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    Subject[PATCH] mm->rss is modified without page_table_lock held
    Hi.

    The following patch moves the page_table_lock in mm/* to cover the
    modification of mm->rss in 240-test12-pre7. It was inspired by a
    similar patch from davej(?) which covered too much, AFAIR. The item
    is on Tytso's ToDo list.

    Please comment.


    diff -Naur linux-240-t12-pre7-clean/mm/memory.c linux/mm/memory.c
    --- linux-240-t12-pre7-clean/mm/memory.c Fri Dec 8 00:45:04 2000
    +++ linux/mm/memory.c Fri Dec 8 00:48:26 2000
    @@ -371,7 +371,6 @@
    address = (address + PGDIR_SIZE) & PGDIR_MASK;
    dir++;
    } while (address && (address < end));
    - spin_unlock(&mm->page_table_lock);
    /*
    * Update rss for the mm_struct (not necessarily current->mm)
    * Notice that rss is an unsigned long.
    @@ -380,6 +379,7 @@
    mm->rss -= freed;
    else
    mm->rss = 0;
    + spin_unlock(&mm->page_table_lock);
    }


    @@ -1076,7 +1076,9 @@
    flush_icache_page(vma, page);
    }

    + spin_lock(&mm->page_table_lock);
    mm->rss++;
    + spin_unlock(&mm->page_table_lock);

    pte = mk_pte(page, vma->vm_page_prot);

    @@ -1110,7 +1112,9 @@
    return -1;
    clear_user_highpage(page, addr);
    entry = pte_mkwrite(pte_mkdirty(mk_pte(page, vma->vm_page_prot)));
    + spin_lock(&mm->page_table_lock);
    mm->rss++;
    + spin_unlock(&mm->page_table_lock);
    flush_page_to_ram(page);
    }
    set_pte(page_table, entry);
    @@ -1149,7 +1153,9 @@
    return 0;
    if (new_page == NOPAGE_OOM)
    return -1;
    + spin_lock(&mm->page_table_lock);
    ++mm->rss;
    + spin_unlock(&mm->page_table_lock);
    /*
    * This silly early PAGE_DIRTY setting removes a race
    * due to the bad i386 page protection. But it's valid
    diff -Naur linux-240-t12-pre7-clean/mm/mmap.c linux/mm/mmap.c
    --- linux-240-t12-pre7-clean/mm/mmap.c Wed Nov 22 22:41:45 2000
    +++ linux/mm/mmap.c Fri Dec 8 00:48:26 2000
    @@ -889,8 +889,8 @@
    spin_lock(&mm->page_table_lock);
    mpnt = mm->mmap;
    mm->mmap = mm->mmap_avl = mm->mmap_cache = NULL;
    - spin_unlock(&mm->page_table_lock);
    mm->rss = 0;
    + spin_unlock(&mm->page_table_lock);
    mm->total_vm = 0;
    mm->locked_vm = 0;
    while (mpnt) {
    diff -Naur linux-240-t12-pre7-clean/mm/swapfile.c linux/mm/swapfile.c
    --- linux-240-t12-pre7-clean/mm/swapfile.c Sat Nov 4 23:27:17 2000
    +++ linux/mm/swapfile.c Fri Dec 8 00:48:26 2000
    @@ -231,7 +231,9 @@
    set_pte(dir, pte_mkdirty(mk_pte(page, vma->vm_page_prot)));
    swap_free(entry);
    get_page(page);
    + spin_lock(&vma->vm_mm->page_table_lock);
    ++vma->vm_mm->rss;
    + spin_unlock(&vma->vm_mm->page_table_lock);
    }

    static inline void unuse_pmd(struct vm_area_struct * vma, pmd_t *dir,
    diff -Naur linux-240-t12-pre7-clean/mm/vmscan.c linux/mm/vmscan.c
    --- linux-240-t12-pre7-clean/mm/vmscan.c Fri Dec 8 00:45:04 2000
    +++ linux/mm/vmscan.c Fri Dec 8 00:48:26 2000
    @@ -98,7 +98,9 @@
    set_pte(page_table, swp_entry_to_pte(entry));
    drop_pte:
    UnlockPage(page);
    + spin_lock(&mm->page_table_lock);
    mm->rss--;
    + spin_unlock(&mm->page_table_lock);
    flush_tlb_page(vma, address);
    deactivate_page(page);
    page_cache_release(page);
    --
    Regards,
    Rasmus(rasmus@jaquet.dk)

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