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* mm/frontswap: mark various intentional data racesQian Cai2020-08-151-4/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There are a few information counters that are intentionally not protected against increment races, so just annotate them using the data_race() macro. BUG: KCSAN: data-race in __frontswap_store / __frontswap_store write to 0xffffffff8b7174d8 of 8 bytes by task 6396 on cpu 103: __frontswap_store+0x2d0/0x344 inc_frontswap_failed_stores at mm/frontswap.c:70 (inlined by) __frontswap_store at mm/frontswap.c:280 swap_writepage+0x83/0xf0 pageout+0x33e/0xae0 shrink_page_list+0x1f57/0x2870 shrink_inactive_list+0x316/0x880 shrink_lruvec+0x8dc/0x1380 shrink_node+0x317/0xd80 do_try_to_free_pages+0x1f7/0xa10 try_to_free_pages+0x26c/0x5e0 __alloc_pages_slowpath+0x458/0x1290 __alloc_pages_nodemask+0x3bb/0x450 alloc_pages_vma+0x8a/0x2c0 do_anonymous_page+0x170/0x700 __handle_mm_fault+0xc9f/0xd00 handle_mm_fault+0xfc/0x2f0 do_page_fault+0x263/0x6f9 page_fault+0x34/0x40 read to 0xffffffff8b7174d8 of 8 bytes by task 6405 on cpu 47: __frontswap_store+0x2b9/0x344 inc_frontswap_failed_stores at mm/frontswap.c:70 (inlined by) __frontswap_store at mm/frontswap.c:280 swap_writepage+0x83/0xf0 pageout+0x33e/0xae0 shrink_page_list+0x1f57/0x2870 shrink_inactive_list+0x316/0x880 shrink_lruvec+0x8dc/0x1380 shrink_node+0x317/0xd80 do_try_to_free_pages+0x1f7/0xa10 try_to_free_pages+0x26c/0x5e0 __alloc_pages_slowpath+0x458/0x1290 __alloc_pages_nodemask+0x3bb/0x450 alloc_pages_vma+0x8a/0x2c0 do_anonymous_page+0x170/0x700 __handle_mm_fault+0xc9f/0xd00 handle_mm_fault+0xfc/0x2f0 do_page_fault+0x263/0x6f9 page_fault+0x34/0x40 Signed-off-by: Qian Cai <cai@lca.pw> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Cc: Marco Elver <elver@google.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Link: http://lkml.kernel.org/r/1581114499-5042-1-git-send-email-cai@lca.pw Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* treewide: Remove uninitialized_var() usageKees Cook2020-07-161-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Using uninitialized_var() is dangerous as it papers over real bugs[1] (or can in the future), and suppresses unrelated compiler warnings (e.g. "unused variable"). If the compiler thinks it is uninitialized, either simply initialize the variable or make compiler changes. In preparation for removing[2] the[3] macro[4], remove all remaining needless uses with the following script: git grep '\buninitialized_var\b' | cut -d: -f1 | sort -u | \ xargs perl -pi -e \ 's/\buninitialized_var\(([^\)]+)\)/\1/g; s:\s*/\* (GCC be quiet|to make compiler happy) \*/$::g;' drivers/video/fbdev/riva/riva_hw.c was manually tweaked to avoid pathological white-space. No outstanding warnings were found building allmodconfig with GCC 9.3.0 for x86_64, i386, arm64, arm, powerpc, powerpc64le, s390x, mips, sparc64, alpha, and m68k. [1] https://lore.kernel.org/lkml/20200603174714.192027-1-glider@google.com/ [2] https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/ [3] https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/ [4] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/ Reviewed-by: Leon Romanovsky <leonro@mellanox.com> # drivers/infiniband and mlx4/mlx5 Acked-by: Jason Gunthorpe <jgg@mellanox.com> # IB Acked-by: Kalle Valo <kvalo@codeaurora.org> # wireless drivers Reviewed-by: Chao Yu <yuchao0@huawei.com> # erofs Signed-off-by: Kees Cook <keescook@chromium.org>
* mm/frontswap: fix some typos in frontswap.cEthon Paul2020-06-051-3/+3
| | | | | | | | | | | | | | There are some typos in comment, fix them. s/Fortunatly/Fortunately s/taked/taken s/necessory/necessary s/shink/shrink Signed-off-by: Ethon Paul <ethp@qq.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/20200411064009.15727-1-ethp@qq.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 482Thomas Gleixner2019-06-191-2/+1
| | | | | | | | | | | | | | | | | | | Based on 1 normalized pattern(s): this work is licensed under the terms of the gnu gpl version 2 extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 48 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Allison Randal <allison@lohutok.net> Reviewed-by: Enrico Weigelt <info@metux.net> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190604081204.624030236@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* mm: use octal not symbolic permissionsJoe Perches2018-06-151-6/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | mm/*.c files use symbolic and octal styles for permissions. Using octal and not symbolic permissions is preferred by many as more readable. https://lkml.org/lkml/2016/8/2/1945 Prefer the direct use of octal for permissions. Done using $ scripts/checkpatch.pl -f --types=SYMBOLIC_PERMS --fix-inplace mm/*.c and some typing. Before: $ git grep -P -w "0[0-7]{3,3}" mm | wc -l 44 After: $ git grep -P -w "0[0-7]{3,3}" mm | wc -l 86 Miscellanea: o Whitespace neatening around these conversions. Link: http://lkml.kernel.org/r/2e032ef111eebcd4c5952bae86763b541d373469.1522102887.git.joe@perches.com Signed-off-by: Joe Perches <joe@perches.com> Acked-by: David Rientjes <rientjes@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* docs/vm: rename documentation files to .rstMike Rapoport2018-04-161-1/+1
| | | | | Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
* mm, frontswap: convert frontswap_enabled to static keyVlastimil Babka2016-07-271-20/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | I have noticed that frontswap.h first declares "frontswap_enabled" as extern bool variable, and then overrides it with "#define frontswap_enabled (1)" for CONFIG_FRONTSWAP=Y or (0) when disabled. The bool variable isn't actually instantiated anywhere. This all looks like an unfinished attempt to make frontswap_enabled reflect whether a backend is instantiated. But in the current state, all frontswap hooks call unconditionally into frontswap.c just to check if frontswap_ops is non-NULL. This should at least be checked inline, but we can further eliminate the overhead when CONFIG_FRONTSWAP is enabled and no backend registered, using a static key that is initially disabled, and gets enabled only upon first backend registration. Thus, checks for "frontswap_enabled" are replaced with "frontswap_enabled()" wrapping the static key check. There are two exceptions: - xen's selfballoon_process() was testing frontswap_enabled in code guarded by #ifdef CONFIG_FRONTSWAP, which was effectively always true when reachable. The patch just removes this check. Using frontswap_enabled() does not sound correct here, as this can be true even without xen's own backend being registered. - in SYSCALL_DEFINE2(swapon), change the check to IS_ENABLED(CONFIG_FRONTSWAP) as it seems the bitmap allocation cannot currently be postponed until a backend is registered. This means that frontswap will still have some memory overhead by being configured, but without a backend. After the patch, we can expect that some functions in frontswap.c are called only when frontswap_ops is non-NULL. Change the checks there to VM_BUG_ONs. While at it, convert other BUG_ONs to VM_BUG_ONs as frontswap has been stable for some time. [akpm@linux-foundation.org: coding-style fixes] Link: http://lkml.kernel.org/r/1463152235-9717-1-git-send-email-vbabka@suse.cz Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: David Vrabel <david.vrabel@citrix.com> Cc: Juergen Gross <jgross@suse.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* frontswap: allow multiple backendsDan Streetman2015-06-251-84/+131
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | Change frontswap single pointer to a singly linked list of frontswap implementations. Update Xen tmem implementation as register no longer returns anything. Frontswap only keeps track of a single implementation; any implementation that registers second (or later) will replace the previously registered implementation, and gets a pointer to the previous implementation that the new implementation is expected to pass all frontswap functions to if it can't handle the function itself. However that method doesn't really make much sense, as passing that work on to every implementation adds unnecessary work to implementations; instead, frontswap should simply keep a list of all registered implementations and try each implementation for any function. Most importantly, neither of the two currently existing frontswap implementations in the kernel actually do anything with any previous frontswap implementation that they replace when registering. This allows frontswap to successfully manage multiple implementations by keeping a list of them all. Signed-off-by: Dan Streetman <ddstreet@ieee.org> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: David Vrabel <david.vrabel@citrix.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/frontswap.c: fix the condition in BUG_ONLi Haifeng2014-12-111-1/+1
| | | | | | | | | | The largest index of swap device is MAX_SWAPFILES-1. So the type should be less than MAX_SWAPFILES. Signed-off-by: Haifeng Li <omycle@gmail.com> Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: frontswap: invalidate expired data on a dup-store failureWeijie Yang2014-12-031-1/+3
