mmu notifier calls in apply_to_page_range()
in [Kernel]
|
Prev: BUG: unable to handle kernel paging request at 40000000 __alloc_memory_core_early+0x147/0x1d6
Next: Yet another 2.6.35 regression (AGP)?
From: Jeremy Fitzhardinge on 9 Jul 2010 13:40 On 07/09/2010 09:22 AM, Andrea Arcangeli wrote: > mmu notifier only relevant for userland mappings, not kernel > mappings. I don't know about the xen use, but for vmalloc certainly it > can't be a problem to remove those two mmu notifier invalidates. > > Only bit that is worrysome is the mm == &init_mm > pte_alloc_kernel|pte_alloc_map_lock. That seems to imply it may also > be used to mangle over userland. But apparently all users are passing > &init_mm as expected. I guess if you remove the mm parameter and you > default to &init_mm definitely there will be no risk in removing the > mmu notifier range_start/end invalidates. > No, we do have some users which use it on user memory. But those users are using it as part of their own mmu notifier backend, so the recursive calls are causing a problem. My point is that anyone using apply_to_page_range should be making their own calls to mmu notifiers as appropriate to whatever they're doing. J -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Jeremy Fitzhardinge on 9 Jul 2010 13:50 On 07/09/2010 10:36 AM, Andrea Arcangeli wrote: > I'm not opposed to removing it, I've been wondering if it made any > sense in the first place but then there was no point not to add > it. Just calling apply_to_page_range in non blocking context doesn't > look so good. > That's a good point. It should be safe if the pagetable is already fully populated; I should double-check that's true in our case. J -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Andrea Arcangeli on 9 Jul 2010 14:40
On Fri, Jul 09, 2010 at 10:41:51AM -0700, Jeremy Fitzhardinge wrote: > On 07/09/2010 10:36 AM, Andrea Arcangeli wrote: > > I'm not opposed to removing it, I've been wondering if it made any > > sense in the first place but then there was no point not to add > > it. Just calling apply_to_page_range in non blocking context doesn't > > look so good. > > > > That's a good point. It should be safe if the pagetable is already > fully populated; I should double-check that's true in our case. Yes in that case is safe, but it'd be more strict to use pmd/*_offset then. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |