From mboxrd@z Thu Jan 1 00:00:00 1970 From: Helge Deller Date: Mon, 13 Jul 2015 18:52:37 +0000 Subject: Re: [PATCH] parisc: mm: Fix a memory leak related to pmd not attached to the pgd Message-Id: <55A408F5.601@gmx.de> List-Id: References: <1436779963-4286-1-git-send-email-christophe.jaillet@wanadoo.fr> In-Reply-To: <1436779963-4286-1-git-send-email-christophe.jaillet@wanadoo.fr> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Christophe JAILLET , jejb@parisc-linux.org, mpatocka@redhat.com, kirill.shutemov@linux.intel.com Cc: linux-parisc@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org, John David Anglin , Meelis Roos 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&m2999113232154&w=2 > Signed-off-by: Christophe JAILLET Acked-by: Helge Deller 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); > } > >