| | | | | | | | | | | | | | | | | | | | | | | | | If a frontswap dup-store failed, it should invalidate the expired page in the backend, or it could trigger some data corruption issue. Such as: 1. use zswap as the frontswap backend with writeback feature 2. store a swap page(version_1) to entry A, success 3. dup-store a newer page(version_2) to the same entry A, fail 4. use __swap_writepage() write version_2 page to swapfile, success 5. zswap do shrink, writeback version_1 page to swapfile 6. version_2 page is overwrited by version_1, data corrupt. This patch fixes this issue by invalidating expired data immediately when meet a dup-store failure. Signed-off-by: Weijie Yang <weijie.yang@samsung.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Seth Jennings <sjennings@variantweb.net> Cc: Dan Streetman <ddstreet@ieee.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Bob Liu <bob.liu@oracle.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* swap: change swap_list_head to plist, add swap_avail_headDan Streetman2014-06-051-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Originally get_swap_page() started iterating through the singly-linked list of swap_info_structs using swap_list.next or highest_priority_index, which both were intended to point to the highest priority active swap target that was not full. The first patch in this series changed the singly-linked list to a doubly-linked list, and removed the logic to start at the highest priority non-full entry; it starts scanning at the highest priority entry each time, even if the entry is full. Replace the manually ordered swap_list_head with a plist, swap_active_head. Add a new plist, swap_avail_head. The original swap_active_head plist contains all active swap_info_structs, as before, while the new swap_avail_head plist contains only swap_info_structs that are active and available, i.e. not full. Add a new spinlock, swap_avail_lock, to protect the swap_avail_head list. Mel Gorman suggested using plists since they internally handle ordering the list entries based on priority, which is exactly what swap was doing manually. All the ordering code is now removed, and swap_info_struct entries and simply added to their corresponding plist and automatically ordered correctly. Using a new plist for available swap_info_structs simplifies and optimizes get_swap_page(), which no longer has to iterate over full swap_info_structs. Using a new spinlock for swap_avail_head plist allows each swap_info_struct to add or remove themselves from the plist when they become full or not-full; previously they could not do so because the swap_info_struct->lock is held when they change from full<->not-full, and the swap_lock protecting the main swap_active_head must be ordered before any swap_info_struct->lock. Signed-off-by: Dan Streetman <ddstreet@ieee.org> Acked-by: Mel Gorman <mgorman@suse.de> Cc: Shaohua Li <shli@fusionio.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Hugh Dickins <hughd@google.com> Cc: Dan Streetman <ddstreet@ieee.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com> Cc: Weijie Yang <weijieut@gmail.com> Cc: Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Bob Liu <bob.liu@oracle.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* swap: change swap_info singly-linked list to list_headDan Streetman2014-06-051-9/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The logic controlling the singly-linked list of swap_info_struct entries for all active, i.e. swapon'ed, swap targets is rather complex, because: - it stores the entries in priority order - there is a pointer to the highest priority entry - there is a pointer to the highest priority not-full entry - there is a highest_priority_index variable set outside the swap_lock - swap entries of equal priority should be used equally this complexity leads to bugs such as: https://lkml.org/lkml/2014/2/13/181 where different priority swap targets are incorrectly used equally. That bug probably could be solved with the existing singly-linked lists, but I think it would only add more complexity to the already difficult to understand get_swap_page() swap_list iteration logic. The first patch changes from a singly-linked list to a doubly-linked list using list_heads; the highest_priority_index and related code are removed and get_swap_page() starts each iteration at the highest priority swap_info entry, even if it's full. While this does introduce unnecessary list iteration (i.e. Schlemiel the painter's algorithm) in the case where one or more of the highest priority entries are full, the iteration and manipulation code is much simpler and behaves correctly re: the above bug; and the fourth patch removes the unnecessary iteration. The second patch adds some minor plist helper functions; nothing new really, just