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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
Download Patch File Download Diff File Expand all files Collapse all files

18
arch/x86/mm/pageattr.c
View File

@@ -57,12 +57,10 @@ static unsigned long direct_pages_count[PG_LEVEL_NUM];
void update_page_count(int level, unsigned long pages)
{
unsigned long flags;
/* Protect against CPA */
spin_lock_irqsave(&pgd_lock, flags);
spin_lock(&pgd_lock);
direct_pages_count[level] += pages;
spin_unlock_irqrestore(&pgd_lock, flags);
spin_unlock(&pgd_lock);
}
static void split_page_count(int level)
@@ -394,7 +392,7 @@ static int
try_preserve_large_page(pte_t *kpte, unsigned long address,
struct cpa_data *cpa)
{
unsigned long nextpage_addr, numpages, pmask, psize, flags, addr, pfn;
unsigned long nextpage_addr, numpages, pmask, psize, addr, pfn;
pte_t new_pte, old_pte, *tmp;
pgprot_t old_prot, new_prot, req_prot;
int i, do_split = 1;
@@ -403,7 +401,7 @@ try_preserve_large_page(pte_t *kpte, unsigned long address,
if (cpa->force_split)
return 1;
spin_lock_irqsave(&pgd_lock, flags);
spin_lock(&pgd_lock);
/*
* Check for races, another CPU might have split this page
* up already:
@@ -498,14 +496,14 @@ try_preserve_large_page(pte_t *kpte, unsigned long address,
}
out_unlock:
spin_unlock_irqrestore(&pgd_lock, flags);
spin_unlock(&pgd_lock);
return do_split;
}
static int split_large_page(pte_t *kpte, unsigned long address)
{
unsigned long flags, pfn, pfninc = 1;
unsigned long pfn, pfninc = 1;
unsigned int i, level;
pte_t *pbase, *tmp;
pgprot_t ref_prot;
@@ -519,7 +517,7 @@ static int split_large_page(pte_t *kpte, unsigned long address)
if (!base)
return -ENOMEM;
spin_lock_irqsave(&pgd_lock, flags);
spin_lock(&pgd_lock);
/*
* Check for races, another CPU might have split this page
* up for us already:
@@ -591,7 +589,7 @@ out_unlock:
*/
if (base)
__free_page(base);
spin_unlock_irqrestore(&pgd_lock, flags);
spin_unlock(&pgd_lock);
return 0;
}