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x86/mm: Fix pgd_lock deadlock

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It's forbidden to take the page_table_lock with the irq disabled
or if there's contention the IPIs (for tlb flushes) sent with
the page_table_lock held will never run leading to a deadlock.

Nobody takes the pgd_lock from irq context so the _irqsave can be
removed.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
Tested-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: <stable@kernel.org>
LKML-Reference: <201102162345.p1GNjMjm021738@imap1.linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Andrea Arcangeli
2011-02-16 15:45:22 -08:00
committed by Ingo Molnar
parent f86268549f
commit a79e53d856
5 changed files with 22 additions and 30 deletions
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11
arch/x86/mm/pgtable.c
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@@ -121,14 +121,12 @@ static void pgd_ctor(struct mm_struct *mm, pgd_t *pgd)
static void pgd_dtor(pgd_t *pgd)
{
unsigned long flags; /* can be called from interrupt context */
if (SHARED_KERNEL_PMD)
return;
spin_lock_irqsave(&pgd_lock, flags);
spin_lock(&pgd_lock);
pgd_list_del(pgd);
spin_unlock_irqrestore(&pgd_lock, flags);
spin_unlock(&pgd_lock);
}
/*
@@ -260,7 +258,6 @@ pgd_t *pgd_alloc(struct mm_struct *mm)
{
pgd_t *pgd;
pmd_t *pmds[PREALLOCATED_PMDS];
unsigned long flags;
pgd = (pgd_t *)__get_free_page(PGALLOC_GFP);
@@ -280,12 +277,12 @@ pgd_t *pgd_alloc(struct mm_struct *mm)
* respect to anything walking the pgd_list, so that they
* never see a partially populated pgd.
*/
spin_lock_irqsave(&pgd_lock, flags);
spin_lock(&pgd_lock);
pgd_ctor(mm, pgd);
pgd_prepopulate_pmd(mm, pgd, pmds);
spin_unlock_irqrestore(&pgd_lock, flags);
spin_unlock(&pgd_lock);
return pgd;