| Message ID | 20201110151444.20662-7-rppt@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | mm: introduce memfd_secret system call to create "secret" memory areas | expand |
On Tue, 10 Nov 2020 17:14:41 +0200 Mike Rapoport <rppt@kernel.org> wrote: > Account memory consumed by secretmem to memcg. The accounting is updated > when the memory is actually allocated and freed. From: Andrew Morton <akpm@linux-foundation.org> Subject: secretmem-add-memcg-accounting-fix fix CONFIG_MEMCG=n build Cc: Mike Rapoport <rppt@linux.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> --- mm/filemap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/mm/filemap.c~secretmem-add-memcg-accounting-fix +++ a/mm/filemap.c @@ -844,7 +844,7 @@ static noinline int __add_to_page_cache_ page->mapping = mapping; page->index = offset; - if (!huge && !page->memcg_data) { + if (!huge && !page_memcg(page)) { error = mem_cgroup_charge(page, current->mm, gfp); if (error) goto error;
вт, 10 нояб. 2020 г. в 07:16, Mike Rapoport <rppt@kernel.org>: > > From: Mike Rapoport <rppt@linux.ibm.com> > > Account memory consumed by secretmem to memcg. The accounting is updated > when the memory is actually allocated and freed. > > Signed-off-by: Mike Rapoport <rppt@linux.ibm.com> > --- > mm/filemap.c | 2 +- > mm/secretmem.c | 42 +++++++++++++++++++++++++++++++++++++++++- > 2 files changed, 42 insertions(+), 2 deletions(-) > > diff --git a/mm/filemap.c b/mm/filemap.c > index 249cf489f5df..11387a077373 100644 > --- a/mm/filemap.c > +++ b/mm/filemap.c > @@ -844,7 +844,7 @@ static noinline int __add_to_page_cache_locked(struct page *page, > page->mapping = mapping; > page->index = offset; > > - if (!huge) { > + if (!huge && !page->memcg_data) { > error = mem_cgroup_charge(page, current->mm, gfp); > if (error) > goto error; > diff --git a/mm/secretmem.c b/mm/secretmem.c > index 1aa2b7cffe0d..1eb7667016fa 100644 > --- a/mm/secretmem.c > +++ b/mm/secretmem.c > @@ -17,6 +17,7 @@ > #include <linux/syscalls.h> > #include <linux/memblock.h> > #include <linux/pseudo_fs.h> > +#include <linux/memcontrol.h> > #include <linux/set_memory.h> > #include <linux/sched/signal.h> > > @@ -49,6 +50,38 @@ struct secretmem_ctx { > > static struct cma *secretmem_cma; > Hi Mike! > +static int secretmem_memcg_charge(struct page *page, gfp_t gfp, int order) > +{ > + unsigned long nr_pages = (1 << order); > + int i, err; > + > + err = memcg_kmem_charge_page(page, gfp, order); > + if (err) > + return err; > + > + for (i = 1; i < nr_pages; i++) { > + struct page *p = page + i; > + > + p->memcg_data = page->memcg_data; > + } Hm, it looks very strange to me. Why do we need to copy memcg_data? What about css reference counting? And what about statistics? I'm sorry for being late. Thank you! > + > + return 0; > +} > + > +static void secretmem_memcg_uncharge(struct page *page, int order) > +{ > + unsigned long nr_pages = (1 << order); > + int i; > + > + for (i = 1; i < nr_pages; i++) { > + struct page *p = page + i; > + > + p->memcg_data = 0; > + } > + > + memcg_kmem_uncharge_page(page, PMD_PAGE_ORDER); > +} > + > static int secretmem_pool_increase(struct secretmem_ctx *ctx, gfp_t gfp) > { > unsigned long nr_pages = (1 << PMD_PAGE_ORDER); > @@ -61,10 +94,14 @@ static int secretmem_pool_increase(struct secretmem_ctx *ctx, gfp_t gfp) > if (!page) > return -ENOMEM; > > - err = set_direct_map_invalid_noflush(page, nr_pages); > + err = secretmem_memcg_charge(page, gfp, PMD_PAGE_ORDER); > if (err) > goto err_cma_release; > > + err = set_direct_map_invalid_noflush(page, nr_pages); > + if (err) > + goto err_memcg_uncharge; > + > addr = (unsigned long)page_address(page); > err = gen_pool_add(pool, addr, PMD_SIZE, NUMA_NO_NODE); > if (err) > @@ -81,6 +118,8 @@ static int secretmem_pool_increase(struct secretmem_ctx *ctx, gfp_t gfp) > * won't fail > */ > set_direct_map_default_noflush(page, nr_pages); > +err_memcg_uncharge: > + secretmem_memcg_uncharge(page, PMD_PAGE_ORDER); > err_cma_release: > cma_release(secretmem_cma, page, nr_pages); > return err; > @@ -310,6 +349,7 @@ static void secretmem_cleanup_chunk(struct gen_pool *pool, > int i; > > set_direct_map_default_noflush(page, nr_pages); > + secretmem_memcg_uncharge(page, PMD_PAGE_ORDER); > > for (i = 0; i < nr_pages; i++) > clear_highpage(page + i); > -- > 2.28.0 > >
