ia64@vger.kernel.org,
linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org,
linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org,
linux-sh@vger.kernel.org, sparclinux@vger.kernel.org,
linux-arch@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH 3/3] mm: rmap: Fix CONT-PTE/PMD size hugetlb issue when unmapping
Date: Mon, 09 May 2022 16:41:38 +0000 [thread overview]
Message-ID: <YnlEQvipCM6hnIYT@xz-m1.local> (raw)
In-Reply-To: <927dfbf4-c899-b88a-4d58-36a637d611f9@oracle.com>
On Fri, May 06, 2022 at 12:07:13PM -0700, Mike Kravetz wrote:
> On 5/3/22 03:03, Gerald Schaefer wrote:
> > On Tue, 3 May 2022 10:19:46 +0800
> > Baolin Wang <baolin.wang@linux.alibaba.com> wrote:
> >> On 5/2/2022 10:02 PM, Gerald Schaefer wrote:
[...]
> >> Please see previous code, we'll use the original pte value to check if
> >> it is uffd-wp armed, and if need to mark it dirty though the hugetlbfs
> >> is set noop_dirty_folio().
> >>
> >> pte_install_uffd_wp_if_needed(vma, address, pvmw.pte, pteval);
> >
> > Uh, ok, that wouldn't work on s390, but we also don't have
> > CONFIG_PTE_MARKER_UFFD_WP / HAVE_ARCH_USERFAULTFD_WP set, so
> > I guess we will be fine (for now).
> >
> > Still, I find it a bit unsettling that pte_install_uffd_wp_if_needed()
> > would work on a potential hugetlb *pte, directly de-referencing it
> > instead of using huge_ptep_get().
> >
> > The !pte_none(*pte) check at the beginning would be broken in the
> > hugetlb case for s390 (not sure about other archs, but I think s390
> > might be the only exception strictly requiring huge_ptep_get()
> > for de-referencing hugetlb *pte pointers).
We could have used is_vm_hugetlb_page(vma) within the helper so as to
properly use either generic pte or hugetlb version of pte fetching. We may
want to conditionally do set_[huge_]pte_at() too at the end.
I could prepare a patch for that even if it's not really anything urgently
needed. I assume that won't need to block this patchset since we need the
pteval for pte_dirty() check anyway and uffd-wp definitely needs it too.
Thanks,
--
Peter Xu
next prev parent reply other threads:[~2022-05-09 16:41 UTC|newest]
Thread overview: 88+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-29 8:14 [PATCH 0/3] Fix CONT-PTE/PMD size hugetlb issue when unmapping or migrating Baolin Wang
2022-04-29 8:14 ` Baolin Wang
2022-04-29 8:14 ` Baolin Wang
2022-04-29 8:14 ` Baolin Wang
2022-04-29 8:14 ` [PATCH 1/3] mm: change huge_ptep_clear_flush() to return the original pte Baolin Wang
2022-04-29 8:14 ` Baolin Wang
2022-04-29 8:14 ` Baolin Wang
2022-04-29 8:14 ` Baolin Wang
2022-05-05 23:15 ` Mike Kravetz
2022-05-05 23:15 ` Mike Kravetz
2022-05-05 23:15 ` Mike Kravetz
2022-05-05 23:15 ` Mike Kravetz
2022-05-06 3:02 ` Baolin Wang
2022-05-06 3:02 ` Baolin Wang
2022-05-06 3:02 ` Baolin Wang
2022-05-06 3:02 ` Baolin Wang
2022-04-29 8:14 ` [PATCH 2/3] mm: rmap: Fix CONT-PTE/PMD size hugetlb issue when migration Baolin Wang
2022-04-29 8:14 ` Baolin Wang
2022-04-29 8:14 ` Baolin Wang
2022-04-29 8:14 ` Baolin Wang
2022-05-05 23:53 ` Mike Kravetz
2022-05-05 23:53 ` Mike Kravetz
2022-05-05 23:53 ` Mike Kravetz
2022-05-05 23:53 ` Mike Kravetz
2022-05-06 3:39 ` Baolin Wang
2022-05-06 3:39 ` Baolin Wang
2022-05-06 3:39 ` Baolin Wang
2022-05-06 3:39 ` Baolin Wang
2022-05-06 17:56 ` Mike Kravetz
2022-05-06 17:56 ` Mike Kravetz
2022-05-06 17:56 ` Mike Kravetz
2022-05-06 17:56 ` Mike Kravetz
2022-05-07 2:33 ` Baolin Wang
2022-05-07 2:33 ` Baolin Wang
2022-05-07 2:33 ` Baolin Wang
2022-05-07 2:33 ` Baolin Wang
2022-05-08 9:19 ` Baolin Wang
2022-05-08 9:19 ` Baolin Wang
2022-05-08 9:19 ` Baolin Wang
2022-05-08 9:19 ` Baolin Wang
2022-04-29 8:14 ` [PATCH 3/3] mm: rmap: Fix CONT-PTE/PMD size hugetlb issue when unmapping Baolin Wang
2022-04-29 8:14 ` Baolin Wang
2022-04-29 8:14 ` Baolin Wang
2022-04-29 8:14 ` Baolin Wang
2022-04-29 20:02 ` Gerald Schaefer
2022-04-29 20:02 ` Gerald Schaefer
2022-04-29 20:02 ` Gerald Schaefer
2022-04-29 20:02 ` Gerald Schaefer
2022-04-30 3:22 ` Baolin Wang
2022-04-30 3:22 ` Baolin Wang
2022-04-30 3:22 ` Baolin Wang
2022-04-30 3:22 ` Baolin Wang
2022-05-02 14:02 ` Gerald Schaefer
2022-05-02 14:02 ` Gerald Schaefer
2022-05-02 14:02 ` Gerald Schaefer
2022-05-02 14:02 ` Gerald Schaefer
2022-05-03 2:19 ` Baolin Wang
2022-05-03 2:19 ` Baolin Wang
2022-05-03 2:19 ` Baolin Wang
2022-05-03 2:19 ` Baolin Wang
2022-05-03 10:03 ` Gerald Schaefer
2022-05-03 10:03 ` Gerald Schaefer
2022-05-03 10:03 ` Gerald Schaefer
2022-05-03 10:03 ` Gerald Schaefer
2022-05-03 13:33 ` Baolin Wang
2022-05-03 13:33 ` Baolin Wang
2022-05-03 13:33 ` Baolin Wang
2022-05-03 13:33 ` Baolin Wang
2022-05-06 19:07 ` Mike Kravetz
2022-05-06 19:07 ` Mike Kravetz
2022-05-06 19:07 ` Mike Kravetz
2022-05-06 19:07 ` Mike Kravetz
2022-05-09 16:41 ` Peter Xu [this message]
2022-05-09 16:41 ` Peter Xu
2022-05-09 16:41 ` Peter Xu
2022-05-09 16:41 ` Peter Xu
2022-05-10 1:28 ` Baolin Wang
2022-05-10 1:28 ` Baolin Wang
2022-05-10 1:28 ` Baolin Wang
2022-05-10 1:28 ` Baolin Wang
2022-05-06 18:55 ` Mike Kravetz
2022-05-06 18:55 ` Mike Kravetz
2022-05-06 18:55 ` Mike Kravetz
2022-05-06 18:55 ` Mike Kravetz
2022-05-07 1:32 ` Baolin Wang
2022-05-07 1:32 ` Baolin Wang
2022-05-07 1:32 ` Baolin Wang
2022-05-07 1:32 ` Baolin Wang
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