Hi Christophe,
On 13.07.2015 11:32, Christophe JAILLET wrote:
Commit 0e0da48dee8d ("parisc: mm: don't count preallocated pmds")
introduced a memory leak.
After this commit, the 'return' statement in pmd_free is executed in all
cases. Even for pmd that are not attached to the pgd.
So 'free_pages' can never be called anymore, leading to a memory leak.
That's really great!!! Thanks for spotting this!
I assume this fixes the leak which killed our debian buildds with OOM
after an uptime of 1-4 days and which only happened since kernel 4.0.
Meelis Roos reported the issue already in this thread:
http://marc.info/?l=linux-parisc&m=142999113232154&w=2
Signed-off-by: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>
Acked-by: Helge Deller <deller@xxxxxx>
Will this patch be pushed via linux-mm or another tree, if
not I can take it via the parisc tree?
Helge
---
This patch is *untested* as I don't have the hardware to test it.
This is just a guess based on the indentation, the comment in the code
and the commit log.
---
arch/parisc/include/asm/pgalloc.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/parisc/include/asm/pgalloc.h b/arch/parisc/include/asm/pgalloc.h
index 3a08eae..f66d3738 100644
--- a/arch/parisc/include/asm/pgalloc.h
+++ b/arch/parisc/include/asm/pgalloc.h
@@ -72,7 +72,7 @@ static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long address)
static inline void pmd_free(struct mm_struct *mm, pmd_t *pmd)
{
- if(pmd_flag(*pmd) & PxD_FLAG_ATTACHED)
+ if (pmd_flag(*pmd) & PxD_FLAG_ATTACHED) {
/*
* This is the permanent pmd attached to the pgd;
* cannot free it.
@@ -81,6 +81,7 @@ static inline void pmd_free(struct mm_struct *mm, pmd_t *pmd)
*/
mm_inc_nr_pmds(mm);
return;
+ }
free_pages((unsigned long)pmd, PMD_ORDER);
}
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