The patch titled Subject: frontswap: get rid of swap_lock dependency has been added to the -mm tree. Its filename is frontswap-get-rid-of-swap_lock-dependency.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 *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Minchan Kim <minchan@xxxxxxxxxx> Subject: frontswap: get rid of swap_lock dependency Frontswap initialization routine depends on swap_lock, which want to be atomic about frontswap's first appearance. IOW, frontswap is not present and will fail all calls OR frontswap is fully functional but if new swap_info_struct isn't registered by enable_swap_info, swap subsystem doesn't start I/O so there is no race between init procedure and page I/O working on frontswap. So let's remove unnecessary swap_lock dependency. Cc: Dan Magenheimer <dan.magenheimer@xxxxxxxxxx> Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx> [v1: Rebased on my branch, reworked to work with backends loading late] [v2: Added a check for !map] [v3: Made the invalidate path follow the init path] [v4: Address comments by Wanpeng Li <liwanp@xxxxxxxxxxxxxxxxxx>] Signed-off-by: Konrad Rzeszutek Wilk <konrad@xxxxxxxxxx> Signed-off-by: Bob Liu <lliubbo@xxxxxxxxx> Cc: Wanpeng Li <liwanp@xxxxxxxxxxxxxxxxxx> Cc: Andor Daam <andor.daam@xxxxxxxxxxxxxx> Cc: Florian Schmaus <fschmaus@xxxxxxxxx> Cc: Stefan Hengelein <ilendir@xxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/frontswap.h | 6 +++--- mm/frontswap.c | 31 +++++++++++++++++++++++-------- mm/swapfile.c | 17 +++++++++-------- 3 files changed, 35 insertions(+), 19 deletions(-) diff -puN include/linux/frontswap.h~frontswap-get-rid-of-swap_lock-dependency include/linux/frontswap.h --- a/include/linux/frontswap.h~frontswap-get-rid-of-swap_lock-dependency +++ a/include/linux/frontswap.h @@ -23,7 +23,7 @@ extern void frontswap_writethrough(bool) extern void frontswap_tmem_exclusive_gets(bool); extern bool __frontswap_test(struct swap_info_struct *, pgoff_t); -extern void __frontswap_init(unsigned type); +extern void __frontswap_init(unsigned type, unsigned long *map); extern int __frontswap_store(struct page *page); extern int __frontswap_load(struct page *page); extern void __frontswap_invalidate_page(unsigned, pgoff_t); @@ -98,10 +98,10 @@ static inline void frontswap_invalidate_ __frontswap_invalidate_area(type); } -static inline void frontswap_init(unsigned type) +static inline void frontswap_init(unsigned type, unsigned long *map) { if (frontswap_enabled) - __frontswap_init(type); + __frontswap_init(type, map); } #endif /* _LINUX_FRONTSWAP_H */ diff -puN mm/frontswap.c~frontswap-get-rid-of-swap_lock-dependency mm/frontswap.c --- a/mm/frontswap.c~frontswap-get-rid-of-swap_lock-dependency +++ a/mm/frontswap.c @@ -121,8 +121,13 @@ struct frontswap_ops *frontswap_register int i; for (i = 0; i < MAX_SWAPFILES; i++) { - if (test_and_clear_bit(i, need_init)) + if (test_and_clear_bit(i, need_init)) { + struct swap_info_struct *sis = swap_info[i]; + /* __frontswap_init _should_ have set it! */ + if (!sis->frontswap_map) + return ERR_PTR(-EINVAL); ops->init(i); + } } /* * We MUST have frontswap_ops set _after_ the frontswap_init's @@ -156,20 +161,30 @@ EXPORT_SYMBOL(frontswap_tmem_exclusive_g /* * Called when a swap device is swapon'd. */ -void __frontswap_init(unsigned type) +void __frontswap_init(unsigned type, unsigned long *map) { struct swap_info_struct *sis = swap_info[type]; - if (frontswap_ops) { - BUG_ON(sis == NULL); - if (sis->frontswap_map == NULL) - return; + BUG_ON(sis == NULL); + + /* + * p->frontswap is a bitmap that we MUST have to figure out which page + * has gone in frontswap. Without it there is no