Messages in this thread Patch in this message |  | | Subject | Re: [Patch] shmem_unuse race fix | From | Christoph Rohland <> | Date | 28 Dec 2000 13:02:07 +0100 |
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Linus Torvalds <torvalds@transmeta.com> writes:
> On 27 Dec 2000, Christoph Rohland wrote: > Woul dyou mind testing this alternate fix instead:
Does not work, but is the right direction I think.
First we need the following patch since otherwise we use a swap entry without having the count increased:
--- 4-13-4/mm/vmscan.c Fri Dec 22 10:05:38 2000 +++ m4-13-4/mm/vmscan.c Thu Dec 28 11:57:57 2000 @@ -93,8 +93,8 @@ entry.val = page->index; if (pte_dirty(pte)) SetPageDirty(page); -set_swap_pte: swap_duplicate(entry); +set_swap_pte: set_pte(page_table, swp_entry_to_pte(entry)); drop_pte: UnlockPage(page); @@ -185,7 +185,7 @@ * we have the swap cache set up to associate the * page with that swap entry. */ - entry = get_swap_page(); + entry = __get_swap_page(2); if (!entry.val) goto out_unlock_restore; /* No swap space left */
Second there look at this in handle_pte_fault:
/* * If it truly wasn't present, we know that kswapd * and the PTE updates will not touch it later. So * drop the lock. */ spin_unlock(&mm->page_table_lock); if (pte_none(entry)) return do_no_page(mm, vma, address, write_access, pte); return do_swap_page(mm, vma, address, pte, pte_to_swp_entry(entry), write_access); The comment is wrong. try_to_unuse will touch it. This stumbles over a bad swap entry after try_to_unuse complaining about an undead swap entry.
If I retry in try_to_unuse it goes into an infinite loop since it deadlocks with this.
Ideas? Christoph
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