* Re: [RFC 1/7] mm: introduce MADV_COOL [not found] <20190528121523.8764-1-hdanton@sina.com> @ 2019-05-28 12:39 ` Minchan Kim 0 siblings, 0 replies; 13+ messages in thread From: Minchan Kim @ 2019-05-28 12:39 UTC (permalink / raw) To: Hillf Danton Cc: Andrew Morton, LKML, linux-mm, Michal Hocko, Johannes Weiner, Tim Murray, Joel Fernandes, Suren Baghdasaryan, Daniel Colascione, Shakeel Butt, Sonny Rao, Brian Geffon On Tue, May 28, 2019 at 08:15:23PM +0800, Hillf Danton wrote: < snip > > > > > + > > > > + get_page(page); > > > > + spin_unlock(ptl); > > > > + lock_page(page); > > > > + err = split_huge_page(page); > > > > + unlock_page(page); > > > > + put_page(page); > > > > + if (!err) > > > > + goto regular_page; > > > > + return 0; > > > > + } > > > > + > > > > + pmdp_test_and_clear_young(vma, addr, pmd); > > > > + deactivate_page(page); > > > > +huge_unlock: > > > > + spin_unlock(ptl); > > > > + return 0; > > > > + } > > > > + > > > > + if (pmd_trans_unstable(pmd)) > > > > + return 0; > > > > + > > > > +regular_page: > > > > > > Take a look at pending signal? > > > > Do you have any reason to see pending signal here? I want to know what's > > your requirement so that what's the better place to handle it. > > > We could bail out without work done IMO if there is a fatal siganl pending. > And we can do that, if it makes sense to you, before the hard work. Make sense, especically, swapping out. I will add it in next revision. > > > > > > > > + orig_pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); > > > > + for (pte = orig_pte; addr < end; pte++, addr += PAGE_SIZE) { > > > > > > s/end/next/ ? > > > > Why do you think it should be next? > > > Simply based on the following line, and afraid that next != end > > > > + next = pmd_addr_end(addr, end); pmd_addr_end will return smaller address so end is more proper. > > > > > + ptent = *pte; > > > > + > > > > + if (pte_none(ptent)) > > > > + continue; > > > > + > > > > + if (!pte_present(ptent)) > > > > + continue; > > > > + > > > > + page = vm_normal_page(vma, addr, ptent); > > > > + if (!page) > > > > + continue; > > > > + > > > > + if (page_mapcount(page) > 1) > > > > + continue; > > > > + > > > > + ptep_test_and_clear_young(vma, addr, pte); > > > > + deactivate_page(page); > > > > + } > > > > + > > > > + pte_unmap_unlock(orig_pte, ptl); > > > > + cond_resched(); > > > > + > > > > + return 0; > > > > +} > > > > + > > > > +static long madvise_cool(struct vm_area_struct *vma, > > > > + unsigned long start_addr, unsigned long end_addr) > > > > +{ > > > > + struct mm_struct *mm = vma->vm_mm; > > > > + struct mmu_gather tlb; > > > > + > > > > + if (vma->vm_flags & (VM_LOCKED|VM_HUGETLB|VM_PFNMAP)) > > > > + return -EINVAL; > > > > > > No service in case of VM_IO? > > > > I don't know VM_IO would have regular LRU pages but just follow normal > > convention for DONTNEED and FREE. > > Do you have anything in your mind? > > > I want to skip a mapping set up for DMA. What you meant is those pages in VM_IO vma are not in LRU list? Or pages in the vma are always pinned so no worth to deactivate or reclaim? ^ permalink raw reply [flat|nested] 13+ messages in thread
[parent not found: <20190529024033.13500-1-hdanton@sina.com>]
* Re: [RFC 1/7] mm: introduce MADV_COOL [not found] <20190529024033.13500-1-hdanton@sina.com> @ 2019-05-29 5:05 ` Michal Hocko 0 siblings, 0 replies; 13+ messages in thread From: Michal Hocko @ 2019-05-29 5:05 UTC (permalink / raw) To: Hillf Danton Cc: Minchan Kim, Andrew Morton, LKML, linux-mm, Johannes Weiner, Tim Murray, Joel Fernandes, Suren Baghdasaryan, Daniel Colascione, Shakeel Butt, Sonny Rao, Brian Geffon On Wed 29-05-19 10:40:33, Hillf Danton wrote: > > On Wed, 29 May 2019 00:11:15 +0800 Michal Hocko wrote: > > On Tue 28-05-19 23:38:11, Hillf Danton wrote: > > > > > > In short, I prefer to skip IO mapping since any kind of address range > > > can be expected from userspace, and it may probably cover an IO mapping. > > > And things can get out of control, if we reclaim some IO pages while > > > underlying device is trying to fill data into any of them, for instance. > > > > What do you mean by IO pages why what is the actual problem? > > > Io pages are the backing-store pages of a mapping whose vm_flags has > VM_IO set, and the comment in mm/memory.c says: > /* > * Physically remapped pages are special. Tell the > * rest of the world about it: > * VM_IO tells people not to look at these pages > * (accesses can have side effects). > OK, thanks for the clarification of the first part of the question. Now to the second and the more important one. What is the actual concern? AFAIK those pages shouldn't be on LRU list. If they are then they should be safe to get reclaimed otherwise we would have a problem when reclaiming them on the normal memory pressure. Why is this madvise any different? -- Michal Hocko SUSE Labs ^ permalink raw reply [flat|nested] 13+ messages in thread
[parent not found: <20190528153811.7684-1-hdanton@sina.com>]
* Re: [RFC 1/7] mm: introduce MADV_COOL [not found] <20190528153811.7684-1-hdanton@sina.com> @ 2019-05-28 16:11 ` Michal Hocko 0 siblings, 0 replies; 13+ messages in thread From: Michal Hocko @ 2019-05-28 16:11 UTC (permalink / raw) To: Hillf Danton Cc: Minchan Kim, Andrew Morton, LKML, linux-mm, Johannes Weiner, Tim Murray, Joel Fernandes, Suren Baghdasaryan, Daniel Colascione, Shakeel Butt, Sonny Rao, Brian Geffon On Tue 28-05-19 23:38:11, Hillf Danton wrote: > > On Tue, 28 May 2019 20:39:36 +0800 Minchan Kim wrote: > > On Tue, May 28, 2019 at 08:15:23PM +0800, Hillf Danton wrote: > > < snip > > > > > > > + orig_pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); > > > > > > + for (pte = orig_pte; addr < end; pte++, addr += PAGE_SIZE) { > > > > > > > > > > s/end/next/ ? > > > > > > > > Why do you think it should be next? > > > > > > > Simply based on the following line, and afraid that next != end > > > > > > + next = pmd_addr_end(addr, end); > > > > pmd_addr_end will return smaller address so end is more proper. > > > Fair. > > > > > > > +static long madvise_cool(struct vm_area_struct *vma, > > > > > > + unsigned