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Wed, 25 Mar 2026 08:17:34 -0700 (PDT) MIME-Version: 1.0 References: <20260319083153.2488005-1-hao.ge@linux.dev> <20260319152808.fce61386fdf2934d7a3b0edb@linux-foundation.org> <9ef1c798-a30f-4458-9684-900136ae8b7d@linux.dev> <575e727e-cd47-41df-966a-142425aa8a8b@linux.dev> <35d274d9-ed52-4325-80fb-c374e8af3169@linux.dev> <88c6ac9d-d966-4c25-b16d-6808f9e8c43a@linux.dev> In-Reply-To: From: Suren Baghdasaryan Date: Wed, 25 Mar 2026 08:17:21 -0700 X-Gm-Features: AQROBzDHXM0k72hug5dKYc48HF06v9-ZoqQU6KMfXNongWvapnJS4zWGfaqI3-4 Message-ID: Subject: Re: [PATCH] mm/alloc_tag: clear codetag for pages allocated before page_ext initialization To: Hao Ge Cc: Andrew Morton , Kent Overstreet , linux-mm@kvack.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam12 X-Stat-Signature: 1nwnqhdoejzbo9imo368k9ry5unjgn4z X-Rspamd-Queue-Id: 786B018000D X-Rspam-User: X-HE-Tag: 1774451856-44641 X-HE-Meta: U2FsdGVkX19LS+HH+rav2kVhkVr+gDk/upxPO1ET38i2iY2mtCmsjIKPNcL1O3rzus4NDkPbfGf2CrycL6N8xAwoO60hJ+hWoEVl3wW1P45d1+d60OGJE+JqZSOCVMBMyMZXSfp+U+njwLRjklhaA9WmFJ9Li1KjPU3uGUo/KFWE6MBkqw/XcVhkFRRrI8LSajhHwk0h/4JjSCOx7RhQLsE/D++w8eI/gLK6k3vyx9pCqX8xX9BmslJZMAdV4NTVq/u+RfOi+DDdwMjmxjM2GJkXOPBc03O9YSCRqP1e5u3cN78Lcn6yw2h/gvev2bGPlnzny7yOlTEXh6vhuFdySnIT2i5eRrwug8iW7TAXJIypkueyEDiadt2WgD404TfynyETP55pmrMgRfYrqs7otsqcqw2JvsBxE34hsVP1NMgmm9La0CNvvq1S04ON2KREvxZQVNu7P2DjBl7KILEd8Y8T48uF68RcyQNYvMrzaQS/IOm8dzLsdbPe8YF2IfZPB3tqhkatnWMp2hGha5kWlmBQqbFGZ/whMZemwbakQlG1j1YhTQrNYY3JYWS9bkOhFuQt1CEBand+dnHn58182yIEU2fQFlRdsCtqvi6WJmW0N+aCN4ije8tWU5G7iD2S2DMGDHJmN5ROWSmwj1MLt3fazAJc+H21RLKBgAdjFeVX1Ffy7V1mgY4RjZx8MjXeRGVmjXCI8eEjNDYfusJ5aF5oQMtEFQsNV4e5buv6SsPg3vzRdCUKTH1VgYAxbmEVFgZ+LGP+UOzB9Ycqr/8crUPs0Ql7apOoCPjARB4+9vIX1xPNsoJhTetnBM3DLPlX90oRM5X+YRvIX641jO/MpoXdVbQkxgJWpjoi/2YqSsXHermfN/gO2VOOxjVf1HocadwC95aWC2PhlzS5misp5JNGYFRfokP0Cb462TN2Y2wa7j+iEnz1+Zze5eYhvPkHPqZq9q3S2ETG0jZyTEA 5/vjFErK CD0Box3eE4/SHLOKTa/SR1z+LSNOnAKen4Ex0uTTLVkROL0PECqEZba3//CtfXFBTjFxVEYHaZ/lnwW3LlTuvzyzJx/V+Gm2EBDws4H5ghuhih4wRIz18X62bQD2q1m13Tmi534e/dAMWF90Lqz4LxOb6nKdAGELxDBsgP091/scT7I+EL5Lo+k2T2LgzyBP3bWHuGphTcYvSV7DfYl1s9P84xxebrao/zZI+5A+ZS1EZ59fH8eeSYhuWCQ2nHmGzXrd3xm4yId5+wbRM4n19HxOhm/qkdlPf73bfAxSRnw+/ElQFURbaQ7DfctryvFqD670JzsgFV4bqpn5qxhv/HbYs90RoB9R6YxJAfu28w20bAzq/Poqftmma3mep5GgX4BP5Ub2Xb/Eo9j8eFHLwudMZeFEeLv7HgcOBxjV0s+vLlhhyFNl7l7QR0+WXINQ5pETP2n9/3YWjLMX7stUZdkXY1B/ydvJ7SxxZgKHbeayAU3Q= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Mar 