On Fri, Nov 13, 2020 at 03:42:25PM -0800, Roman Gushchin wrote: > вт, 10 нояб. 2020 г. в 07:16, Mike Rapoport <rppt@kernel.org>: > > > > From: Mike Rapoport <rppt@linux.ibm.com> > > > > Account memory consumed by secretmem to memcg. The accounting is updated > > when the memory is actually allocated and freed. > > > > Signed-off-by: Mike Rapoport <rppt@linux.ibm.com> > > --- > > mm/filemap.c | 2 +- > > mm/secretmem.c | 42 +++++++++++++++++++++++++++++++++++++++++- > > 2 files changed, 42 insertions(+), 2 deletions(-) > > > > diff --git a/mm/filemap.c b/mm/filemap.c > > index 249cf489f5df..11387a077373 100644 > > --- a/mm/filemap.c > > +++ b/mm/filemap.c > > @@ -844,7 +844,7 @@ static noinline int __add_to_page_cache_locked(struct page *page, > > page->mapping = mapping; > > page->index = offset; > > > > - if (!huge) { > > + if (!huge && !page->memcg_data) { > > error = mem_cgroup_charge(page, current->mm, gfp); > > if (error) > > goto error; > > diff --git a/mm/secretmem.c b/mm/secretmem.c > > index 1aa2b7cffe0d..1eb7667016fa 100644 > > --- a/mm/secretmem.c > > +++ b/mm/secretmem.c > > @@ -17,6 +17,7 @@ > > #include <linux/syscalls.h> > > #include <linux/memblock.h> > > #include <linux/pseudo_fs.h> > > +#include <linux/memcontrol.h> > > #include <linux/set_memory.h> > > #include <linux/sched/signal.h> > > > > @@ -49,6 +50,38 @@ struct secretmem_ctx { > > > > static struct cma *secretmem_cma; > > > > Hi Mike! > > > +static int secretmem_memcg_charge(struct page *page, gfp_t gfp, int order) > > +{ > > + unsigned long nr_pages = (1 << order); > > + int i, err; > > + > > + err = memcg_kmem_charge_page(page, gfp, order); > > + if (err) > > + return err; > > + > > + for (i = 1; i < nr_pages; i++) { > > + struct page *p = page + i; > > + > > + p->memcg_data = page->memcg_data; > > + } > > Hm, it looks very strange to me. Why do we need to copy memcg_data? > What about css reference counting? I need to copy memcg_data to mark a page as being accounted so it won't be charged again when it is added to page cache. What happens here is that I allocate a large page and then use it as a local cache for allocations in secretmem_fault(). I charge the large page as kmem. During secretmem_fault() a small sub-page from that large page goes into page cache and there I skip its memcg accounting. In the end, when the large page is freed, the memcg_data for all its sub-pages is cleared and I uncharge memcg with the order of large page. An alternative would be to uncharge a small page from kmem in secretmem_fault() and make this page charged in add_to_page_cache(), but that would complicate the release path as I would need to re-charge the small page back to kmem at secretmem_freepage() and track all the participating memcgs till the large page is freed. > And what about statistics? Hmm, that's probably won't be accurate :-/ > I'm sorry for being late. > > Thank you! > > > + > > + return 0; > > +} > > + > > +static void secretmem_memcg_uncharge(struct page *page, int order) > > +{ > > + unsigned long nr_pages = (1 << order); > > + int i; > > + > > + for (i = 1; i < nr_pages; i++) { > > + struct page *p = page + i; > > + > > + p->memcg_data = 0; > > + } > > + > > + memcg_kmem_uncharge_page(page, PMD_PAGE_ORDER); > > +} > > + > > static int