long start_addr, unsigned long end_addr) > > > > > > +{ > > > > > > + struct mm_struct *mm = vma->vm_mm; > > > > > > + struct mmu_gather tlb; > > > > > > + > > > > > > + if (vma->vm_flags & (VM_LOCKED|VM_HUGETLB|VM_PFNMAP)) > > > > > > + return -EINVAL; > > > > > > > > > > No service in case of VM_IO? > > > > > > > > I don't know VM_IO would have regular LRU pages but just follow normal > > > > convention for DONTNEED and FREE. > > > > Do you have anything in your mind? > > > > > > > I want to skip a mapping set up for DMA. > > > > What you meant is those pages in VM_IO vma are not in LRU list? > > What I concern is the case that there are IO pages on lru list. > > Or > > pages in the vma are always pinned so no worth to deactivate or reclaim? > > > I will not be nervous or paranoid if they are pinned. > > In short, I prefer to skip IO mapping since any kind of address range > can be expected from userspace, and it may probably cover an IO mapping. > And things can get out of control, if we reclaim some IO pages while > underlying device is trying to fill data into any of them, for instance. What do you mean by IO pages why what is the actual problem? -- Michal Hocko SUSE Labs ^ permalink raw reply [flat|nested] 13+ messages in thread
* [RFC 0/7] introduce memory hinting API for external process @ 2019-05-20 3:52 Minchan Kim 2019-05-20 3:52 ` [RFC 1/7] mm: introduce MADV_COOL Minchan Kim 0 siblings, 1 reply; 13+ messages in thread From: Minchan Kim @ 2019-05-20 3:52 UTC (permalink / raw) To: Andrew Morton Cc: LKML, linux-mm, Michal Hocko, Johannes Weiner, Tim Murray, Joel Fernandes, Suren Baghdasaryan, Daniel Colascione, Shakeel Butt, Sonny Rao, Brian Geffon, Minchan Kim - Background The Android terminology used for forking a new process and starting an app from scratch is a cold start, while resuming an existing app is a hot start. While we continually try to improve the performance of cold starts, hot starts will always be significantly less power hungry as well as faster so we are trying to make hot start more likely than cold start. To increase hot start, Android userspace manages the order that apps should be killed in a process called ActivityManagerService. ActivityManagerService tracks every Android app or service that the user could be interacting with at any time and translates that into a ranked list for lmkd(low memory killer daemon). They are likely to be killed by lmkd if the system has to reclaim memory. In that sense they are similar to entries in any other cache. Those apps are kept alive for opportunistic performance improvements but those performance improvements will vary based on the memory requirements of individual workloads. - Problem Naturally, cached apps were dominant consumers of memory on the system. However, they were not significant consumers of swap even though they are good candidate for swap. Under investigation, swapping out only begins once the low zone watermark is hit and kswapd wakes up, but the overall allocation rate in the system might trip lmkd thresholds and cause a cached process to be killed(we measured performance swapping out vs. zapping the memory by killing a process. Unsurprisingly, zapping is 10x times faster even though we use zram which is much faster than real storage) so kill from lmkd will often satisfy the high zone watermark, resulting in very few pages actually being moved to swap. - Approach The approach we chose was to use a new interface to allow userspace to proactively reclaim entire processes by leveraging platform information. This allowed us to bypass the inaccuracy of the kernel’s LRUs for pages that are known to be cold from userspace and to avoid races with lmkd by reclaiming apps as soon as they entered the cached state. Additionally, it could provide many chances for platform to use much information to optimize memory efficiency. IMHO we should spell it out that this patchset complements MADV_WONTNEED and MADV_FREE by adding non-destructive ways to gain some free memory space. MADV_COLD is similar to MADV_WONTNEED in a way that it hints the kernel that memory region is not currently needed and should be reclaimed immediately; MADV_COOL is similar to MADV_FREE in a way that it hints the kernel that memory region is not currently needed and should be reclaimed when memory pressure rises. To achieve the goal, the patchset introduce two new options for madvise. One is MADV_COOL which will deactive activated pages and the other is MADV_COLD which will reclaim private pages instantly. These new options complement MADV_DONTNEED and MADV_FREE by adding non-destructive ways to gain some free memory space. MADV_COLD is similar to MADV_DONTNEED in a way that it hints the kernel that memory region is not currently needed and should be reclaimed immediately; MADV_COOL is similar to MADV_FREE in a way that it hints the kernel that memory region is not currently needed and should be reclaimed when memory pressure rises. This approach is similar in spirit to madvise(MADV_WONTNEED), but the information required to make the reclaim decision is not known to the app. Instead, it is known to a centralized userspace daemon, and that daemon must be able to initiate reclaim on its own without any app involvement. To solve the concern, this patch introduces new syscall - struct pr_madvise_param { int size; const struct iovec *vec; } int process_madvise(int pidfd, ssize_t nr_elem, int *behavior, struct pr_madvise_param *restuls, struct pr_madvise_param *ranges, unsigned long flags); The syscall get pidfd to give hints to external process and provides pair of result/ranges vector arguments so that it could give several hints to each address range all at once. I guess others have different ideas about the naming of syscall and options so feel free to suggest better naming. - Experiment We did bunch of testing with several hundreds of real users, not artificial benchmark on android. We saw about 17% cold start decreasement without any significant battery/app startup latency issues. And with artificial benchmark which launches and switching apps, we saw average 7% app launching