[next-20150119]regression (mm)?
Tyler Baker
tyler.baker at linaro.org
Mon Jan 26 14:38:26 PST 2015
On 26 January 2015 at 04:00, Kirill A. Shutemov <kirill at shutemov.name> wrote:
> On Fri, Jan 23, 2015 at 10:37:46PM -0600, Nishanth Menon wrote:
>> On 03:13-20150124, Kirill A. Shutemov wrote:
>> > > >> On 09:39-20150123, Tyler Baker wrote:
>> [...]
>> > > >> > I just reviewed the boot logs for next-20150123 and there still seems
>> > > >> > to be a related issue. I've been boot testing
>> > > >> > multi_v7_defconfig+CONFIG_ARM_LPAE=y kernel configurations which still
>> > > >> > seem broken.
>> [...]
>> > Okay, proof of concept patch is below. It's going to break every other
>> > architecture with FIRST_USER_ADDRESS != 0, but I think it's cleaner way to
>> > go.
>>
>> Testing on my end:
>>
>> just ran through this set (+ logs similar to Tyler's from my side):
>>
>> next-20150123 (multi_v7_defconfig == !LPAE)
>> 1: BeagleBoard-X15(am57xx-evm): BOOT: PASS: http://paste.ubuntu.org.cn/2219449
>> 2: dra72x-evm: BOOT: PASS: http://paste.ubuntu.org.cn/2219450
>> 3: dra7xx-evm: BOOT: PASS: http://paste.ubuntu.org.cn/2219451
>> 4: omap5-evm: BOOT: PASS: http://paste.ubuntu.org.cn/2219452
>> TOTAL = 4 boards, Booted Boards = 4, No Boot boards = 0
>>
>> next-20150123-LPAE-Logging enabled[1] (multi_v7_defconfig +LPAE)
>> 1: BeagleBoard-X15(am57xx-evm): BOOT: FAIL: http://paste.ubuntu.org.cn/2220938
>> 2: dra72x-evm: BOOT: FAIL: http://paste.ubuntu.org.cn/2220943
>> 3: dra7xx-evm: BOOT: FAIL: http://paste.ubuntu.org.cn/2220947
>> 4: omap5-evm: BOOT: FAIL: http://paste.ubuntu.org.cn/2220955
>> TOTAL = 4 boards, Booted Boards = 0, No Boot boards = 4
>>
>> next-20150123-LPAE-new-patch [2] (multi_v7_defconfig + LPAE)
>> 1: BeagleBoard-X15(am57xx-evm): BOOT: PASS: http://paste.ubuntu.org.cn/2221047
>> 2: dra72x-evm: BOOT: PASS: http://paste.ubuntu.org.cn/2221065
>> 3: dra7xx-evm: BOOT: PASS: http://paste.ubuntu.org.cn/2221069
>> 4: omap5-evm: BOOT: PASS: http://paste.ubuntu.org.cn/2221070
>> TOTAL = 4 boards, Booted Boards = 4, No Boot boards = 0
>>
>> next-20150123-new-patch[2] (multi_v7_defconfig == !LPAE)
>> 1: am335x-evm: BOOT: PASS: http://paste.ubuntu.org.cn/2221277
>> 2: am335x-sk: BOOT: PASS: http://paste.ubuntu.org.cn/2221278
>> 3: am437x-sk: BOOT: FAIL: http://paste.ubuntu.org.cn/2221279 (unrelated)
>> 4: am43xx-epos: BOOT: PASS: http://paste.ubuntu.org.cn/2221280
>> 5: am43xx-gpevm: BOOT: PASS: http://paste.ubuntu.org.cn/2221281
>> 6: BeagleBoard-X15(am57xx-evm): BOOT: PASS: http://paste.ubuntu.org.cn/2221282
>> 7: BeagleBoard-XM: BOOT: FAIL: http://paste.ubuntu.org.cn/2221283 (unrelated)
>> 8: beagleboard-vanilla: BOOT: PASS: http://paste.ubuntu.org.cn/2221284
>> 9: beaglebone-black: BOOT: PASS: http://paste.ubuntu.org.cn/2221285
>> 10: beaglebone: BOOT: FAIL: http://paste.ubuntu.org.cn/2221286 (unrelated)
>> 11: dra72x-evm: BOOT: PASS: http://paste.ubuntu.org.cn/2221287
>> 12: dra7xx-evm: BOOT: PASS: http://paste.ubuntu.org.cn/2221288
>> 13: omap5-evm: BOOT: PASS: http://paste.ubuntu.org.cn/2221289
>> 14: pandaboard-es: BOOT: PASS: http://paste.ubuntu.org.cn/2221290