secretmem_pool_increase(struct secretmem_ctx *ctx, gfp_t gfp) > > { > > unsigned long nr_pages = (1 << PMD_PAGE_ORDER); > > @@ -61,10 +94,14 @@ static int secretmem_pool_increase(struct secretmem_ctx *ctx, gfp_t gfp) > > if (!page) > > return -ENOMEM; > > > > - err = set_direct_map_invalid_noflush(page, nr_pages); > > + err = secretmem_memcg_charge(page, gfp, PMD_PAGE_ORDER); > > if (err) > > goto err_cma_release; > > > > + err = set_direct_map_invalid_noflush(page, nr_pages); > > + if (err) > > + goto err_memcg_uncharge; > > + > > addr = (unsigned long)page_address(page); > > err = gen_pool_add(pool, addr, PMD_SIZE, NUMA_NO_NODE); > > if (err) > > @@ -81,6 +118,8 @@ static int secretmem_pool_increase(struct secretmem_ctx *ctx, gfp_t gfp) > > * won't fail > > */ > > set_direct_map_default_noflush(page, nr_pages); > > +err_memcg_uncharge: > > + secretmem_memcg_uncharge(page, PMD_PAGE_ORDER); > > err_cma_release: > > cma_release(secretmem_cma, page, nr_pages); > > return err; > > @@ -310,6 +349,7 @@ static void secretmem_cleanup_chunk(struct gen_pool *pool, > > int i; > > > > set_direct_map_default_noflush(page, nr_pages); > > + secretmem_memcg_uncharge(page, PMD_PAGE_ORDER); > > > > for (i = 0; i < nr_pages; i++) > > clear_highpage(page + i); > > -- > > 2.28.0 > > > >
diff --git a/mm/filemap.c b/mm/filemap.c index 249cf489f5df..11387a077373 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -844,7 +844,7 @@ static noinline int __add_to_page_cache_locked(struct page *page, page->mapping = mapping; page->index = offset; - if (!huge) { + if (!huge && !page->memcg_data) { error = mem_cgroup_charge(page, current->mm, gfp); if (error) goto error; diff --git a/mm/secretmem.c b/mm/secretmem.c index 1aa2b7cffe0d..1eb7667016fa 100644 --- a/mm/secretmem.c +++ b/mm/secretmem.c @@ -17,6 +17,7 @@ #include <linux/syscalls.h> #include <linux/memblock.h> #include <linux/pseudo_fs.h> +#include <linux/memcontrol.h> #include <linux/set_memory.h> #include <linux/sched/signal.h> @@ -49,6 +50,38 @@ struct secretmem_ctx { static struct cma *secretmem_cma; +static int secretmem_memcg_charge(struct page *page, gfp_t gfp, int order) +{ + unsigned long nr_pages = (1 << order); + int i, err; + + err = memcg_kmem_charge_page(page, gfp, order); + if (err) + return err; + + for (i = 1; i < nr_pages; i++) { + struct page *p = page + i; + + p->memcg_data = page->memcg_data; + } + + return 0; +} + +static void secretmem_memcg_uncharge(struct page *page, int order) +{ + unsigned long nr_pages = (1 << order); + int i; + + for (i = 1; i < nr_pages; i++) { + struct page *p = page + i; + + p->memcg_data = 0; + } + + memcg_kmem_uncharge_page(page, PMD_PAGE_ORDER); +} + static int secretmem_pool_increase(struct secretmem_ctx *ctx, gfp_t gfp) { unsigned long nr_pages = (1 << PMD_PAGE_ORDER); @@ -61,10 +94,14 @@ static int secretmem_pool_increase(struct secretmem_ctx *ctx, gfp_t gfp) if (!page) return -ENOMEM; - err = set_direct_map_invalid_noflush(page, nr_pages); + err = secretmem_memcg_charge(page, gfp, PMD_PAGE_ORDER); if (err) goto err_cma_release; + err = set_direct_map_invalid_noflush(page, nr_pages); + if (err) + goto err_memcg_uncharge; + addr = (unsigned long)page_address(page); err = gen_pool_add(pool, addr, PMD_SIZE, NUMA_NO_NODE); if (err) @@ -81,6 +118,8 @@ static int secretmem_pool_increase(struct secretmem_ctx *ctx, gfp_t gfp) * won't fail */ set_direct_map_default_noflush(page, nr_pages); +err_memcg_uncharge: + secretmem_memcg_uncharge(page, PMD_PAGE_ORDER); err_cma_release: cma_release(secretmem_cma, page, nr_pages); return err; @@ -310,6 +349,7 @@ static void secretmem_cleanup_chunk(struct gen_pool *pool, int i; set_direct_map_default_noflush(page, nr_pages); + secretmem_memcg_uncharge(page, PMD_PAGE_ORDER); for (i = 0; i < nr_pages; i++) clear_highpage(page + i);