improvement, 18% less lmkd kill and good stat from vmstat. A is vanilla and B is process_madvise. A B delta ratio(%) allocstall_dma 0 0 0 0.00 allocstall_movable 1464 457 -1007 -69.00 allocstall_normal 263210 190763 -72447 -28.00 allocstall_total 264674 191220 -73454 -28.00 compact_daemon_wake 26912 25294 -1618 -7.00 compact_fail 17885 14151 -3734 -21.00 compact_free_scanned 4204766409 3835994922 -368771487 -9.00 compact_isolated 3446484 2967618 -478866 -14.00 compact_migrate_scanned 1621336411 1324695710 -296640701 -19.00 compact_stall 19387 15343 -4044 -21.00 compact_success 1502 1192 -310 -21.00 kswapd_high_wmark_hit_quickly 234 184 -50 -22.00 kswapd_inodesteal 221635 233093 11458 5.00 kswapd_low_wmark_hit_quickly 66065 54009 -12056 -19.00 nr_dirtied 259934 296476 36542 14.00 nr_vmscan_immediate_reclaim 2587 2356 -231 -9.00 nr_vmscan_write 1274232 2661733 1387501 108.00 nr_written 1514060 2937560 1423500 94.00 pageoutrun 67561 55133 -12428 -19.00 pgactivate 2335060 1984882 -350178 -15.00 pgalloc_dma 13743011 14096463 353452 2.00 pgalloc_movable 0 0 0 0.00 pgalloc_normal 18742440 16802065 -1940375 -11.00 pgalloc_total 32485451 30898528 -1586923 -5.00 pgdeactivate 4262210 2930670 -1331540 -32.00 pgfault 30812334 31085065 272731 0.00 pgfree 33553970 31765164 -1788806 -6.00 pginodesteal 33411 15084 -18327 -55.00 pglazyfreed 0 0 0 0.00 pgmajfault 551312 1508299 956987 173.00 pgmigrate_fail 43927 29330 -14597 -34.00 pgmigrate_success 1399851 1203922 -195929 -14.00 pgpgin 24141776 19032156 -5109620 -22.00 pgpgout 959344 1103316 143972 15.00 pgpgoutclean 4639732 3765868 -873864 -19.00 pgrefill 4884560 3006938 -1877622 -39.00 pgrotated 37828 25897 -11931 -32.00 pgscan_direct 1456037 957567 -498470 -35.00 pgscan_direct_throttle 0 0 0 0.00 pgscan_kswapd 6667767 5047360 -1620407 -25.00 pgscan_total 8123804 6004927 -2118877 -27.00 pgskip_dma 0 0 0 0.00 pgskip_movable 0 0 0 0.00 pgskip_normal 14907 25382 10475 70.00 pgskip_total 14907 25382 10475 70.00 pgsteal_direct 1118986 690215 -428771 -39.00 pgsteal_kswapd 4750223 3657107 -1093116 -24.00 pgsteal_total 5869209 4347322 -1521887 -26.00 pswpin 417613 1392647 975034 233.00 pswpout 1274224 2661731 1387507 108.00 slabs_scanned 13686905 10807200 -2879705 -22.00 workingset_activate 668966 569444 -99522 -15.00 workingset_nodereclaim 38957 32621 -6336 -17.00 workingset_refault 2816795 2179782 -637013 -23.00 workingset_restore 294320 168601 -125719 -43.00 pgmajfault is increased by 173% because swapin is increased by 200% by process_madvise hint. However, swap read based on zram is much cheaper than file IO in performance point of view and app hot start by swapin is also cheaper than cold start from the beginning of app which needs many IO from storage and initialization steps. This patchset is against on next-20190517. Minchan Kim (7): mm: introduce MADV_COOL mm: change PAGEREF_RECLAIM_CLEAN with PAGE_REFRECLAIM mm: introduce MADV_COLD mm: factor out madvise's core functionality mm: introduce external memory hinting API mm: extend process_madvise syscall to support vector arrary mm: madvise support MADV_ANONYMOUS_FILTER and MADV_FILE_FILTER arch/x86/entry/syscalls/syscall_32.tbl | 1 + arch/x86/entry/syscalls/syscall_64.tbl | 1 + include/linux/page-flags.h | 1 + include/linux/page_idle.h | 15 + include/linux/proc_fs.h | 1 + include/linux/swap.h | 2 + include/linux/syscalls.h | 2 + include/uapi/asm-generic/mman-common.h | 12 + include/uapi/asm-generic/unistd.h | 2 + kernel/signal.c | 2 +- kernel/sys_ni.c | 1 + mm/madvise.c | 600 +++++++++++++++++++++---- mm/swap.c | 43 ++ mm/vmscan.c | 80 +++- 14 files changed, 680 insertions(+), 83 deletions(-) -- 2.21.0.1020.gf2820cf01a-goog ^ permalink raw reply [flat|nested] 13+ messages in thread
* [RFC 1/7] mm: introduce MADV_COOL 2019-05-20 3:52 [RFC 0/7] introduce memory hinting API for external process Minchan Kim @ 2019-05-20 3:52 ` Minchan Kim 2019-05-20 8:16 ` Michal Hocko 2019-05-28 10:58 ` Minchan Kim 0 siblings, 2 replies; 13+ messages in thread From: Minchan Kim @ 2019-05-20 3:52 UTC (permalink / raw) To: Andrew Morton Cc: LKML, linux-mm, Michal Hocko, Johannes Weiner, Tim Murray, Joel Fernandes, Suren Baghdasaryan, Daniel Colascione, Shakeel Butt, Sonny Rao, Brian Geffon, Minchan Kim When a process expects no accesses to a certain memory range it could hint kernel that the pages can be reclaimed when memory pressure happens but data should be preserved for future use. This could reduce workingset eviction so it ends up increasing performance. This patch introduces the new MADV_COOL hint to madvise(2) syscall. MADV_COOL can be used by a process to mark a memory range as not expected to be used in the near future. The hint can help kernel in deciding which pages to evict early during memory pressure. Internally, it works via deactivating memory from active list to inactive's head so when the memory pressure happens, they will be reclaimed earlier than other active pages unless there is no access until the time. * v1r2 * use clear_page_young in deactivate_page - joelaf * v1r1 * Revise the description - surenb * Renaming from MADV_WARM to MADV_COOL - surenb Signed-off-by: Minchan Kim <minchan@kernel.org> --- include/linux/page-flags.h | 1 + include/linux/page_idle.h | 15 ++++ include/linux/swap.h | 1 + include/uapi/asm-generic/mman-common.h | 1 + mm/madvise.c | 112 +++++++++++++++++++++++++ mm/swap.c | 43 ++++++++++ 6 files changed, 173 insertions(+) diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index 9f8712a4b1a5..58b06654c8dd 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -424,6 +424,7 @@ static inline bool set_hwpoison_free_buddy_page(struct page *page) TESTPAGEFLAG(Young, young, PF_ANY) SETPAGEFLAG(Young, young, PF_ANY) TESTCLEARFLAG(Young, young, PF_ANY) +CLEARPAGEFLAG(Young, young, PF_ANY) PAGEFLAG(Idle, idle, PF_ANY) #endif diff --git a/include/linux/page_idle.h b/include/linux/page_idle.h index 1e894d34bdce..f3f43b317150 100644 --- a/include/linux/page_idle.h +++ b/include/linux/page_idle.h @@ -19,6 +19,11 @@ static inline void set_page_young(struct page *page) SetPageYoung(page); } +static inline void clear_page_young(struct