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Date: Mon, 20 Feb 2012 19:08:33 +0000
From: Tixy <tixy@...t.co.uk>
To: Ajeet Yadav <ajeet.yadav.77@...il.com>
Cc: Nicolas Pitre <nicolas.pitre@...aro.org>,
Sumit Bhattacharya <sumitb@...dia.com>,
linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
Catalin Marinas <catalin.marinas@....com>,
Russell King <linux@....linux.org.uk>
Subject: Re: [PATCH 2/2] ARM: dma-mapping: fix leak in consistent_init
On Mon, 2012-02-20 at 21:42 +0530, Ajeet Yadav wrote:
> Hi Tixy,
> Thanks for review, so what do you suggest drop or improve the patch?
>
I would say drop the patch, unless the more experienced Linux hands here
think otherwise.
--
Tixy
> With Regards,
> Ajeet Yadav
>
> On Feb 18, 2012 9:28 PM, "Tixy" <tixy@...t.co.uk> wrote:
> On Fri, 2012-02-17 at 18:39 +0530, Ajeet Yadav wrote:
> > Although the error in this case is unlikely, but logically
> > if error occurs then we leak memory.
> >
> > Signed-off-by: Ajeet Yadav <ajeet.yadav.77@...il.com>
>
> If you want to fix all the memory leaks then the page tables
> allocated
> by pte_alloc_kernel() need freeing as well, (and the pud and
> pmd
> tables?).
>
> However, if we run out of memory this early in boot, then the
> system is
> unusable anyway and it doesn't seem worth adding the extra
> code
> complexity to avoid any of these memory leaks.
>
> --
> Tixy
>
> > ---
> > arch/arm/mm/dma-mapping.c | 24 ++++++++++++------------
> > 1 files changed, 12 insertions(+), 12 deletions(-)
> >
> > diff --git a/arch/arm/mm/dma-mapping.c
> b/arch/arm/mm/dma-mapping.c
> > index 04bfa76..b8cf062 100644
> > --- a/arch/arm/mm/dma-mapping.c
> > +++ b/arch/arm/mm/dma-mapping.c
> > @@ -161,7 +161,6 @@ static struct arm_vmregion_head
> consistent_head = {
> > */
> > static int __init consistent_init(void)
> > {
> > - int ret = 0;
> > pgd_t *pgd;
> > pud_t *pud;
> > pmd_t *pmd;
> > @@ -171,7 +170,7 @@ static int __init consistent_init(void)
> > unsigned long num_ptes = (CONSISTENT_END - base) >>
> PMD_SHIFT;
> >
> > consistent_pte = kmalloc(num_ptes * sizeof(pte_t *),
> GFP_KERNEL);
> > - if (!consistent_pte) {
> > + if (unlikely(!consistent_pte)) {
> > pr_err("%s: no memory\n", __func__);
> > return -ENOMEM;
> > }
> > @@ -183,32 +182,33 @@ static int __init
> consistent_init(void)
> > pgd = pgd_offset(&init_mm, base);
> >
> > pud = pud_alloc(&init_mm, pgd, base);
> > - if (!pud) {
> > + if (unlikely(!pud)) {
> > printk(KERN_ERR "%s: no pud tables\n",
> __func__);
> > - ret = -ENOMEM;
> > - break;
> > + goto err;
> > }
> >
> > pmd = pmd_alloc(&init_mm, pud, base);
> > - if (!pmd) {
> > + if (unlikely(!pmd)) {
> > printk(KERN_ERR "%s: no pmd tables\n",
> __func__);
> > - ret = -ENOMEM;
> > - break;
> > + goto err;
> > }
> > WARN_ON(!pmd_none(*pmd));
> >
> > pte = pte_alloc_kernel(pmd, base);
> > - if (!pte) {
> > + if (unlikely(!pte)) {
> > printk(KERN_ERR "%s: no pte tables\n",
> __func__);
> > - ret = -ENOMEM;
> > - break;
> > + goto err;
> > }
> >
> > consistent_pte[i++] = pte;
> > base += PMD_SIZE;
> > } while (base < CONSISTENT_END);
> >
> > - return ret;
> > + return 0;
> > +err:
> > + kfree(consistent_pte);
> > + consistent_pte = NULL;
> > + return -ENOMEM;
> > }
> >
> > core_initcall(consistent_init);
>
>
>
--
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