>> 15: pandaboard-vanilla: BOOT: PASS: http://paste.ubuntu.org.cn/2221291
>> 16: sdp4430: BOOT: PASS: http://paste.ubuntu.org.cn/2221292
>> TOTAL = 16 boards, Booted Boards = 13, No Boot boards = 3
>>
>> next-20150123-new-patch[2] (omap2plus_defconfig)
>> 1: am335x-evm: BOOT: PASS: http://paste.ubuntu.org.cn/2221653
>> 2: am335x-sk: BOOT: PASS: http://paste.ubuntu.org.cn/2221654
>> 3: am437x-sk: BOOT: PASS: http://paste.ubuntu.org.cn/2221656
>> 4: am43xx-epos: BOOT: PASS: http://paste.ubuntu.org.cn/2221659
>> 5: am43xx-gpevm: BOOT: PASS: http://paste.ubuntu.org.cn/2221660
>> 6: BeagleBoard-X15(am57xx-evm): BOOT: PASS: http://paste.ubuntu.org.cn/2221661
>> 7: BeagleBoard-XM: BOOT: PASS: http://paste.ubuntu.org.cn/2221670
>> 8: beagleboard-vanilla: BOOT: PASS: http://paste.ubuntu.org.cn/2221676
>> 9: beaglebone-black: BOOT: PASS: http://paste.ubuntu.org.cn/2221683
>> 10: beaglebone: BOOT: PASS: http://paste.ubuntu.org.cn/2221690
>> 11: dra72x-evm: BOOT: PASS: http://paste.ubuntu.org.cn/2221692
>> 12: dra7xx-evm: BOOT: PASS: http://paste.ubuntu.org.cn/2221695
>> 13: omap5-evm: BOOT: PASS: http://paste.ubuntu.org.cn/2221700
>> 14: pandaboard-es: BOOT: PASS: http://paste.ubuntu.org.cn/2221704
>> 15: pandaboard-vanilla: BOOT: PASS: http://paste.ubuntu.org.cn/2221707
>> 16: sdp4430: BOOT: PASS: http://paste.ubuntu.org.cn/2221713
>> TOTAL = 16 boards, Booted Boards = 16, No Boot boards = 0
>
> Okay thanks. Here's proper patch.
>
> From 8f9845ab8d972164b700ff3e3ce53484cceb942b Mon Sep 17 00:00:00 2001
> From: "Kirill A. Shutemov" <kirill.shutemov at linux.intel.com>
> Date: Mon, 26 Jan 2015 12:07:54 +0200
> Subject: [PATCH 1/2] mm: fix false-positive warning on exit due mm_nr_pmds(mm)
>
> The problem is that we check nr_ptes/nr_pmds in exit_mmap() which happens
> *before* pgd_free(). And if an arch does pte/pmd allocation in pgd_alloc()
> and frees them in pgd_free() we see offset in counters by the time of the
> checks.
>
> We tried to workaround this by offsetting expected counter value
> according to FIRST_USER_ADDRESS for both nr_pte and nr_pmd in
> exit_mmap(). But it doesn't work in some cases:
>
> 1. ARM with LPAE enabled also has non-zero USER_PGTABLES_CEILING, but
> upper addresses occupied with huge pmd entries, so the trick with
> offsetting expected counter value will get really ugly: we will have
> to apply it nr_pmds, but not nr_ptes.
>
> 2. Metag has non-zero FIRST_USER_ADDRESS, but doesn't do allocation
> pte/pmd page tables allocation in pgd_alloc(), just setup a pgd entry
> which is allocated at boot and shared accross all processes.
>
> The proposal is to move the check to check_mm() which happens *after*
> pgd_free() and do proper accounting during pgd_alloc() and pgd_free()
> which would bring counters to zero if nothing leaked.
>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov at linux.intel.com>
I've tested this patch on top of linux-next [1] on a various array of
arm, arm64 and x86 hardware. I can confirm the issue with
CONFIG_ARM_LPAE=y has been resolved with no additional regressions
detected. The results can be found here [2].
Feel free to add:
Tested-by: Tyler Baker <tyler.baker at linaro.org>
> Reported-by: Tyler Baker <tyler.baker at linaro.org>
> Tested-by: Nishanth Menon <nm at ti.com>
> Cc: Russell King <linux at arm.linux.org.uk>
> Cc: James Hogan <james.hogan at imgtec.com>
> Cc: Guan Xuetao <gxt at mprc.pku.edu.cn>
> ---
> arch/arm/mm/pgd.c | 4 ++++
> arch/unicore32/mm/pgd.c | 3 +++
> kernel/fork.c | 8 ++++++++
> mm/mmap.c | 5 -----
> 4 files changed, 15 insertions(+), 5 deletions(-)
>
> diff --git a/arch/arm/mm/pgd.c b/arch/arm/mm/pgd.c
> index 249379535be2..a3681f11dd9f 100644
> --- a/arch/arm/mm/pgd.c
> +++ b/arch/arm/mm/pgd.c
> @@ -97,6 +97,7 @@ pgd_t *pgd_alloc(struct mm_struct *mm)
>
> no_pte:
> pmd_free(mm, new_pmd);
> + mm_dec_nr_pmds(mm);
> no_pmd:
> pud_free(mm, new_pud);
> no_pud:
> @@ -130,9 +131,11 @@ void pgd_free(struct mm_struct *mm, pgd_t *pgd_base)
> pte = pmd_pgtable(*pmd);
> pmd_clear(pmd);
> pte_free(mm, pte);
> + atomic_long_dec(&mm->nr_ptes);
> no_pmd:
> pud_clear(pud);
> pmd_free(mm, pmd);
> + mm_dec_nr_pmds(mm);
> no_pud:
> pgd_clear(pgd);
> pud_free(mm, pud);
> @@ -152,6 +155,7 @@ no_pgd:
> pmd = pmd_offset(pud, 0);
> pud_clear(pud);
> pmd_free(mm, pmd);
> + mm_dec_nr_pmds(mm);
> pgd_clear(pgd);
> pud_free(mm, pud);
> }
> diff --git a/arch/unicore32/mm/pgd.c b/arch/unicore32/mm/pgd.c
> index 08b8d4295e70..1bc00d0305d4 100644
> --- a/arch/unicore32/mm/pgd.c
> +++ b/arch/unicore32/mm/pgd.c
> @@ -69,6 +69,7 @@ pgd_t *get_pgd_slow(struct mm_struct *mm)
>
> no_pte:
> pmd_free(mm, new_pmd);
> + mm_dec_nr_pmds(mm);
> no_pmd:
> free_pages((unsigned long)new_pgd, 0);
> no_pgd:
> @@ -96,7 +97,9 @@ void free_pgd_slow(struct mm_struct *mm, pgd_t *pgd)
> pte = pmd_pgtable(*pmd);
> pmd_clear(pmd);
> pte_free(mm, pte);
> + atomic_long_dec(&mm->nr_ptes);
> pmd_free(mm, pmd);
> + mm_dec_nr_pmds(mm)
> free:
> free_pages((unsigned long) pgd, 0);
> }
> diff --git a/kernel/fork.c b/kernel/fork.c
> index c99098c52641..76d6f292274c 100644
> --- a/kernel/fork.c
> +++ b/kernel/fork.c
> @@ -606,6 +606,14 @@ static void check_mm(struct mm_struct *mm)
> printk(KERN_ALERT "BUG: Bad rss-counter state "
> "mm:%p idx:%d val:%ld\n", mm, i, x);
> }
> +
> + if (atomic_long_read(&mm->nr_ptes))
> + pr_alert("BUG: non-zero nr_ptes on freeing mm: %ld",
> + atomic_long_read(&mm->nr_ptes));
> + if (mm_nr_pmds(mm))
> + pr_alert("BUG: non-zero nr_pmds on freeing mm: %ld",
> + mm_nr_pmds(mm));
> +
> #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
> VM_BUG_ON_MM(mm->pmd_huge_pte, mm);
> #endif
> diff --git a/mm/mmap.c b/mm/mmap.c
> index 6a7d36d133fb..c5f44682c0d1 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -2851,11 +2851,6 @@ void exit_mmap(struct mm_struct *mm)
> vma = remove_vma(vma);
> }
> vm_unacct_memory(nr_accounted);
> -
> - WARN_ON(atomic_long_read(&mm->nr_ptes) >
> - round_up(FIRST_USER_ADDRESS, PMD_SIZE) >> PMD_SHIFT);
> - WARN_ON(mm_nr_pmds(mm) >
> - round_up(FIRST_USER_ADDRESS, PUD_SIZE) >> PUD_SHIFT);
> }
>
> /* Insert vm structure into process list sorted by address
> --
> Kirill A. Shutemov
[1] https://git.linaro.org/people/tyler.baker/linux-next.git/shortlog/refs/heads/next-testing
[2] http://kernelci.org/boot/all/job/tbaker/kernel/v3.19-rc5-5174-g384ba8a33c70/
Thanks,
Tyler
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