page *page) +{ + ClearPageYoung(page); +} + static inline bool test_and_clear_page_young(struct page *page) { return TestClearPageYoung(page); @@ -65,6 +70,16 @@ static inline void set_page_young(struct page *page) set_bit(PAGE_EXT_YOUNG, &page_ext->flags); } +static void clear_page_young(struct page *page) +{ + struct page_ext *page_ext = lookup_page_ext(page); + + if (unlikely(!page_ext)) + return; + + clear_bit(PAGE_EXT_YOUNG, &page_ext->flags); +} + static inline bool test_and_clear_page_young(struct page *page) { struct page_ext *page_ext = lookup_page_ext(page); diff --git a/include/linux/swap.h b/include/linux/swap.h index 4bfb5c4ac108..64795abea003 100644 --- a/include/linux/swap.h +++ b/include/linux/swap.h @@ -340,6 +340,7 @@ extern void lru_add_drain_cpu(int cpu); extern void lru_add_drain_all(void); extern void rotate_reclaimable_page(struct page *page); extern void deactivate_file_page(struct page *page); +extern void deactivate_page(struct page *page); extern void mark_page_lazyfree(struct page *page); extern void swap_setup(void); diff --git a/include/uapi/asm-generic/mman-common.h b/include/uapi/asm-generic/mman-common.h index abd238d0f7a4..f7a4a5d4b642 100644 --- a/include/uapi/asm-generic/mman-common.h +++ b/include/uapi/asm-generic/mman-common.h @@ -42,6 +42,7 @@ #define MADV_SEQUENTIAL 2 /* expect sequential page references */ #define MADV_WILLNEED 3 /* will need these pages */ #define MADV_DONTNEED 4 /* don't need these pages */ +#define MADV_COOL 5 /* deactivatie these pages */ /* common parameters: try to keep these consistent across architectures */ #define MADV_FREE 8 /* free pages only if memory pressure */ diff --git a/mm/madvise.c b/mm/madvise.c index 628022e674a7..c05817fb570d 100644 --- a/mm/madvise.c +++ b/mm/madvise.c @@ -8,6 +8,7 @@ #include <linux/mman.h> #include <linux/pagemap.h> +#include <linux/page_idle.h> #include <linux/syscalls.h> #include <linux/mempolicy.h> #include <linux/page-isolation.h> @@ -40,6 +41,7 @@ static int madvise_need_mmap_write(int behavior) case MADV_REMOVE: case MADV_WILLNEED: case MADV_DONTNEED: + case MADV_COOL: case MADV_FREE: return 0; default: @@ -307,6 +309,113 @@ static long madvise_willneed(struct vm_area_struct *vma, return 0; } +static int madvise_cool_pte_range(pmd_t *pmd, unsigned long addr, + unsigned long end, struct mm_walk *walk) +{ + pte_t *orig_pte, *pte, ptent; + spinlock_t *ptl; + struct page *page; + struct vm_area_struct *vma = walk->vma; + unsigned long next; + + next = pmd_addr_end(addr, end); + if (pmd_trans_huge(*pmd)) { + spinlock_t *ptl; + + ptl = pmd_trans_huge_lock(pmd, vma); + if (!ptl) + return 0; + + if (is_huge_zero_pmd(*pmd)) + goto huge_unlock; + + page = pmd_page(*pmd); + if (page_mapcount(page) > 1) + goto huge_unlock; + + if (next - addr != HPAGE_PMD_SIZE) { + int err; + + get_page(page); + spin_unlock(ptl); + lock_page(page); + err = split_huge_page(page); + unlock_page(page); + put_page(page); + if (!err) + goto regular_page; + return 0; + } + + pmdp_test_and_clear_young(vma, addr, pmd); + deactivate_page(page); +huge_unlock: + spin_unlock(ptl); + return 0; + } + + if (pmd_trans_unstable(pmd)) + return 0; + +regular_page: + orig_pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); + for (pte = orig_pte; addr < end; pte++, addr += PAGE_SIZE) { + ptent = *pte; + + if (pte_none(ptent)) + continue; + + if (!pte_present(ptent)) + continue; + + page = vm_normal_page(vma, addr, ptent); + if (!page) + continue; + + if (page_mapcount(page) > 1) + continue; + + ptep_test_and_clear_young(vma, addr, pte); + deactivate_page(page); + } + + pte_unmap_unlock(orig_pte, ptl); + cond_resched(); + + return 0; +} + +static void madvise_cool_page_range(struct mmu_gather *tlb, + struct vm_area_struct *vma, + unsigned long addr, unsigned long end) +{ + struct mm_walk cool_walk = { + .pmd_entry = madvise_cool_pte_range, + .mm = vma->vm_mm, + }; + + tlb_start_vma(tlb, vma); + walk_page_range(addr, end, &cool_walk); + tlb_end_vma(tlb, vma); +} + +static long madvise_cool(struct vm_area_struct *vma, + unsigned long start_addr, unsigned long end_addr) +{ + struct mm_struct *mm = vma->vm_mm; + struct mmu_gather tlb; + + if (vma->vm_flags & (VM_LOCKED|VM_HUGETLB|VM_PFNMAP)) + return -EINVAL; + + lru_add_drain(); + tlb_gather_mmu(&tlb, mm, start_addr, end_addr); + madvise_cool_page_range(&tlb, vma, start_addr, end_addr); + tlb_finish_mmu(&tlb, start_addr, end_addr); + + return 0; +} + static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, struct mm_walk *walk) @@ -695,6 +804,8 @@ madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev, return madvise_remove(vma, prev, start, end); case MADV_WILLNEED: return madvise_willneed(vma, prev, start, end); + case MADV_COOL: + return madvise_cool(vma, start, end); case MADV_FREE: case MADV_DONTNEED: return madvise_dontneed_free(vma, prev, start, end, behavior); @@ -716,6 +827,7 @@ madvise_behavior_valid(int behavior) case MADV_WILLNEED: case MADV_DONTNEED: case MADV_FREE: + case MADV_COOL: #ifdef CONFIG_KSM case MADV_MERGEABLE: case MADV_UNMERGEABLE: diff --git a/mm/swap.c b/mm/swap.c index 3a75722e68a9..0f94c3b5397d 100644 --- a/mm/swap.c +++ b/mm/swap.c @@ -46,6 +46,7 @@ int page_cluster; static DEFINE_PER_CPU(struct pagevec, lru_add_pvec); static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs); static DEFINE_PER_CPU(struct pagevec, lru_deactivate_file_pvecs); +static DEFINE_PER_CPU(struct pagevec, lru_deactivate_pvecs); static DEFINE_PER_CPU(struct pagevec, lru_lazyfree_pvecs); #ifdef CONFIG_SMP static DEFINE_PER_CPU(struct pagevec, activate_page_pvecs); @@ -537,6 +538,23 @@ static void lru_deactivate_file_fn(struct page *page, struct lruvec *lruvec, update_page_reclaim_stat(lruvec, file, 0); } +static void lru_deactivate_fn(struct page *page, struct lruvec *lruvec, + void *arg) +{ + if (PageLRU(page) && PageActive(page) && !PageUnevictable(page)) { + int file = page_is_file_cache(page); + int lru = page_lru_base_type(page); + + del_page_from_lru_list(page, lruvec, lru + LRU_ACTIVE); + ClearPageActive(page); + ClearPageReferenced(page); + clear_page_young(page); + add_page_to_lru_list(page, lruvec, lru); + + __count_vm_events(PGDEACTIVATE, hpage_nr_pages(page)); + update_page_reclaim_stat(lruvec, file, 0); + } +} static void lru_lazyfree_fn(struct page *page, struct lruvec *lruvec, void *arg) @@ -589,6 +607,10 @@ void lru_add_drain_cpu(int cpu) if (pagevec_count(pvec)) pagevec_lru_move_fn(pvec, lru_deactivate_file_fn, NULL); + pvec = &per_cpu(lru_deactivate_pvecs, cpu); + if (pagevec_count(pvec)) + pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL); + pvec = &per_cpu(lru_lazyfree_pvecs, cpu); if (pagevec_count(pvec)) pagevec_lru_move_fn(pvec, lru_lazyfree_fn, NULL); @@ -622,6 +644,26 @@ void deactivate_file_page(struct page *page) } } +/* + * deactivate_page - deactivate a page + * @page: page to deactivate + * + * deactivate_page() moves @page to the inactive list if @page was on the active + * list and was not an unevictable page. This is done to accelerate the reclaim + * of @page. + */ +void deactivate_page(struct page *page) +{ + if (PageLRU(page) && PageActive(page) && !PageUnevictable(page)) { + struct pagevec *pvec = &get_cpu_var(lru_deactivate_pvecs); + + get_page(page); + if (!pagevec_add(pvec, page) || PageCompound(page)) + pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL); + put_cpu_var(lru_deactivate_pvecs); + } +} + /** * mark_page_lazyfree - make an anon page lazyfree * @page: page to deactivate @@ -686,6 +728,7 @@ void lru_add_drain_all(void) if (pagevec_count(&per_cpu(lru_add_pvec, cpu)) || pagevec_count(&per_cpu(lru_rotate_pvecs, cpu)) || pagevec_count(&per_cpu(lru_deactivate_file_pvecs, cpu)) || + pagevec_count(&per_cpu(lru_deactivate_pvecs, cpu)) || pagevec_count(&per_cpu(lru_lazyfree_pvecs, cpu)) || need_activate_page_drain(cpu)) { INIT_WORK(work, lru_add_drain_per_cpu); -- 2.21.0.1020.gf2820cf01a-goog ^ permalink raw reply related [flat|nested] 13+ messages in thread
* Re: [RFC 1/7] mm: introduce MADV_COOL 2019-05-20 3:52 ` [RFC 1/7] mm: introduce MADV_COOL Minchan Kim @ 2019-05-20 8:16 ` Michal Hocko 2019-05-20 8:19 ` Michal Hocko 2019-05-20 22:54 ` Minchan Kim 2019-05-28 10:58 ` Minchan Kim 1 sibling, 2 replies; 13+ messages in thread From: Michal Hocko @ 2019-05-20 8:16 UTC (permalink / raw) To: Minchan Kim Cc: Andrew Morton, LKML, linux-mm, Johannes Weiner, Tim Murray, Joel Fernandes, Suren Baghdasaryan, Daniel Colascione, Shakeel Butt, Sonny Rao, Brian Geffon, linux-api [CC linux-api] On Mon 20-05-19 12:52:48, Minchan Kim wrote: > When a process expects no accesses to a certain memory range > it could hint kernel that the pages can be reclaimed > when memory pressure happens but data should be preserved > for future use. This could reduce workingset eviction so it > ends up increasing performance. > > This patch introduces the new MADV_COOL hint to madvise(2) > syscall. MADV_COOL can be used by a process to mark a memory range > as not expected to be used in the near future. The hint can help > kernel in deciding which pages to evict early during memory > pressure. I do not want to start naming fight but MADV_COOL sounds a bit misleading. Everybody thinks his pages are cool ;). Probably MADV_COLD or MADV_DONTNEED_PRESERVE. > Internally, it works via deactivating memory from active list to > inactive's head so when the memory pressure happens, they will be > reclaimed earlier than other active pages unless there is no > access until the time. Could you elaborate about the decision to move to the head rather than tail? What should happen to inactive pages? Should we move them to the tail? Your implementation seems to ignore those completely. Why? What should happen for shared pages? In other words do we want to allow less privileged process to control evicting of shared pages with a more privileged one? E.g. think of all sorts of side channel attacks. Maybe we want to do the same thing as for mincore where write access is required. -- Michal Hocko SUSE Labs ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [RFC 1/7] mm: introduce MADV_COOL 2019-05-20 8:16 ` Michal Hocko @ 2019-05-20 8:19 ` Michal Hocko 2019-05-20 15:08 ` Suren Baghdasaryan 2019-05-20 22:55 ` Minchan Kim 2019-05-20 22:54 ` Minchan Kim 1 sibling, 2 replies; 13+ messages in thread From: Michal Hocko @ 2019-05-20 8:19 UTC (permalink / raw) To: Minchan Kim Cc: Andrew Morton, LKML, linux-mm, Johannes Weiner, Tim Murray, Joel Fernandes, Suren Baghdasaryan, Daniel Colascione, Shakeel Butt, Sonny Rao, Brian Geffon, linux-api On Mon 20-05-19 10:16:21, Michal Hocko wrote: > [CC linux-api] > > On Mon 20-05-19 12:52:48, Minchan Kim wrote: > > When a process expects no accesses to a certain memory range > > it could hint kernel that the pages can be reclaimed > > when memory pressure happens but data should be preserved > > for future use. This could reduce workingset eviction so it > > ends up increasing performance. > > > > This patch introduces the new MADV_COOL hint to madvise(2) > > syscall. MADV_COOL can be used by a process to mark a memory range > > as not expected to be used in the near future. The hint can help > > kernel in deciding which pages to evict early during memory > > pressure. > > I do not want to start naming fight but MADV_COOL sounds a bit > misleading. Everybody thinks his pages are cool ;). Probably MADV_COLD > or MADV_DONTNEED_PRESERVE. OK, I can see that you have used MADV_COLD for a different mode. So this one is effectively a non destructive MADV_FREE alternative so MADV_FREE_PRESERVE would sound like a good fit. Your MADV_COLD in other patch would then be MADV_DONTNEED_PRESERVE. Right? -- Michal Hocko SUSE Labs ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [RFC 1/7] mm: introduce MADV_COOL 2019-05-20 8:19 ` Michal Hocko @ 2019-05-20 15:08 ` Suren Baghdasaryan 2019-05-20 22:55 ` Minchan Kim 1 sibling, 0 replies; 13+ messages in thread From: Suren Baghdasaryan @ 2019-05-20 15:08 UTC (permalink / raw) To: Michal Hocko Cc: Minchan Kim, Andrew Morton, LKML, linux-mm, Johannes Weiner, Tim Murray, Joel Fernandes, Daniel Colascione, Shakeel Butt, Sonny Rao, Brian Geffon, linux-api On Mon, May 20, 2019 at 1:19 AM Michal Hocko <mhocko@kernel.org> wrote: > > On Mon 20-05-19 