The patch titled tmpfs: open a window in shmem_unuse_inode has been added to the -mm tree. Its filename is tmpfs-open-a-window-in-shmem_unuse_inode.patch *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find out what to do about this ------------------------------------------------------ Subject: tmpfs: open a window in shmem_unuse_inode From: Hugh Dickins <hugh@xxxxxxxxxxx> There are a couple of reasons (patches follow) why it would be good to open a window for sleep in shmem_unuse_inode, between its search for a matching swap entry, and its handling of the entry found. shmem_unuse_inode must then use igrab to hold the inode against deletion in that window, and its corresponding iput might result in deletion: so it had better unlock_page before the iput, and might as well release the page too. Nor is there any need to hold on to shmem_swaplist_mutex once we know we'll leave the loop. So this unwinding moves from try_to_unuse and shmem_unuse into shmem_unuse_inode, in the case when it finds a match. Let try_to_unuse break on error in the shmem_unuse case, as it does in the unuse_mm case: though at this point in the series, no error to break on. Signed-off-by: Hugh Dickins <hugh@xxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/shmem.c | 57 +++++++++++++++++++++++++++++------------------- mm/swapfile.c | 23 ++++++++----------- 2 files changed, 45 insertions(+), 35 deletions(-) diff -puN mm/shmem.c~tmpfs-open-a-window-in-shmem_unuse_inode mm/shmem.c --- a/mm/shmem.c~tmpfs-open-a-window-in-shmem_unuse_inode +++ a/mm/shmem.c @@ -838,10 +838,8 @@ static int shmem_unuse_inode(struct shme if (size > SHMEM_NR_DIRECT) size = SHMEM_NR_DIRECT; offset = shmem_find_swp(entry, ptr, ptr+size); - if (offset >= 0) { - shmem_swp_balance_unmap(); + if (offset >= 0) goto found; - } if (!info->i_indirect) goto lost2; @@ -879,11 +877,11 @@ static int shmem_unuse_inode(struct shme if (size > ENTRIES_PER_PAGE) size = ENTRIES_PER_PAGE; offset = shmem_find_swp(entry, ptr, ptr+size); + shmem_swp_unmap(ptr); if (offset >= 0) { shmem_dir_unmap(dir); goto found; } - shmem_swp_unmap(ptr); } } lost1: @@ -893,10 +891,25 @@ lost2: return 0; found: idx += offset; - inode = &info->vfs_inode; - error = add_to_page_cache(page, inode->i_mapping, idx, GFP_ATOMIC); + inode = igrab(&info->vfs_inode); + spin_unlock(&info->lock); + + /* move head to start search for next from here */ + list_move_tail(&shmem_swaplist, &info->swaplist); + mutex_unlock(&shmem_swaplist_mutex); + + error = 1; + if (!inode) + goto out; + + spin_lock(&info->lock); + ptr = shmem_swp_entry(info, idx, NULL); + if (ptr && ptr->val == entry.val) + error = add_to_page_cache(page, inode->i_mapping, + idx, GFP_ATOMIC); if (error == -EEXIST) { struct page *filepage = find_get_page(inode->i_mapping, idx); + error = 1; if (filepage) { /* * There might be a more uptodate page coming down @@ -911,16 +924,18 @@ found: delete_from_swap_cache(page); set_page_dirty(page); info->flags |= SHMEM_PAGEIN; - shmem_swp_set(info, ptr + offset, 0); + shmem_swp_set(info, ptr, 0); + swap_free(entry); + error = 1; /* not an error, but entry was found */ } - shmem_swp_unmap(ptr); + if (ptr) + shmem_swp_unmap(ptr); spin_unlock(&info->lock); - /* - * Decrement swap count even when the entry is left behind: - * try_to_unuse will skip over mms, then reincrement count. - */ - swap_free(entry); - return 1; +out: + unlock_page(page); + page_cache_release(page); + iput(inode); /* allows for NULL */ + return error; } /* @@ -935,18 +950,16 @@ int shmem_unuse(swp_entry_t entry, struc mutex_lock(&shmem_swaplist_mutex); list_for_each_safe(p, next, &shmem_swaplist) { info = list_entry(p, struct shmem_inode_info, swaplist); - if (!info->swapped) + if (info->swapped) + found = shmem_unuse_inode(info, entry, page); + else