The patch titled mmap: fix and tidy up overcommit page arithmetic has been added to the -mm tree. Its filename is mmap-fix-and-tidy-up-overcommit-page-arithmetic.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: mmap: fix and tidy up overcommit page arithmetic From: Dmitry Fink <dmitry.fink@xxxxxxxx> - shmem pages are not immediately available, but they are not potentially available either, even if we swap them out, they will just relocate from memory into swap, total amount of immediate and potentially available memory is not going to be affected, so we shouldn't count them as potentially free in the first place. - nr_free_pages() is not an expensive operation anymore, there is no need to split the decision making in two halves and repeat code. Signed-off-by: Dmitry Fink <dmitry.fink@xxxxxxxx> Reviewed-by: Minchan Kim <minchan.kim@xxxxxxxxx> Acked-by: Hugh Dickins <hughd@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/mmap.c | 34 +++++++++++++--------------------- mm/nommu.c | 34 +++++++++++++--------------------- 2 files changed, 26 insertions(+), 42 deletions(-) diff -puN mm/mmap.c~mmap-fix-and-tidy-up-overcommit-page-arithmetic mm/mmap.c --- a/mm/mmap.c~mmap-fix-and-tidy-up-overcommit-page-arithmetic +++ a/mm/mmap.c @@ -122,9 +122,17 @@ int __vm_enough_memory(struct mm_struct return 0; if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) { - unsigned long n; + free = global_page_state(NR_FREE_PAGES); + free += global_page_state(NR_FILE_PAGES); + + /* + * shmem pages shouldn't be counted as free in this + * case, they can't be purged, only swapped out, and + * that won't affect the overall amount of available + * memory in the system. + */ + free -= global_page_state(NR_SHMEM); - free = global_page_state(NR_FILE_PAGES); free += nr_swap_pages; /* @@ -136,34 +144,18 @@ int __vm_enough_memory(struct mm_struct free += global_page_state(NR_SLAB_RECLAIMABLE); /* - * Leave the last 3% for root - */ - if (!cap_sys_admin) - free -= free / 32; - - if (free > pages) - return 0; - - /* - * nr_free_pages() is very expensive on large systems, - * only call if we're about to fail. - */ - n = nr_free_pages(); - - /* * Leave reserved pages. The pages are not for anonymous pages. */ - if (n <= totalreserve_pages) + if (free <= totalreserve_pages) goto error; else - n -= totalreserve_pages; + free -= totalreserve_pages; /* * Leave the last 3% for root */ if (!cap_sys_admin) - n -= n / 32; - free += n; + free -= free / 32; if (free > pages) return 0; diff -puN mm/nommu.c~mmap-fix-and-tidy-up-overcommit-page-arithmetic mm/nommu.c --- a/mm/nommu.c~mmap-fix-and-tidy-up-overcommit-page-arithmetic +++ a/mm/nommu.c @@ -1884,9 +1884,17 @@ int __vm_enough_memory(struct mm_struct return 0; if (sysctl_overcommit_memory == OVERCOMMIT_GUESS) { - unsigned long n; + free = global_page_state(NR_FREE_PAGES); + free += global_page_state(NR_FILE_PAGES); + + /* + * shmem pages shouldn't be counted as free in this + * case, they can't be purged, only swapped out, and + * that won't affect the overall amount of available + * memory in the system. + */ + free -= global_page_state(NR_SHMEM); - free = global_page_state(NR_FILE_PAGES); free += nr_swap_pages; /* @@ -1898,34 +1906,18 @@ int __vm_enough_memory(struct mm_struct free += global_page_state(NR_SLAB_RECLAIMABLE); /* - * Leave the last 3% for root - */ - if (!cap_sys_admin) - free -= free / 32; - - if (free > pages) - return 0; - - /* - * nr_free_pages() is very expensive on large systems, - * only call if we're about to fail. - */ - n = nr_free_pages(); - - /* * Leave reserved pages. The pages are not for anonymous pages. */ - if (n <= totalreserve_pages) + if (free <= totalreserve_pages) goto error; else - n -= totalreserve_pages; + free -= totalreserve_pages; /* * Leave the last 3% for root */ if (!cap_sys_admin) - n -= n / 32; - free += n; + free -= free / 32; if (free > pages) return 0; _ Patches currently in -mm which might be from dmitry.fink@xxxxxxxx are mmap-fix-and-tidy-up-overcommit-page-arithmetic.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html