functions to match existing regular list functions. These are used by the next two patches. The third patch adds plist_requeue(), which is used by get_swap_page() in the next patch - it performs the requeueing of same-priority entries (which moves the entry to the end of its priority in the plist), so that all equal-priority swap_info_structs get used equally. The fourth patch converts the main list into a plist, and adds a new plist that contains only swap_info entries that are both active and not full. As Mel suggested using plists allows removing all the ordering code from swap - plists handle ordering automatically. The list naming is also clarified now that there are two lists, with the original list changed from swap_list_head to swap_active_head and the new list named swap_avail_head. A new spinlock is also added for the new list, so swap_info entries can be added or removed from the new list immediately as they become full or not full. This patch (of 4): Replace the singly-linked list tracking active, i.e. swapon'ed, swap_info_struct entries with a doubly-linked list using struct list_heads. Simplify the logic iterating and manipulating the list of entries, especially get_swap_page(), by using standard list_head functions, and removing the highest priority iteration logic. The change fixes the bug: https://lkml.org/lkml/2014/2/13/181 in which different priority swap entries after the highest priority entry are incorrectly used equally in pairs. The swap behavior is now as advertised, i.e. different priority swap entries are used in order, and equal priority swap targets are used concurrently. Signed-off-by: Dan Streetman <ddstreet@ieee.org> Acked-by: Mel Gorman <mgorman@suse.de> Cc: Shaohua Li <shli@fusionio.com> Cc: Hugh Dickins <hughd@google.com> Cc: Dan Streetman <ddstreet@ieee.org> Cc: Michal Hocko <mhocko@suse.cz> Cc: Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com> Cc: Weijie Yang <weijieut@gmail.com> Cc: Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Bob Liu <bob.liu@oracle.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* frontswap: fix incorrect zeroing and allocation size for frontswap_mapAkinobu Mita2013-06-131-1/+1
| | | | | | | | | | | | | | | | | | | | | | The bitmap accessed by bitops must have enough size to hold the required numbers of bits rounded up to a multiple of BITS_PER_LONG. And the bitmap must not be zeroed by memset() if the number of bits cleared is not a multiple of BITS_PER_LONG. This fixes incorrect zeroing and allocation size for frontswap_map. The incorrect zeroing part doesn't cause any problem because frontswap_map is freed just after zeroing. But the wrongly calculated allocation size may cause the problem. For 32bit systems, the allocation size of frontswap_map is about twice as large as required size. For 64bit systems, the allocation size is smaller than requeired if the number of bits is not a multiple of BITS_PER_LONG. Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* frontswap: get rid of swap_lock dependencyMinchan Kim2013-05-011-8/+23
| | | | | | | | | | | | | | | | | | | | | | | | | | 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@oracle.com> Signed-off-by: Minchan Kim <minchan@kernel.org> [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@linux.vnet.ibm.com>] Signed-off-by: Konrad Rzeszutek Wilk <konrad@darnok.org> Signed-off-by: Bob Liu <lliubbo@gmail.com> Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com> Cc: Andor Daam <andor.daam@googlemail.com> Cc: Florian Schmaus <fschmaus@gmail.com> Cc: Stefan Hengelein <ilendir@googlemail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: frontswap: cleanup codeBob Liu2013-05-011-27/+30
| | | | | | | | | | | | | | | | | | | | After allowing tmem backends to build/run as modules, frontswap_enabled always true if defined CONFIG_FRONTSWAP. But frontswap_test() depends on whether backend is registered, mv it into frontswap.c using fronstswap_ops to make the decision. frontswap_set/clear are not used outside frontswap, so don't export them. Signed-off-by: Bob Liu <lliubbo@gmail.com> Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com> Cc: Andor Daam <andor.daam@googlemail.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Florian Schmaus <fschmaus@gmail.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Stefan Hengelein <ilendir@googlemail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* frontswap: make frontswap_init use a pointer for the opsKonrad Rzeszutek Wilk2013-05-011-20/+18