10:16:21, Michal Hocko wrote: > > [CC linux-api] > > > > On Mon 20-05-19 12:52:48, Minchan Kim wrote: > > > When a process expects no accesses to a certain memory range > > > it could hint kernel that the pages can be reclaimed > > > when memory pressure happens but data should be preserved > > > for future use. This could reduce workingset eviction so it > > > ends up increasing performance. > > > > > > This patch introduces the new MADV_COOL hint to madvise(2) > > > syscall. MADV_COOL can be used by a process to mark a memory range > > > as not expected to be used in the near future. The hint can help > > > kernel in deciding which pages to evict early during memory > > > pressure. > > > > I do not want to start naming fight but MADV_COOL sounds a bit > > misleading. Everybody thinks his pages are cool ;). Probably MADV_COLD > > or MADV_DONTNEED_PRESERVE. > > OK, I can see that you have used MADV_COLD for a different mode. > So this one is effectively a non destructive MADV_FREE alternative > so MADV_FREE_PRESERVE would sound like a good fit. Your MADV_COLD > in other patch would then be MADV_DONTNEED_PRESERVE. Right? > I agree that naming them this way would be more in-line with the existing API. Another good option IMO could be MADV_RECLAIM_NOW / MADV_RECLAIM_LAZY which might explain a bit better what they do but Michal's proposal is more consistent with the current API. > -- > Michal Hocko > SUSE Labs ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [RFC 1/7] mm: introduce MADV_COOL 2019-05-20 8:19 ` Michal Hocko 2019-05-20 15:08 ` Suren Baghdasaryan @ 2019-05-20 22:55 ` Minchan Kim 1 sibling, 0 replies; 13+ messages in thread From: Minchan Kim @ 2019-05-20 22:55 UTC (permalink / raw) To: Michal Hocko Cc: Andrew Morton, LKML, linux-mm, Johannes Weiner, Tim Murray, Joel Fernandes, Suren Baghdasaryan, Daniel Colascione, Shakeel Butt, Sonny Rao, Brian Geffon, linux-api On Mon, May 20, 2019 at 10:19:43AM +0200, Michal Hocko wrote: > On Mon 20-05-19 10:16:21, Michal Hocko wrote: > > [CC linux-api] > > > > On Mon 20-05-19 12:52:48, Minchan Kim wrote: > > > When a process expects no accesses to a certain memory range > > > it could hint kernel that the pages can be reclaimed > > > when memory pressure happens but data should be preserved > > > for future use. This could reduce workingset eviction so it > > > ends up increasing performance. > > > > > > This patch introduces the new MADV_COOL hint to madvise(2) > > > syscall. MADV_COOL can be used by a process to mark a memory range > > > as not expected to be used in the near future. The hint can help > > > kernel in deciding which pages to evict early during memory > > > pressure. > > > > I do not want to start naming fight but MADV_COOL sounds a bit > > misleading. Everybody thinks his pages are cool ;). Probably MADV_COLD > > or MADV_DONTNEED_PRESERVE. > > OK, I can see that you have used MADV_COLD for a different mode. > So this one is effectively a non destructive MADV_FREE alternative > so MADV_FREE_PRESERVE would sound like a good fit. Your MADV_COLD > in other patch would then be MADV_DONTNEED_PRESERVE. Right? Correct. ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [RFC 1/7] mm: introduce MADV_COOL 2019-05-20 8:16 ` Michal Hocko 2019-05-20 8:19 ` Michal Hocko @ 2019-05-20 22:54 ` Minchan Kim 2019-05-21 6:04 ` Michal Hocko 1 sibling, 1 reply; 13+ messages in thread From: Minchan Kim @ 2019-05-20 22:54 UTC (permalink / raw) To: Michal Hocko Cc: Andrew Morton, LKML, linux-mm, Johannes Weiner, Tim Murray, Joel Fernandes, Suren Baghdasaryan, Daniel Colascione, Shakeel Butt, Sonny Rao, Brian Geffon, linux-api On Mon, May 20, 2019 at 10:16:21AM +0200, Michal Hocko wrote: > [CC linux-api] Thanks, Michal. I forgot to add it. > > On Mon 20-05-19 12:52:48, Minchan Kim wrote: > > When a process expects no accesses to a certain memory range > > it could hint kernel that the pages can be reclaimed > > when memory pressure happens but data should be preserved > > for future use. This could reduce workingset eviction so it > > ends up increasing performance. > > > > This patch introduces the new MADV_COOL hint to madvise(2) > > syscall. MADV_COOL can be used by a process to mark a memory range > > as not expected to be used in the near future. The hint can help > > kernel in deciding which pages to evict early during memory > > pressure. > > I do not want to start naming fight but MADV_COOL sounds a bit > misleading. Everybody thinks his pages are cool ;). Probably MADV_COLD > or MADV_DONTNEED_PRESERVE. Thanks for the suggestion. Since I got several suggestions, Let's discuss them all at once in cover-letter. > > > Internally, it works via deactivating memory from active list to > > inactive's head so when the memory pressure happens, they will be > > reclaimed earlier than other active pages unless there is no > > access until the time. > > Could you elaborate about the decision to move to the head rather than > tail? What should happen to inactive pages? Should we move them to the > tail? Your implementation seems to ignore those completely. Why? Normally, inactive LRU could have used-once pages without any mapping to user's address space. Such pages would be better candicate to reclaim when the memory pressure happens. With deactivating only active LRU pages of the process to the head of inactive LRU, we will keep them in RAM longer than used-once pages and could have more chance to be activated once the process is resumed. > > What should happen for shared pages? In other words do we want to allow > less privileged process to control evicting of shared pages with a more > privileged one? E.g. think of all sorts of side channel attacks. Maybe > we want to do the same thing as for mincore where write access is > required. It doesn't work with shared pages(ie, page_mapcount > 1). I will add it in the description. > -- > Michal Hocko > SUSE Labs ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [RFC 1/7] mm: introduce MADV_COOL 2019-05-20 22:54 ` Minchan Kim @ 2019-05-21 6:04 ` Michal Hocko 2019-05-21 9:11 ` Minchan Kim 0 siblings, 1 reply; 13+ messages in thread From: Michal Hocko @ 2019-05-21 6:04 UTC (permalink / raw) To: Minchan Kim Cc: Andrew Morton, LKML, linux-mm, Johannes Weiner, Tim Murray, Joel Fernandes, Suren Baghdasaryan, Daniel Colascione, Shakeel Butt, Sonny Rao, Brian Geffon, linux-api On Tue 21-05-19 07:54:19, Minchan Kim wrote: > On Mon, May 20, 2019 at 10:16:21AM +0200, Michal Hocko wrote: [...] > > > Internally, it works via deactivating memory from active list to > > > inactive's head so when the memory pressure happens, they will be > > > reclaimed earlier than other active pages unless there is no > > > access until the time. > > > > Could you elaborate about the decision to move to the head rather than > > tail? What should happen to inactive pages? Should we move them to the > > tail? Your implementation seems to ignore those completely. Why? > > Normally, inactive LRU could have used-once pages without any mapping > to user's address space. Such pages would be better candicate to > reclaim when the memory pressure happens. With deactivating only > active LRU pages of the process to the head of inactive LRU, we will > keep them in RAM longer than used-once pages and could have more chance > to be activated once the process is resumed. You are making some assumptions here. You have an explicit call what is cold now you are assuming something is even colder. Is this assumption a general enough to make people depend on it? Not that we wouldn't be able to change to logic later but that will always be risky - especially in the area when somebody want to make a user space driven memory management. > > What should happen for shared pages? In other words do we want to allow > > less privileged process to control evicting of shared pages with a more > > privileged one? E.g. think of all sorts of side channel attacks. Maybe > > we want to do the same thing as for mincore where write access is > > required. > > It doesn't work with shared pages(ie, page_mapcount > 1). I will add it > in the description. OK, this is good for the starter. It makes the implementation simpler and we can add shared mappings coverage later. Although I would argue that touching only writeable mappings should be reasonably safe. -- Michal Hocko SUSE Labs ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [RFC 1/7] mm: introduce MADV_COOL 2019-05-21 6:04 ` Michal Hocko @ 2019-05-21 9:11 ` Minchan Kim 2019-05-21 10:05 ` Michal Hocko 0 siblings, 1 reply; 13+ messages in thread From: Minchan Kim @ 2019-05-21 9:11 UTC (permalink / raw) To: Michal Hocko Cc: Andrew Morton, LKML, linux-mm, Johannes Weiner, Tim Murray, Joel Fernandes, Suren Baghdasaryan, Daniel Colascione, Shakeel Butt, Sonny Rao, Brian Geffon, linux-api On Tue, May 21, 2019 at 08:04:43AM +0200, Michal Hocko wrote: > On Tue 21-05-19 07:54:19, Minchan Kim wrote: > > On Mon, May 20, 2019 at 10:16:21AM +0200, Michal Hocko wrote: > [...] > > > > Internally, it works via deactivating memory from active list to > > > > inactive's head so when the memory pressure happens, they will be > > > > reclaimed earlier than other active pages unless there is no > > > > access until the time. > > > > > > Could you elaborate about the decision to move to the head rather than > > > tail? What should happen to inactive pages? Should we move them to the > > > tail? Your implementation seems to ignore those completely. Why? > > > > Normally, inactive LRU could have used-once pages without any mapping > > to user's address space. Such pages would be better candicate to > > reclaim when the memory pressure happens. With deactivating only > > active LRU pages of the process to the head of inactive LRU, we will > > keep them in RAM longer than used-once pages and could have more chance > > to be activated once the process is resumed. > > You are making some assumptions here. You have an explicit call what is > cold now you are assuming something is even colder. Is this assumption a > general enough to make people depend on it? Not that we wouldn't be able > to change to logic later but that will always be risky - especially in > the area when somebody want to make a user space driven memory > management. Think about MADV_FREE. It moves those pages into inactive file LRU's head. See the get_scan_count which makes forceful scanning of inactive file LRU if it has enough size based on the memory pressure. The reason is it's likely to have used-once pages in inactive file LRU, generally. Those pages has been top-priority candidate to be reclaimed for a long time. Only parts I am aware of moving pages into tail of inactive LRU are places writeback is done for pages VM already decide to reclaim by LRU aging or destructive operation like invalidating but couldn't completed. It's really strong hints with no doubt. > > > > What should happen for shared pages? In other words do we want to allow > > > less privileged process to control evicting of shared pages with a more > > > privileged one? E.g. think of all sorts of side channel attacks. Maybe > > > we want to do the same thing as for mincore where write access is > > > required. > > > > It doesn't work with shared pages(ie, page_mapcount > 1). I will add it > > in the description. > > OK, this is good for the starter. It makes the implementation simpler > and we can add shared mappings coverage later. > > Although I would argue that touching only writeable mappings should be > reasonably safe. > > -- > Michal Hocko > SUSE Labs ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [RFC 1/7] mm: introduce MADV_COOL 2019-05-21 9:11 ` Minchan Kim @ 2019-05-21 10:05 ` Michal Hocko 0 siblings, 0 replies; 13+ messages in thread From: Michal Hocko @ 2019-05-21 10:05 UTC (permalink / raw) To: Minchan Kim Cc: Andrew Morton, LKML, linux-mm, Johannes Weiner, Tim Murray, Joel Fernandes, Suren Baghdasaryan, Daniel Colascione, Shakeel Butt, Sonny Rao, Brian Geffon, linux-api On Tue 21-05-19 18:11:34, Minchan Kim wrote: > On Tue, May 21, 2019 at 08:04:43AM +0200, Michal Hocko wrote: > > On Tue 21-05-19 07:54:19, Minchan Kim wrote: > > > On Mon, May 20, 2019 at 10:16:21AM +0200, Michal Hocko wrote: > > [...] > > > > > Internally, it