point of continuing. + */ + if (WARN_ON(!map)) + return; + /* + * Irregardless of whether the frontswap backend has been loaded + * before this function or it will be later, we _MUST_ have the + * p->frontswap set to something valid to work properly. + */ + frontswap_map_set(sis, map); + if (frontswap_ops) frontswap_ops->init(type); - } else { + else { BUG_ON(type > MAX_SWAPFILES); set_bit(type, need_init); } - } EXPORT_SYMBOL(__frontswap_init); diff -puN mm/swapfile.c~frontswap-get-rid-of-swap_lock-dependency mm/swapfile.c --- a/mm/swapfile.c~frontswap-get-rid-of-swap_lock-dependency +++ a/mm/swapfile.c @@ -1509,8 +1509,7 @@ static int setup_swap_extents(struct swa } static void _enable_swap_info(struct swap_info_struct *p, int prio, - unsigned char *swap_map, - unsigned long *frontswap_map) + unsigned char *swap_map) { int i, prev; @@ -1519,7 +1518,6 @@ static void _enable_swap_info(struct swa else p->prio = --least_priority; p->swap_map = swap_map; - frontswap_map_set(p, frontswap_map); p->flags |= SWP_WRITEOK; atomic_long_add(p->pages, &nr_swap_pages); total_swap_pages += p->pages; @@ -1542,10 +1540,10 @@ static void enable_swap_info(struct swap unsigned char *swap_map, unsigned long *frontswap_map) { + frontswap_init(p->type, frontswap_map); spin_lock(&swap_lock); spin_lock(&p->lock); - _enable_swap_info(p, prio, swap_map, frontswap_map); - frontswap_init(p->type); + _enable_swap_info(p, prio, swap_map); spin_unlock(&p->lock); spin_unlock(&swap_lock); } @@ -1554,7 +1552,7 @@ static void reinsert_swap_info(struct sw { spin_lock(&swap_lock); spin_lock(&p->lock); - _enable_swap_info(p, p->prio, p->swap_map, frontswap_map_get(p)); + _enable_swap_info(p, p->prio, p->swap_map); spin_unlock(&p->lock); spin_unlock(&swap_lock); } @@ -1563,6 +1561,7 @@ SYSCALL_DEFINE1(swapoff, const char __us { struct swap_info_struct *p = NULL; unsigned char *swap_map; + unsigned long *frontswap_map; struct file *swap_file, *victim; struct address_space *mapping; struct inode *inode; @@ -1662,12 +1661,14 @@ SYSCALL_DEFINE1(swapoff, const char __us swap_map = p->swap_map; p->swap_map = NULL; p->flags = 0; - frontswap_invalidate_area(type); + frontswap_map = frontswap_map_get(p); + frontswap_map_set(p, NULL); spin_unlock(&p->lock); spin_unlock(&swap_lock); + frontswap_invalidate_area(type); mutex_unlock(&swapon_mutex); vfree(swap_map); - vfree(frontswap_map_get(p)); + vfree(frontswap_map); /* Destroy swap account informatin */ swap_cgroup_swapoff(type); _ Patches currently in -mm which might be from minchan@xxxxxxxxxx are mm-frontswap-lazy-initialization-to-allow-tmem-backends-to-build-run-as-modules.patch frontswap-make-frontswap_init-use-a-pointer-for-the-ops.patch mm-frontswap-cleanup-code.patch frontswap-get-rid-of-swap_lock-dependency.patch mm-cleancache-lazy-initialization-to-allow-tmem-backends-to-build-run-as-modules.patch cleancache-make-cleancache_init-use-a-pointer-for-the-ops.patch mm-cleancache-clean-up-cleancache_enabled.patch xen-tmem-enable-xen-tmem-shim-to-be-built-loaded-as-a-module.patch zcache-tmem-better-error-checking-on-frontswap_register_ops-return-value.patch staging-zcache-enable-ramster-to-be-built-loaded-as-a-module.patch staging-zcache-enable-zcache-to-be-built-loaded-as-a-module.patch mm-add-vm-event-counters-for-balloon-pages-compaction.patch block-aio-batch-completion-for-bios-kiocbs-fix-fix-fix-fix-fix.patch block-aio-batch-completion-for-bios-kiocbs-fix-fix-fix-fix-fix-fix.patch debugging-keep-track-of-page-owners-fix-2.patch debugging-keep-track-of-page-owners-fix-2-fix.patch debugging-keep-track-of-page-owners-fix-2-fix-fix.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