| | | | | | | | | | | | | | | | | This simplifies the code in the frontswap - we can get rid of the 'backend_registered' test and instead check against frontswap_ops. [v1: Rebase on top of 703ba7fe5e0 (ramster->zcache move] Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: Bob Liu <lliubbo@gmail.com> Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com> Cc: Andor Daam <andor.daam@googlemail.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Florian Schmaus <fschmaus@gmail.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Stefan Hengelein <ilendir@googlemail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: frontswap: lazy initialization to allow tmem backends to build/run as ↵Dan Magenheimer2013-05-011-10/+84
| | | | | | | | | | | | | | | | | | | | | | | | | | | | modules With the goal of allowing tmem backends (zcache, ramster, Xen tmem) to be built/loaded as modules rather than built-in and enabled by a boot parameter, this patch provides "lazy initialization", allowing backends to register to frontswap even after swapon was run. Before a backend registers all calls to init are recorded and the creation of tmem_pools delayed until a backend registers or until a frontswap store is attempted. Signed-off-by: Stefan Hengelein <ilendir@googlemail.com> Signed-off-by: Florian Schmaus <fschmaus@gmail.com> Signed-off-by: Andor Daam <andor.daam@googlemail.com> Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com> [v1: Fixes per Seth Jennings suggestions] [v2: Removed FRONTSWAP_HAS_.. ] [v3: Fix up per Bob Liu <lliubbo@gmail.com> recommendations] [v4: Fix up per Andrew's comments] Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: Bob Liu <lliubbo@gmail.com> Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com> Cc: Dan Magenheimer <dan.magenheimer@oracle.com> Cc: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* frontswap: support exclusive gets if tmem backend is capableDan Magenheimer2012-09-211-1/+22
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Tmem, as originally specified, assumes that "get" operations performed on persistent pools never flush the page of data out of tmem on a successful get, waiting instead for a flush operation. This is intended to mimic the model of a swap disk, where a disk read is non-destructive. Unlike a disk, however, freeing up the RAM can be valuable. Over the years that frontswap was in the review process, several reviewers (and notably Hugh Dickins in 2010) pointed out that this would result, at least temporarily, in two copies of the data in RAM: one (compressed for zcache) copy in tmem, and one copy in the swap cache. We wondered if this could be done differently, at least optionally. This patch allows tmem backends to instruct the frontswap code that this backend performs exclusive gets. Zcache2 already contains hooks to support this feature. Other backends are completely unaffected unless/until they are updated to support this feature. While it is not clear that exclusive gets are a performance win on all workloads at all times, this small patch allows for experimentation by backends. P.S. Let's not quibble about the naming of "get" vs "read" vs "load" etc. The naming is currently horribly inconsistent between cleancache and frontswap and existing tmem backends, so will need to be straightened out as a separate patch. "Get" is used by the tmem architecture spec, existing backends, and all documentation and presentation material so I am using it in this patch. Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* mm: frontswap: fix a wrong if condition in frontswap_shrinkZhenzhong Duan2012-09-211-2/+7
| | | | | | | | | | | | pages_to_unuse is set to 0 to unuse all frontswap pages But that doesn't happen since a wrong condition in frontswap_shrink cancel it. -v2: Add comment to explain return value of __frontswap_shrink, as suggested by Dan Carpenter, thanks Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* mm/frontswap: fix uninit'ed variable warningSeth Jennings2012-08-131-1/+1
| | | | | | | | | | Fixes uninitialized variable warning on 'type' in frontswap_shrink(). type is set before use by __frontswap_unuse_pages() called by __frontswap_shrink() called by frontswap_shrink() before use by try_to_unuse(). Signed-off-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* mm/frontswap: cleanup doc and comment errorWanpeng Li2012-07-231-1/+1
| | | | | Signed-off-by: Wanpeng Li <liwp.linux@gmail.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* mm: frontswap: remove unneeded headersSasha Levin2012-07-231-4/+0
| | | | | | Signed-off-by: Sasha Levin <levinsasha928@gmail.com> [v1: Rebased with tracing removed] Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* mm: frontswap: split out function to clear a page outSasha Levin2012-07-201-6/+9