works via deactivating memory from active list to > > > > > inactive's head so when the memory pressure happens, they will be > > > > > reclaimed earlier than other active pages unless there is no > > > > > access until the time. > > > > > > > > Could you elaborate about the decision to move to the head rather than > > > > tail? What should happen to inactive pages? Should we move them to the > > > > tail? Your implementation seems to ignore those completely. Why? > > > > > > Normally, inactive LRU could have used-once pages without any mapping > > > to user's address space. Such pages would be better candicate to > > > reclaim when the memory pressure happens. With deactivating only > > > active LRU pages of the process to the head of inactive LRU, we will > > > keep them in RAM longer than used-once pages and could have more chance > > > to be activated once the process is resumed. > > > > You are making some assumptions here. You have an explicit call what is > > cold now you are assuming something is even colder. Is this assumption a > > general enough to make people depend on it? Not that we wouldn't be able > > to change to logic later but that will always be risky - especially in > > the area when somebody want to make a user space driven memory > > management. > > Think about MADV_FREE. It moves those pages into inactive file LRU's head. > See the get_scan_count which makes forceful scanning of inactive file LRU > if it has enough size based on the memory pressure. > The reason is it's likely to have used-once pages in inactive file LRU, > generally. Those pages has been top-priority candidate to be reclaimed > for a long time. OK, fair enough. Being consistent with MADV_FREE is reasonable. I just forgot we do rotate like this there. -- Michal Hocko SUSE Labs ^ permalink raw reply [flat|nested] 13+ messages in thread
* Re: [RFC 1/7] mm: introduce MADV_COOL 2019-05-20 3:52 ` [RFC 1/7] mm: introduce MADV_COOL Minchan Kim 2019-05-20 8:16 ` Michal Hocko @ 2019-05-28 10:58 ` Minchan Kim 1 sibling, 0 replies; 13+ messages in thread From: Minchan Kim @ 2019-05-28 10:58 UTC (permalink / raw) To: Hillf Danton Cc: Andrew Morton, LKML, linux-mm, Michal Hocko, Johannes Weiner, Tim Murray, Joel Fernandes, Suren Baghdasaryan, Daniel Colascione, Shakeel Butt, Sonny Rao, Brian Geffon On Tue, May 28, 2019 at 04:53:01PM +0800, Hillf Danton wrote: > > On Mon, 20 May 2019 12:52:48 +0900 Minchan Kim wrote: > > +static int madvise_cool_pte_range(pmd_t *pmd, unsigned long addr, > > + unsigned long end, struct mm_walk *walk) > > +{ > > + pte_t *orig_pte, *pte, ptent; > > + spinlock_t *ptl; > > + struct page *page; > > + struct vm_area_struct *vma = walk->vma; > > + unsigned long next; > > + > > + next = pmd_addr_end(addr, end); > > + if (pmd_trans_huge(*pmd)) { > > + spinlock_t *ptl; > > Seems not needed with another ptl declared above. Will remove it. > > + > > + ptl = pmd_trans_huge_lock(pmd, vma); > > + if (!ptl) > > + return 0; > > + > > + if (is_huge_zero_pmd(*pmd)) > > + goto huge_unlock; > > + > > + page = pmd_page(*pmd); > > + if (page_mapcount(page) > 1) > > + goto huge_unlock; > > + > > + if (next - addr != HPAGE_PMD_SIZE) { > > + int err; > > Alternately, we deactivate thp only if the address range from userspace > is sane enough, in order to avoid complex works we have to do here. Not sure it's a good idea. That's the way we have done in MADV_FREE so want to be consistent. > > + > > + get_page(page); > > + spin_unlock(ptl); > > + lock_page(page); > > + err = split_huge_page(page); > > + unlock_page(page); > > + put_page(page); > > + if (!err) > > + goto regular_page; > > + return 0; > > + } > > + > > + pmdp_test_and_clear_young(vma, addr, pmd); > > + deactivate_page(page); > > +huge_unlock: > > + spin_unlock(ptl); > > + return 0; > > + } > > + > > + if (pmd_trans_unstable(pmd)) > > + return 0; > > + > > +regular_page: > > Take a look at pending signal? Do you have any reason to see pending signal here? I want to know what's your requirement so that what's the better place to handle it. > > > + orig_pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); > > + for (pte = orig_pte; addr < end; pte++, addr += PAGE_SIZE) { > > s/end/next/ ? Why do you think it should be next? > > + ptent = *pte; > > + > > + if (pte_none(ptent)) > > + continue; > > + > > + if (!pte_present(ptent)) > > + continue; > > + > > + page = vm_normal_page(vma, addr, ptent); > > + if (!page) > > + continue; > > + > > + if (page_mapcount(page) > 1) > > + continue; > > + > > + ptep_test_and_clear_young(vma, addr, pte); > > + deactivate_page(page); > > + } > > + > > + pte_unmap_unlock(orig_pte, ptl); > > + cond_resched(); > > + > > + return 0; > > +} > > + > > +static long madvise_cool(struct vm_area_struct *vma, > > + unsigned long start_addr, unsigned long end_addr) > > +{ > > + struct mm_struct *mm = vma->vm_mm; > > + struct mmu_gather tlb; > > + > > + if (vma->vm_flags & (VM_LOCKED|VM_HUGETLB|VM_PFNMAP)) > > + return -EINVAL; > > No service in case of VM_IO? I don't know VM_IO would have regular LRU pages but just follow normal convention for DONTNEED and FREE. Do you have anything in your mind? ^ permalink raw reply [flat|nested] 13+ messages in thread
end of thread, other threads:[~2019-05-29 5:05 UTC | newest] Thread overview: 13+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- [not found] <20190528121523.8764-1-hdanton@sina.com> 2019-05-28 12:39 ` [RFC 1/7] mm: introduce MADV_COOL Minchan Kim [not found] <20190529024033.13500-1-hdanton@sina.com> 2019-05-29 5:05 ` Michal Hocko [not found] <20190528153811.7684-1-hdanton@sina.com> 2019-05-28 16:11 ` Michal Hocko 2019-05-20 3:52 [RFC 0/7] introduce memory hinting API for external process Minchan Kim 2019-05-20 3:52 ` [RFC 1/7] mm: introduce MADV_COOL Minchan Kim 2019-05-20 8:16 ` Michal Hocko 2019-05-20 8:19 ` Michal Hocko 2019-05-20 15:08 ` Suren Baghdasaryan 2019-05-20 22:55 ` Minchan Kim 2019-05-20 22:54 ` Minchan Kim 2019-05-21 6:04 ` Michal Hocko 2019-05-21 9:11 ` Minchan Kim 2019-05-21 10:05 ` Michal Hocko 2019-05-28 10:58 ` Minchan Kim
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