On Sat, Apr 17, 2021 at 9:44 PM <Peter.Enderborg@xxxxxxxx> wrote:
>
> On 4/17/21 3:07 PM, Muchun Song wrote:
> > On Sat, Apr 17, 2021 at 6:41 PM Peter Enderborg
> > <peter.enderborg@xxxxxxxx> wrote:
> >> This adds a total used dma-buf memory. Details
> >> can be found in debugfs, however it is not for everyone
> >> and not always available. dma-buf are indirect allocated by
> >> userspace. So with this value we can monitor and detect
> >> userspace applications that have problems.
> >>
> >> Signed-off-by: Peter Enderborg <peter.enderborg@xxxxxxxx>
> >> ---
> >> drivers/dma-buf/dma-buf.c | 13 +++++++++++++
> >> fs/proc/meminfo.c | 5 ++++-
> >> include/linux/dma-buf.h | 1 +
> >> 3 files changed, 18 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
> >> index f264b70c383e..197e5c45dd26 100644
> >> --- a/drivers/dma-buf/dma-buf.c
> >> +++ b/drivers/dma-buf/dma-buf.c
> >> @@ -37,6 +37,7 @@ struct dma_buf_list {
> >> };
> >>
> >> static struct dma_buf_list db_list;
> >> +static atomic_long_t dma_buf_global_allocated;
> >>
> >> static char *dmabuffs_dname(struct dentry *dentry, char *buffer, int buflen)
> >> {
> >> @@ -79,6 +80,7 @@ static void dma_buf_release(struct dentry *dentry)
> >> if (dmabuf->resv == (struct dma_resv *)&dmabuf[1])
> >> dma_resv_fini(dmabuf->resv);
> >>
> >> + atomic_long_sub(dmabuf->size, &dma_buf_global_allocated);
> >> module_put(dmabuf->owner);
> >> kfree(dmabuf->name);
> >> kfree(dmabuf);
> >> @@ -586,6 +588,7 @@ struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info)
> >> mutex_lock(&db_list.lock);
> >> list_add(&dmabuf->list_node, &db_list.head);
> >> mutex_unlock(&db_list.lock);
> >> + atomic_long_add(dmabuf->size, &dma_buf_global_allocated);
> >>
> >> return dmabuf;
> >>
> >> @@ -1346,6 +1349,16 @@ void dma_buf_vunmap(struct dma_buf *dmabuf, struct dma_buf_map *map)
> >> }
> >> EXPORT_SYMBOL_GPL(dma_buf_vunmap);
> >>
> >> +/**
> >> + * dma_buf_allocated_pages - Return the used nr of pages
> >> + * allocated for dma-buf
> >> + */
> >> +long dma_buf_allocated_pages(void)
> >> +{
> >> + return atomic_long_read(&dma_buf_global_allocated) >> PAGE_SHIFT;
> >> +}
> >> +EXPORT_SYMBOL_GPL(dma_buf_allocated_pages);
> > dma_buf_allocated_pages is only called from fs/proc/meminfo.c.
> > I am confused why it should be exported. If it won't be called
> > from the driver module, we should not export it.
>
> Ah. I thought you did not want the GPL restriction. I don't have real
> opinion about it. It's written to be following the rest of the module.
> It is not needed for the usage of dma-buf in kernel module. But I
> don't see any reason for hiding it either.
The modules do not need dma_buf_allocated_pages, hiding it
can prevent the module from calling it. So I think that
EXPORT_SYMBOL_GPL is unnecessary. If one day someone
want to call it from the module, maybe it’s not too late to export
it at that time.
>
>
> > Thanks.
> >
> >> +
> >> #ifdef CONFIG_DEBUG_FS
> >> static int dma_buf_debug_show(struct seq_file *s, void *unused)
> >> {
> >> diff --git a/fs/proc/meminfo.c b/fs/proc/meminfo.c
> >> index 6fa761c9cc78..ccc7c40c8db7 100644
> >> --- a/fs/proc/meminfo.c
> >> +++ b/fs/proc/meminfo.c
> >> @@ -16,6 +16,7 @@
> >> #ifdef CONFIG_CMA
> >> #include <linux/cma.h>
> >> #endif
> >> +#include <linux/dma-buf.h>
> >> #include <asm/page.h>
> >> #include "internal.h"
> >>
> >> @@ -145,7 +146,9 @@ static int meminfo_proc_show(struct seq_file *m, void *v)
> >> show_val_kb(m, "CmaFree: ",
> >> global_zone_page_state(NR_FREE_CMA_PAGES));
> >> #endif
> >> -
> >> +#ifdef CONFIG_DMA_SHARED_BUFFER
> >> + show_val_kb(m, "DmaBufTotal: ", dma_buf_allocated_pages());
> >> +#endif
> >> hugetlb_report_meminfo(m);
> >>
> >> arch_report_meminfo(m);
> >> diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
> >> index efdc56b9d95f..5b05816bd2cd 100644
> >> --- a/include/linux/dma-buf.h
> >> +++ b/include/linux/dma-buf.h
> >> @@ -507,4 +507,5 @@ int dma_buf_mmap(struct dma_buf *, struct vm_area_struct *,
> >> unsigned long);
> >> int dma_buf_vmap(struct dma_buf *dmabuf, struct dma_buf_map *map);
> >> void dma_buf_vunmap(struct dma_buf *dmabuf, struct dma_buf_map *map);
> >> +long dma_buf_allocated_pages(void);
> >> #endif /* __DMA_BUF_H__ */
> >> --
> >> 2.17.1
> >>