| | | | | Signed-off-by: Sasha Levin <levinsasha928@gmail.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* mm: frontswap: remove unnecessary check during initializationSasha Levin2012-06-111-2/+1
| | | | | | | | | | | | The check whether frontswap is enabled or not is done in the API functions in the frontswap header, before they are passed to the internal double-underscored frontswap functions. Remove the check from __frontswap_init for consistency. Reviewed-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Sasha Levin <levinsasha928@gmail.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* mm: frontswap: make all branches of if statement in put page consistentSasha Levin2012-06-111-5/+5
| | | | | | | | | Currently it has a complex structure where different things are compared at each branch. Simplify that and make both branches look similar. Reviewed-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Sasha Levin <levinsasha928@gmail.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* mm: frontswap: split frontswap_shrink further to simplify lockingSasha Levin2012-06-111-15/+21
| | | | | | | | | | Split frontswap_shrink to simplify the locking in the original code. Also, assert that the function that was split still runs under the swap spinlock. Signed-off-by: Sasha Levin <levinsasha928@gmail.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* mm: frontswap: split out __frontswap_unuse_pagesSasha Levin2012-06-111-20/+39
| | | | | | | | | | | | An attempt at making frontswap_shrink shorter and more readable. This patch splits out walking through the swap list to find an entry with enough pages to unuse. Also, assert that the internal __frontswap_unuse_pages is called under swap lock, since that part of code was previously directly happen inside the lock. Signed-off-by: Sasha Levin <levinsasha928@gmail.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* mm: frontswap: split out __frontswap_curr_pagesSasha Levin2012-06-111-11/+17
| | | | | | | | | | Code was duplicated in two functions, clean it up. Also, assert that the deduplicated code runs under the swap spinlock. Reviewed-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Sasha Levin <levinsasha928@gmail.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* mm: frontswap: trivial coding convention issuesSasha Levin2012-06-111-3/+4
| | | | | | Reviewed-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Sasha Levin <levinsasha928@gmail.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* mm: frontswap: remove casting from function calls through ops structureSasha Levin2012-06-111-5/+5
| | | | | | | | Removes unneeded casts. Reviewed-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Sasha Levin <levinsasha928@gmail.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* frontswap: s/put_page/store/g s/get_page/loadKonrad Rzeszutek Wilk2012-05-151-28/+28
| | | | | | | Sounds so much more natural. Suggested-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
* mm: frontswap: core frontswap functionalityDan Magenheimer2012-05-151-0/+314
This patch, 3of4, provides the core frontswap code that interfaces between the hooks in the swap subsystem and a frontswap backend via frontswap_ops. --- New file added: mm/frontswap.c [v14: add support for writethrough, per suggestion by aarcange@redhat.com] [v11: sjenning@linux.vnet.ibm.com: s/puts/failed_puts/] [v10: sjenning@linux.vnet.ibm.com: fix debugfs calls on 32-bit] [v9: akpm@linux-foundation.org: change "flush" to "invalidate", part 1] [v9: akpm@linux-foundation.org: mark some statics __read_mostly] [v9: akpm@linux-foundation.org: add clarifying comments] [v9: akpm@linux-foundation.org: no need to loop repeating try_to_unuse] [v9: error27@gmail.com: remove superfluous check for NULL] [v8: rebase to 3.0-rc4] [v8: kamezawa.hiroyu@jp.fujitsu.com: add comment to clarify find_next_to_unuse] [v7: rebase to 3.0-rc3] [v7: JBeulich@novell.com: use new static inlines, no-ops if not config'd] [v6: rebase to 3.1-rc1] [v6: lliubbo@gmail.com: use vzalloc] [v6: lliubbo@gmail.com: fix null pointer deref if vzalloc fails] [v6: konrad.wilk@oracl.com: various checks and code clarifications/comments] [v4: rebase to 2.6.39] Signed-off-by: Dan Magenheimer <dan.magenheimer@oracle.com> Acked-by: Jan Beulich <JBeulich@novell.com> Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Nitin Gupta <ngupta@vflare.org> Cc: Matthew Wilcox <matthew@wil.cx> Cc: Chris Mason <chris.mason@oracle.com> Cc: Rik Riel <riel@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org> [v12: Squashed s/flush/invalidate/ in] [v15: A bit of cleanup and seperate DEBUGFS] Signed-off-by: Konrad Wilk <konrad.wilk@oracle.com>
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