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| author | Chris Metcalf <cmetcalf@tilera.com> | 2012-03-29 15:34:52 -0400 |
|---|---|---|
| committer | Chris Metcalf <cmetcalf@tilera.com> | 2012-04-02 12:13:02 -0400 |
| commit | 48292738d06d7b46d861652ef59bd03be931c2c9 (patch) | |
| tree | b296408a3c451199cb76372e218c3c3c572d3759 /arch/tile/mm | |
| parent | 6731aa9eae3e94b094a44d2aea02387a39202fbc (diff) | |
| download | op-kernel-dev-48292738d06d7b46d861652ef59bd03be931c2c9.zip op-kernel-dev-48292738d06d7b46d861652ef59bd03be931c2c9.tar.gz | |
arch/tile: don't wait for migrating PTEs in an NMI handler
Doing so raises the possibility of self-deadlock if we are waiting
for a backtrace for an oprofile or perf interrupt while we are
in the middle of migrating our own stack page.
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
Diffstat (limited to 'arch/tile/mm')
| -rw-r--r-- | arch/tile/mm/fault.c | 13 |
1 files changed, 10 insertions, 3 deletions
diff --git a/arch/tile/mm/fault.c b/arch/tile/mm/fault.c index cac17c4..a1da473 100644 --- a/arch/tile/mm/fault.c +++ b/arch/tile/mm/fault.c @@ -203,9 +203,14 @@ static pgd_t *get_current_pgd(void) * interrupt or a critical region, and must do as little as possible. * Similarly, we can't use atomic ops here, since we may be handling a * fault caused by an atomic op access. + * + * If we find a migrating PTE while we're in an NMI context, and we're + * at a PC that has a registered exception handler, we don't wait, + * since this thread may (e.g.) have been interrupted while migrating + * its own stack, which would then cause us to self-deadlock. */ static int handle_migrating_pte(pgd_t *pgd, int fault_num, - unsigned long address, + unsigned long address, unsigned long pc, int is_kernel_mode, int write) { pud_t *pud; @@ -227,6 +232,8 @@ static int handle_migrating_pte(pgd_t *pgd, int fault_num, pte_offset_kernel(pmd, address); pteval = *pte; if (pte_migrating(pteval)) { + if (in_nmi() && search_exception_tables(pc)) + return 0; wait_for_migration(pte); return 1; } @@ -300,7 +307,7 @@ static int handle_page_fault(struct pt_regs *regs, * rather than trying to patch up the existing PTE. */ pgd = get_current_pgd(); - if (handle_migrating_pte(pgd, fault_num, address, + if (handle_migrating_pte(pgd, fault_num, address, regs->pc, is_kernel_mode, write)) return 1; @@ -665,7 +672,7 @@ struct intvec_state do_page_fault_ics(struct pt_regs *regs, int fault_num, */ if (fault_num == INT_DTLB_ACCESS) write = 1; - if (handle_migrating_pte(pgd, fault_num, address, 1, write)) + if (handle_migrating_pte(pgd, fault_num, address, pc, 1, write)) return state; /* Return zero so that we continue on with normal fault handling. */ |
