Re: [PATCH] fix spurious OOM kills

Marcelo Tosatti
2004-11-17T06:06:48Z

On Wed, Nov 17, 2004 at 01:23:46AM -0800, Andrew Morton wrote:
> Chris Ross <chris@tebibyte.org> wrote:
> >
> > As I suspected, like a recalcitrant teenager it was sneakily waiting
> > until everyone was out then it threw a wild party with several ooms and
> > an oops. See below...
>
> That's not an oops - it's just a stack trace.
>
> > This, obviously is still without Kame's patch, just the same tree as
> > before with the one change you asked for.
>
> Please ignore the previous patch and try the below. It looks like Rik's
> analysis is correct: when the caller doesn't have the swap token it just
> cannot reclaim referenced pages and scans its way into an oom. Defeating
> that logic when we've hit the highest scanning priority does seem to fix
> the problem and those nice qsbench numbers which the thrashing control gave
> us appear to be unaffected.

Oh, this fixes my testcase, and was the reason for the hog slow speed.

Excellent, wasted several days in vain. :(

> diff -puN mm/vmscan.c~vmscan-ignore-swap-token-when-in-trouble mm/vmscan.c
> --- 25/mm/vmscan.c~vmscan-ignore-swap-token-when-in-trouble 2004-11-16 20:30:00.000000000 -0800
> +++ 25-akpm/mm/vmscan.c 2004-11-16 20:30:00.000000000 -0800
> @@ -380,7 +380,7 @@ static int shrink_list(struct list_head
> if (page_mapped(page) || PageSwapCache(page))
> sc->nr_scanned++;
>
> - referenced = page_referenced(page, 1);
> + referenced = page_referenced(page, 1, sc->priority <= 0);
> /* In active use or really unfreeable? Activate it. */
> if (referenced && page_mapping_inuse(page))
> goto activate_locked;
> @@ -724,7 +724,7 @@ refill_inactive_zone(struct zone *zone,
> if (page_mapped(page)) {
> if (!reclaim_mapped ||
> (total_swap_pages == 0 && PageAnon(page)) ||
> - page_referenced(page, 0)) {
> + page_referenced(page, 0, sc->priority <= 0)) {
> list_add(&page->lru, &l_active);
> continue;
> }
> diff -puN mm/rmap.c~vmscan-ignore-swap-token-when-in-trouble mm/rmap.c
> --- 25/mm/rmap.c~vmscan-ignore-swap-token-when-in-trouble 2004-11-16 20:30:00.000000000 -0800
> +++ 25-akpm/mm/rmap.c 2004-11-16 20:30:00.000000000 -0800
> @@ -248,7 +248,7 @@ unsigned long page_address_in_vma(struct
> * repeatedly from either page_referenced_anon or page_referenced_file.
> */
> static int page_referenced_one(struct page *page,
> - struct vm_area_struct *vma, unsigned int *mapcount)
> + struct vm_area_struct *vma, unsigned int *mapcount, int ignore_token)
> {
> struct mm_struct *mm = vma->vm_mm;
> unsigned long address;
> @@ -288,7 +288,7 @@ static int page_referenced_one(struct pa
> if (ptep_clear_flush_young(vma, address, pte))
> referenced++;
>
> - if (mm != current->mm && has_swap_token(mm))
> + if (mm != current->mm && !ignore_token && has_swap_token(mm))
> referenced++;
>
> (*mapcount)--;
> @@ -301,7 +301,7 @@ out:
> return referenced;
> }
>
> -static int page_referenced_anon(struct page *page)
> +static int page_referenced_anon(struct page *page, int ignore_token)
> {
> unsigned int mapcount;
> struct anon_vma *anon_vma;
> @@ -314,7 +314,8 @@ static int page_referenced_anon(struct p
>
> mapcount = page_mapcount(page);
> list_for_each_entry(vma, &anon_vma->head, anon_vma_node) {
> - referenced += page_referenced_one(page, vma, &mapcount);
> + referenced += page_referenced_one(page, vma, &mapcount,
> + ignore_token);
> if (!mapcount)
> break;
> }
> @@ -333,7 +334,7 @@ static int page_referenced_anon(struct p
> *
> * This function is only called from page_referenced for object-based pages.
> */
> -static int page_referenced_file(struct page *page)
> +static int page_referenced_file(struct page *page, int ignore_token)
> {
> unsigned int mapcount;
> struct address_space *mapping = page->mapping;
> @@ -371,7 +372,8 @@ static int page_referenced_file(struct p
> referenced++;
> break;
> }
> - referenced += page_referenced_one(page, vma, &mapcount);
> + referenced += page_referenced_one(page, vma, &mapcount,
> + ignore_token);
> if (!mapcount)
> break;
> }
> @@ -388,7 +390,7 @@ static int page_referenced_file(struct p
> * Quick test_and_clear_referenced for all mappings to a page,
> * returns the number of ptes which referenced the page.
> */
> -int page_referenced(struct page *page, int is_locked)
> +int page_referenced(struct page *page, int is_locked, int ignore_token)
> {
> int referenced = 0;
>
> @@ -400,14 +402,15 @@ int page_referenced(struct page *page, i
>
> if (page_mapped(page) && page->mapping) {
> if (PageAnon(page))
> - referenced += page_referenced_anon(page);
> + referenced += page_referenced_anon(page, ignore_token);
> else if (is_locked)
> - referenced += page_referenced_file(page);
> + referenced += page_referenced_file(page, ignore_token);
> else if (TestSetPageLocked(page))
> referenced++;
> else {
> if (page->mapping)
> - referenced += page_referenced_file(page);
> + referenced += page_referenced_file(page,
> + ignore_token);
> unlock_page(page);
> }
> }
> diff -puN include/linux/rmap.h~vmscan-ignore-swap-token-when-in-trouble include/linux/rmap.h
> --- 25/include/linux/rmap.h~vmscan-ignore-swap-token-when-in-trouble 2004-11-16 20:30:00.000000000 -0800
> +++ 25-akpm/include/linux/rmap.h 2004-11-16 20:30:00.000000000 -0800
> @@ -89,7 +89,7 @@ static inline void page_dup_rmap(struct
> /*
> * Called from mm/vmscan.c to handle paging out
> */
> -int page_referenced(struct page *, int is_locked);
> +int page_referenced(struct page *, int is_locked, int ignore_token);
> int try_to_unmap(struct page *);
>
> /*
> @@ -103,7 +103,7 @@ unsigned long page_address_in_vma(struct
> #define anon_vma_prepare(vma) (0)
> #define anon_vma_link(vma) do {} while (0)
>
> -#define page_referenced(page,l) TestClearPageReferenced(page)
> +#define page_referenced(page,l,i) TestClearPageReferenced(page)
> #define try_to_unmap(page) SWAP_FAIL
>
> #endif /* CONFIG_MMU */
> _