On Fri 21-03-14 14:17:32, John Stultz wrote: > Users of volatile ranges will need to know if memory was discarded. > This patch adds the purged state tracking required to inform userland > when it marks memory as non-volatile that some memory in that range > was purged and needs to be regenerated. > > This simplified implementation which uses some of the logic from > Minchan's earlier efforts, so credit to Minchan for his work. > > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > Cc: Android Kernel Team <kernel-team@xxxxxxxxxxx> > Cc: Johannes Weiner <hannes@xxxxxxxxxxx> > Cc: Robert Love <rlove@xxxxxxxxxx> > Cc: Mel Gorman <mel@xxxxxxxxx> > Cc: Hugh Dickins <hughd@xxxxxxxxxx> > Cc: Dave Hansen <dave@xxxxxxxx> > Cc: Rik van Riel <riel@xxxxxxxxxx> > Cc: Dmitry Adamushko <dmitry.adamushko@xxxxxxxxx> > Cc: Neil Brown <neilb@xxxxxxx> > Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx> > Cc: Mike Hommey <mh@xxxxxxxxxxxx> > Cc: Taras Glek <tglek@xxxxxxxxxxx> > Cc: Jan Kara <jack@xxxxxxx> > Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxx> > Cc: Michel Lespinasse <walken@xxxxxxxxxx> > Cc: Minchan Kim <minchan@xxxxxxxxxx> > Cc: linux-mm@xxxxxxxxx <linux-mm@xxxxxxxxx> > Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx> Just one minor nit below. Otherwise the patch looks good to me. So you can add Acked-by: Jan Kara <jack@xxxxxxx> Honza > --- > include/linux/swap.h | 15 ++++++++-- > include/linux/swapops.h | 10 +++++++ > include/linux/vrange.h | 3 ++ > mm/vrange.c | 75 +++++++++++++++++++++++++++++++++++++++++++++++++ > 4 files changed, 101 insertions(+), 2 deletions(-) > > diff --git a/include/linux/swap.h b/include/linux/swap.h > index 46ba0c6..18c12f9 100644 > --- a/include/linux/swap.h > +++ b/include/linux/swap.h > @@ -70,8 +70,19 @@ static inline int current_is_kswapd(void) > #define SWP_HWPOISON_NUM 0 > #endif > > -#define MAX_SWAPFILES \ > - ((1 << MAX_SWAPFILES_SHIFT) - SWP_MIGRATION_NUM - SWP_HWPOISON_NUM) > + > +/* > + * Purged volatile range pages > + */ > +#define SWP_VRANGE_PURGED_NUM 1 > +#define SWP_VRANGE_PURGED (MAX_SWAPFILES + SWP_HWPOISON_NUM + SWP_MIGRATION_NUM) > + > + > +#define MAX_SWAPFILES ((1 << MAX_SWAPFILES_SHIFT) \ > + - SWP_MIGRATION_NUM \ > + - SWP_HWPOISON_NUM \ > + - SWP_VRANGE_PURGED_NUM \ > + ) > > /* > * Magic header for a swap area. The first part of the union is > diff --git a/include/linux/swapops.h b/include/linux/swapops.h > index c0f7526..84f43d9 100644 > --- a/include/linux/swapops.h > +++ b/include/linux/swapops.h > @@ -161,6 +161,16 @@ static inline int is_write_migration_entry(swp_entry_t entry) > > #endif > > +static inline swp_entry_t make_vpurged_entry(void) > +{ > + return swp_entry(SWP_VRANGE_PURGED, 0); > +} > + > +static inline int is_vpurged_entry(swp_entry_t entry) > +{ > + return swp_type(entry) == SWP_VRANGE_PURGED; > +} > + > #ifdef CONFIG_MEMORY_FAILURE > /* > * Support for hardware poisoned pages > diff --git a/include/linux/vrange.h b/include/linux/vrange.h > index 6e5331e..986fa85 100644 > --- a/include/linux/vrange.h > +++ b/include/linux/vrange.h > @@ -1,6 +1,9 @@ > #ifndef _LINUX_VRANGE_H > #define _LINUX_VRANGE_H > > +#include <linux/swap.h> > +#include <linux/swapops.h> > + > #define VRANGE_NONVOLATILE 0 > #define VRANGE_VOLATILE 1 > #define VRANGE_VALID_FLAGS (0) /* Don't yet support any flags */ > diff --git a/mm/vrange.c b/mm/vrange.c > index 2f8e2ce..1ff3cbd 100644 > --- a/mm/vrange.c > +++ b/mm/vrange.c > @@ -8,6 +8,76 @@ > #include <linux/mm_inline.h> > #include "internal.h" > > +struct vrange_walker { > + struct vm_area_struct *vma; > + int page_was_purged; > +}; > + > + > +/** > + * vrange_check_purged_pte - Checks ptes for purged pages > + * > + * Iterates over the ptes in the pmd checking if they have > + * purged swap entries. > + * > + * Sets the vrange_walker.pages_purged to 1 if any were purged. ^^^ page_was_purged > + */ > +static int vrange_check_purged_pte(pmd_t *pmd, unsigned long addr, > + unsigned long end, struct mm_walk *walk) > +{ > + struct vrange_walker *vw = walk->private; > + pte_t *pte; > + spinlock_t *ptl; > + > + if (pmd_trans_huge(*pmd)) > + return 0; > + if (pmd_trans_unstable(pmd)) > + return 0; > + > + pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl); > + for (; addr != end; pte++, addr += PAGE_SIZE) { > + if (!pte_present(*pte)) { > + swp_entry_t vrange_entry = pte_to_swp_entry(*pte); > + > + if (unlikely(is_vpurged_entry(vrange_entry))) { > + vw->page_was_purged = 1; > + break; > + } > + } > + } > + pte_unmap_unlock(pte - 1, ptl); > + cond_resched(); > + > + return 0; > +} > + > + > +/** > + * vrange_check_purged - Sets up a mm_walk to check for purged pages > + * > + * Sets up and calls wa_page_range() to check for purge pages. > + * > + * Returns 1 if pages in the range were purged, 0 otherwise. > + */ > +static int vrange_check_purged(struct mm_struct *mm, > + struct vm_area_struct *vma, > + unsigned long start, > + unsigned long end) > +{ > + struct vrange_walker vw; > + struct mm_walk vrange_walk = { > + .pmd_entry = vrange_check_purged_pte, > + .mm = vma->vm_mm, > + .private = &vw, > + }; > + vw.page_was_purged = 0; > + vw.vma = vma; > + > + walk_page_range(start, end, &vrange_walk); > + > + return vw.page_was_purged; > + > +} > > /** > * do_vrange - Marks or clears VMAs in the range (start-end) as VM_VOLATILE > @@ -106,6 +176,11 @@ success: > vma = prev->vm_next; > } > out: > + if (count && (mode == VRANGE_NONVOLATILE)) > + *purged = vrange_check_purged(mm, vma, > + orig_start, > + orig_start+count); > + > up_read(&mm->mmap_sem); > > /* report bytes successfully marked, even if we're exiting on error */ > -- > 1.8.3.2 > -- Jan Kara <jack@xxxxxxx> SUSE Labs, CR -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. 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