[next-20150119]regression (mm)?
Kirill A. Shutemov
kirill at shutemov.name
Mon Jan 26 04:00:43 PST 2015
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>
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
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