list_del_init(&info->swaplist); - else if (shmem_unuse_inode(info, entry, page)) { - /* move head to start search for next from here */ - list_move_tail(&shmem_swaplist, &info->swaplist); - found = 1; - break; - } cond_resched(); + if (found) + goto out; } mutex_unlock(&shmem_swaplist_mutex); - return found; +out: return found; /* 0 or 1 or -ENOMEM */ } /* diff -puN mm/swapfile.c~tmpfs-open-a-window-in-shmem_unuse_inode mm/swapfile.c --- a/mm/swapfile.c~tmpfs-open-a-window-in-shmem_unuse_inode +++ a/mm/swapfile.c @@ -814,7 +814,7 @@ static int try_to_unuse(unsigned int typ atomic_inc(&new_start_mm->mm_users); atomic_inc(&prev_mm->mm_users); spin_lock(&mmlist_lock); - while (*swap_map > 1 && !retval && + while (*swap_map > 1 && !retval && !shmem && (p = p->next) != &start_mm->mmlist) { mm = list_entry(p, struct mm_struct, mmlist); if (!atomic_inc_not_zero(&mm->mm_users)) @@ -846,6 +846,13 @@ static int try_to_unuse(unsigned int typ mmput(start_mm); start_mm = new_start_mm; } + if (shmem) { + /* page has already been unlocked and released */ + if (shmem > 0) + continue; + retval = shmem; + break; + } if (retval) { unlock_page(page); page_cache_release(page); @@ -884,12 +891,6 @@ static int try_to_unuse(unsigned int typ * read from disk into another page. Splitting into two * pages would be incorrect if swap supported "shared * private" pages, but they are handled by tmpfs files. - * - * Note shmem_unuse already deleted a swappage from - * the swap cache, unless the move to filepage failed: - * in which case it left swappage in cache, lowered its - * swap count to pass quickly through the loops above, - * and now we must reincrement count to try again later. */ if ((*swap_map > 1) && PageDirty(page) && PageSwapCache(page)) { struct writeback_control wbc = { @@ -900,12 +901,8 @@ static int try_to_unuse(unsigned int typ lock_page(page); wait_on_page_writeback(page); } - if (PageSwapCache(page)) { - if (shmem) - swap_duplicate(entry); - else - delete_from_swap_cache(page); - } + if (PageSwapCache(page)) + delete_from_swap_cache(page); /* * So we could skip searching mms once swap count went _ Patches currently in -mm which might be from hugh@xxxxxxxxxxx are git-unionfs.patch swapin_readahead-excise-numa-bogosity.patch swapin_readahead-move-and-rearrange-args.patch swapin-needs-gfp_mask-for-loop-on-tmpfs.patch shmem-sgp_quick-and-sgp_fault-redundant.patch shmem_getpage-return-page-locked.patch shmem_file_write-is-redundant.patch swapin-fix-valid_swaphandles-defect.patch swapoff-scan-ptes-preemptibly.patch shmem-factor-out-sbi-free_inodes-manipulations.patch shmem-factor-out-sbi-free_inodes-manipulations-fix.patch tmpfs-fix-mounts-when-size-is-less-than-the-page-size.patch tmpfs-move-swap_state-stats-update.patch tmpfs-shuffle-add_to_swap_caches.patch tmpfs-move-swap-swizzling-into-shmem.patch tmpfs-allow-filepage-alongside-swappage.patch tmpfs-allocate-on-read-when-stacked.patch tmpfs-make-shmem_unuse-more-preemptible.patch tmpfs-open-a-window-in-shmem_unuse_inode.patch tmpfs-radix_tree_preloading.patch tmpfs-fix-shmem_swaplist-races.patch maps4-add-proportional-set-size-accounting-in-smaps.patch mm-dont-waste-swap-on-locked-pages.patch skip-writing-data-pages-when-inode-is-under-i_sync.patch printk-trivial-optimizations-fix.patch r-o-bind-mounts-track-number-of-mount-writer-fix-buggy-loop.patch r-o-bind-mounts-track-number-of-mount-writer-fix-buggy-loop-checkpatch-fixes.patch memcgroup-temporarily-revert-swapoff-mod.patch memory-controller-memory-accounting-v7.patch memory-controller-add-per-container-lru-and-reclaim-v7-memcgroup-fix-try_to_free-order.patch memcgroup-reinstate-swapoff-mod.patch memcgroup-fix-zone-isolation-oom.patch memcgroup-revert-swap_state-mods.patch prio_tree-debugging-patch.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