Re: [PATCH 0/8] Volatile Ranges (v8?)

[Minchan Kim]

Hello Dhaval,

On Mon, Jun 17, 2013 at 12:24:07PM -0400, Dhaval Giani wrote:
> Hi John,
> 
> I have been giving your git tree a whirl, and in order to simulate a
> limited memory environment, I was using memory cgroups.
> 
> The program I was using to test is attached here. It is your test
> code, with some changes (changing the syscall interface, reducing
> the memory pressure to be generated).
> 
> I trapped it in a memory cgroup with 1MB memory.limit_in_bytes and hit this,
> 
> [  406.207612] ------------[ cut here ]------------
> [  406.207621] kernel BUG at mm/vrange.c:523!
> [  406.207626] invalid opcode: 0000 [#1] SMP
> [  406.207631] Modules linked in:
> [  406.207637] CPU: 0 PID: 1579 Comm: volatile-test Not tainted

Thanks for the testing!
Does below patch fix your problem?

diff --git a/mm/swapfile.c b/mm/swapfile.c
index d41c63f..1f6c80e 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -751,7 +751,7 @@ int __free_swap_and_cache(swp_entry_t entry)
 			page = find_get_page(swap_address_space(entry),
 						entry.val);
 		}
-		spin_unlock(&swap_lock);
+		spin_unlock(&p->lock);
 	}
 
 	if (page) {
diff --git a/mm/vrange.c b/mm/vrange.c
index fa965fb..dc32cfa 100644
--- a/mm/vrange.c
+++ b/mm/vrange.c
@@ -485,7 +485,7 @@ int try_to_discard_one(struct vrange_root *vroot, struct page *page,
 {
 	struct mm_struct *mm = vma->vm_mm;
 	pte_t *pte;
-	pte_t pteval;
+	pte_t pteval, pteswap;
 	spinlock_t *ptl;
 	int ret = 0;
 	bool present;
@@ -505,7 +505,7 @@ int try_to_discard_one(struct vrange_root *vroot, struct page *page,
 	present = pte_present(*pte);
 	flush_cache_page(vma, address, page_to_pfn(page));
 
-	ptep_clear_flush(vma, address, pte);
+	pteswap = ptep_clear_flush(vma, address, pte);
 	pteval = pte_mkvrange(*pte);
 
 	update_hiwater_rss(mm);
@@ -517,10 +517,11 @@ int try_to_discard_one(struct vrange_root *vroot, struct page *page,
 	page_remove_rmap(page);
 	page_cache_release(page);
 	if (!present) {
-		swp_entry_t entry = pte_to_swp_entry(*pte);
+		swp_entry_t entry = pte_to_swp_entry(pteswap);
 		dec_mm_counter(mm, MM_SWAPENTS);
-		if (unlikely(!__free_swap_and_cache(entry)))
+		if (unlikely(!__free_swap_and_cache(entry))) {
 			BUG_ON(1);
+		}
 	}
 
 	set_pte_at(mm, address, pte, pteval);
-- 
1.7.9.5

-- 
Kind regards,
Minchan Kim
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