On Thu, Jan 13, 2022 at 10:03:06AM -0800, Mike Kravetz wrote: > MADV_DONTNEED is currently disabled for hugetlb mappings. This > certainly makes sense in shared file mappings as the pagecache maintains > a reference to the page and it will never be freed. However, it could > be useful to unmap and free pages in private mappings. > > The only thing preventing MADV_DONTNEED (and MADV_FREE) from working on > hugetlb mappings is a check in can_madv_lru_vma(). To allow support for > hugetlb mappings create and use a new routine madvise_dontneed_valid_vma() > that will allow hugetlb mappings. > > Signed-off-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx> I briefly tested the patch and it seems that when calling madvise(MADV_DONTNEED) with the range unaligned to hugepage size (like 4kB) triggered the following crash. Could you double check around the address range issue? [ 220.915316] ------------[ cut here ]------------ [ 220.916792] kernel BUG at mm/hugetlb.c:4946! [ 220.918519] invalid opcode: 0000 [#1] PREEMPT SMP PTI [ 220.920344] CPU: 2 PID: 1665 Comm: a.out Tainted: G E 5.17.0-rc1-220126-1543+ #31 [ 220.930536] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1.fc35 04/01/2014 [ 220.934484] RIP: 0010:__unmap_hugepage_range+0x4d6/0x580 [ 220.936443] Code: ff ff 49 c7 44 24 10 ff ff ff ff 41 80 64 24 20 83 e9 34 fd ff ff 0f 0b 49 8b 47 30 48 f7 d0 4c 85 c8 0f 84 93 fb ff ff 0f 0b <0f> 0b 48 8d 7c 24 48 83 4c 24 68 01 e8 69 b9 00 00 4c 8b 4c 24 08 [ 220.943818] RSP: 0018:ffffabe9019dfc98 EFLAGS: 00010206 [ 220.945454] RAX: 000000000000a000 RBX: ffff8a0e02253ed8 RCX: 0000000000000009 [ 220.947661] RDX: 00007f1c08000000 RSI: ffff8a0e02253ed8 RDI: ffffabe9019dfdb8 [ 220.949677] RBP: 0000000000200000 R08: 0000000000000000 R09: 00007f1c08000000 [ 220.951902] R10: 0000000000000000 R11: 0000000000000000 R12: ffffabe9019dfdb8 [ 220.954040] R13: ffffabe9019dfdb8 R14: 00007f1c08000000 R15: ffffffff9420f960 [ 220.955990] FS: 00007f1c08480540(0000) GS:ffff8a0efbc00000(0000) knlGS:0000000000000000 [ 220.958034] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 220.959517] CR2: 00007f1c0849aff8 CR3: 0000000146a52000 CR4: 00000000001506e0 [ 220.961321] Call Trace: [ 220.961945] <TASK> [ 220.962535] ? __slab_free+0xba/0x370 [ 220.963468] ? update_load_avg+0x7e/0x5f0 [ 220.964427] ? __cgroup_account_cputime+0x4c/0x70 [ 220.965596] ? page_counter_uncharge+0x1d/0x30 [ 220.966733] __unmap_hugepage_range_final+0xe/0x20 [ 220.967861] unmap_single_vma+0xc7/0xf0 [ 220.968795] zap_page_range+0xcc/0x130 [ 220.969619] ? find_vma+0x73/0x80 [ 220.970378] do_madvise.part.0+0xb65/0xea0 [ 220.971279] ? do_sigaction+0x111/0x240 [ 220.972081] __x64_sys_madvise+0x56/0x70 [ 220.972969] do_syscall_64+0x3b/0x90 [ 220.973779] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 220.974883] RIP: 0033:0x7f1c083b24eb [ 220.975632] Code: c3 48 8b 15 9f 59 0c 00 f7 d8 64 89 02 b8 ff ff ff ff eb c2 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa b8 1c 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 6d 59 0c 00 f7 d8 64 89 01 48 [ 220.979331] RSP: 002b:00007ffe7f9bc038 EFLAGS: 00000202 ORIG_RAX: 000000000000001c [ 220.980791] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f1c083b24eb [ 220.982162] RDX: 0000000000000004 RSI: 000000000000a000 RDI: 00007f1c08000000 [ 220.983550] RBP: 00007ffe7f9bc070 R08: 0000000000000000 R09: 0000000000000000 [ 220.984997] R10: 000000000040049c R11: 0000000000000202 R12: 00000000004010d0 [ 220.986399] R13: 00007ffe7f9bc150 R14: 0000000000000000 R15: 0000000000000000 [ 220.987765] </TASK> Thanks, Naoya Horiguchi
