Messages in this thread | | | Date | Mon, 13 Jul 2015 20:52:37 +0200 | From | Helge Deller <> | Subject | Re: [PATCH] parisc: mm: Fix a memory leak related to pmd not attached to the pgd |
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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@wanadoo.fr>
Acked-by: Helge Deller <deller@gmx.de>
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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