From: David Rientjes <rientjes@xxxxxxxxxx> Subject: mm, shmem: add vmstat for hugepage fallback The existing thp_fault_fallback indicates when thp attempts to allocate a hugepage but fails, or if the hugepage cannot be charged to the mem cgroup hierarchy. Extend this to shmem as well. Adds a new thp_file_fallback to complement thp_file_alloc that gets incremented when a hugepage is attempted to be allocated but fails, or if it cannot be charged to the mem cgroup hierarchy. Additionally, remove the check for CONFIG_TRANSPARENT_HUGE_PAGECACHE from shmem_alloc_hugepage() since it is only called with this configuration option. Link: http://lkml.kernel.org/r/alpine.DEB.2.21.2003061421240.7412@xxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx> Reviewed-by: Yang Shi <yang.shi@xxxxxxxxxxxxxxxxx> Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> Cc: Mike Rapoport <rppt@xxxxxxxxxxxxx> Cc: Jeremy Cline <jcline@xxxxxxxxxx> Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx> Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxxxx> Cc: Vlastimil Babka <vbabka@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- Documentation/admin-guide/mm/transhuge.rst | 4 ++++ include/linux/vm_event_item.h | 2 ++ mm/shmem.c | 10 ++++++---- mm/vmstat.c | 1 + 4 files changed, 13 insertions(+), 4 deletions(-) --- a/Documentation/admin-guide/mm/transhuge.rst~mm-shmem-add-vmstat-for-hugepage-fallback +++ a/Documentation/admin-guide/mm/transhuge.rst @@ -319,6 +319,10 @@ thp_file_alloc is incremented every time a file huge page is successfully allocated. +thp_file_fallback + is incremented if a file huge page is attempted to be allocated + but fails and instead falls back to using small pages. + thp_file_mapped is incremented every time a file huge page is mapped into user address space. --- a/include/linux/vm_event_item.h~mm-shmem-add-vmstat-for-hugepage-fallback +++ a/include/linux/vm_event_item.h @@ -76,6 +76,7 @@ enum vm_event_item { PGPGIN, PGPGOUT, PS THP_COLLAPSE_ALLOC, THP_COLLAPSE_ALLOC_FAILED, THP_FILE_ALLOC, + THP_FILE_FALLBACK, THP_FILE_MAPPED, THP_SPLIT_PAGE, THP_SPLIT_PAGE_FAILED, @@ -115,6 +116,7 @@ enum vm_event_item { PGPGIN, PGPGOUT, PS #ifndef CONFIG_TRANSPARENT_HUGEPAGE #define THP_FILE_ALLOC ({ BUILD_BUG(); 0; }) +#define THP_FILE_FALLBACK ({ BUILD_BUG(); 0; }) #define THP_FILE_MAPPED ({ BUILD_BUG(); 0; }) #endif --- a/mm/shmem.c~mm-shmem-add-vmstat-for-hugepage-fallback +++ a/mm/shmem.c @@ -1472,9 +1472,6 @@ static struct page *shmem_alloc_hugepage pgoff_t hindex; struct page *page; - if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE)) - return NULL; - hindex = round_down(index, HPAGE_PMD_NR); if (xa_find(&mapping->i_pages, &hindex, hindex + HPAGE_PMD_NR - 1, XA_PRESENT)) @@ -1486,6 +1483,8 @@ static struct page *shmem_alloc_hugepage shmem_pseudo_vma_destroy(&pvma); if (page) prep_transhuge_page(page); + else + count_vm_event(THP_FILE_FALLBACK); return page; } @@ -1871,8 +1870,11 @@ alloc_nohuge: error = mem_cgroup_try_charge_delay(page, charge_mm, gfp, &memcg, PageTransHuge(page)); - if (error) + if (error) { + if (PageTransHuge(page)) + count_vm_event(THP_FILE_FALLBACK); goto unacct; + } error = shmem_add_to_page_cache(page, mapping, hindex, NULL, gfp & GFP_RECLAIM_MASK); if (error) { --- a/mm/vmstat.c~mm-shmem-add-vmstat-for-hugepage-fallback +++ a/mm/vmstat.c @@ -1259,6 +1259,7 @@ const char * const vmstat_text[] = { "thp_collapse_alloc", "thp_collapse_alloc_failed", "thp_file_alloc", + "thp_file_fallback", "thp_file_mapped", "thp_split_page", "thp_split_page_failed", _