25, 2026 at 4:21=E2=80=AFAM Hao Ge wrote: > > > On 2026/3/25 15:35, Suren Baghdasaryan wrote: > > On Tue, Mar 24, 2026 at 11:25=E2=80=AFPM Suren Baghdasaryan wrote: > >> On Tue, Mar 24, 2026 at 7:08=E2=80=AFPM Hao Ge wrot= e: > >>> > >>> On 2026/3/25 08:21, Suren Baghdasaryan wrote: > >>>> On Tue, Mar 24, 2026 at 2:43=E2=80=AFAM Hao Ge wr= ote: > >>>>> On 2026/3/24 06:47, Suren Baghdasaryan wrote: > >>>>>> On Mon, Mar 23, 2026 at 2:16=E2=80=AFAM Hao Ge = wrote: > >>>>>>> On 2026/3/20 10:14, Suren Baghdasaryan wrote: > >>>>>>>> On Thu, Mar 19, 2026 at 6:58=E2=80=AFPM Hao Ge wrote: > >>>>>>>>> On 2026/3/20 07:48, Suren Baghdasaryan wrote: > >>>>>>>>>> On Thu, Mar 19, 2026 at 4:44=E2=80=AFPM Suren Baghdasaryan wrote: > >>>>>>>>>>> On Thu, Mar 19, 2026 at 3:28=E2=80=AFPM Andrew Morton wrote: > >>>>>>>>>>>> On Thu, 19 Mar 2026 16:31:53 +0800 Hao Ge = wrote: > >>>>>>>>>>>> > >>>>>>>>>>>>> Due to initialization ordering, page_ext is allocated and i= nitialized > >>>>>>>>>>>>> relatively late during boot. Some pages have already been a= llocated > >>>>>>>>>>>>> and freed before page_ext becomes available, leaving their = codetag > >>>>>>>>>>>>> uninitialized. > >>>>>>>>>>> Hi Hao, > >>>>>>>>>>> Thanks for the report. > >>>>>>>>>>> Hmm. So, we are allocating pages before page_ext is initializ= ed... > >>>>>>>>>>> > >>>>>>>>>>>>> A clear example is in init_section_page_ext(): alloc_page_e= xt() calls > >>>>>>>>>>>>> kmemleak_alloc(). > >>>>>>>>>> Forgot to ask. The example you are using here is for page_ext > >>>>>>>>>> allocation itself. Do you have any other examples where page > >>>>>>>>>> allocation happens before page_ext initialization? If that's t= he only > >>>>>>>>>> place, then we might be able to fix this in a simpler way by d= oing > >>>>>>>>>> something special for alloc_page_ext(). > >>>>>>>>> Hi Suren > >>>>>>>>> > >>>>>>>>> To help illustrate the point, here's the debug log I added: > >>>>>>>>> > >>>>>>>>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c > >>>>>>>>> index 2d4b6f1a554e..ebfe636f5b07 100644 > >>>>>>>>> --- a/mm/page_alloc.c > >>>>>>>>> +++ b/mm/page_alloc.c > >>>>>>>>> @@ -1293,6 +1293,9 @@ void __pgalloc_tag_add(struct page *page,= struct > >>>>>>>>> task_struct *task, > >>>>>>>>> alloc_tag_add(&ref, task->alloc_tag, PAGE_= SIZE * nr); > >>>>>>>>> update_page_tag_ref(handle, &ref); > >>>>>>>>> put_page_tag_ref(handle); > >>>>>>>>> + } else { > >>>>>>>>> + pr_warn("__pgalloc_tag_add: get_page_tag_ref fa= iled! > >>>>>>>>> page=3D%p pfn=3D%lu nr=3D%u\n", page, page_to_pfn(page), nr); > >>>>>>>>> + dump_stack(); > >>>>>>>>> } > >>>>>>>>> } > >>>>>>>>> > >>>>>>>>> > >>>>>>>>> And I caught the following logs: > >>>>>>>>> > >>>>>>>>> [ 0.296399] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>>>>>> page=3Dffffea000400c700 pfn=3D1049372 nr=3D1 > >>>>>>>>> [ 0.296400] CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted > >>>>>>>>> 7.0.0-rc4-dirty #12 PREEMPT(lazy) > >>>>>>>>> [ 0.296402] Hardware name: Red Hat KVM, BIOS > >>>>>>>>> rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 > >>>>>>>>> [ 0.296402] Call Trace: > >>>>>>>>> [ 0.296403] > >>>>>>>>> [ 0.296403] dump_stack_lvl+0x53/0x70 > >>>>>>>>> [ 0.296405] __pgalloc_tag_add+0x3a3/0x6e0 > >>>>>>>>> [ 0.296406] ? __pfx___pgalloc_tag_add+0x10/0x10 > >>>>>>>>> [ 0.296407] ? kasan_unpoison+0x27/0x60 > >>>>>>>>> [ 0.296409] ? __kasan_unpoison_pages+0x2c/0x40 > >>>>>>>>> [ 0.296411] get_page_from_freelist+0xa54/0x1310 > >>>>>>>>> [ 0.296413] __alloc_frozen_pages_noprof+0x206/0x4c0 > >>>>>>>>> [ 0.296415] ? __pfx___alloc_frozen_pages_noprof+0x10/0x10 > >>>>>>>>> [ 0.296417] ? stack_depot_save_flags+0x3f/0x680 > >>>>>>>>> [ 0.296418] ? ___slab_alloc+0x518/0x530 > >>>>>>>>> [ 0.296420] alloc_pages_mpol+0x13a/0x3f0 > >>>>>>>>> [ 0.296421] ? __pfx_alloc_pages_mpol+0x10/0x10 > >>>>>>>>> [ 0.296423] ? _raw_spin_lock_irqsave+0x8a/0xf0 > >>>>>>>>> [ 0.296424] ? __pfx__raw_spin_lock_irqsave+0x10/0x10 > >>>>>>>>> [ 0.296426] alloc_slab_page+0xc2/0x130 > >>>>>>>>> [ 0.296427] allocate_slab+0x77/0x2c0 > >>>>>>>>> [ 0.296429] ? syscall_enter_define_fields+0x3bb/0x5f0 > >>>>>>>>> [ 0.296430] ___slab_alloc+0x125/0x530 > >>>>>>>>> [ 0.296432] ? __trace_define_field+0x252/0x3d0 > >>>>>>>>> [ 0.296433] __kmalloc_noprof+0x329/0x630 > >>>>>>>>> [ 0.296435] ? syscall_enter_define_fields+0x3bb/0x5f0 > >>>>>>>>> [ 0.296436] syscall_enter_define_fields+0x3bb/0x5f0 > >>>>>>>>> [ 0.296438] ? __pfx_syscall_enter_define_fields+0x10/0x10 > >>>>>>>>> [ 0.296440] event_define_fields+0x326/0x540 > >>>>>>>>> [ 0.296441] __trace_early_add_events+0xac/0x3c0 > >>>>>>>>> [ 0.296443] trace_event_init+0x24c/0x460 > >>>>>>>>> [ 0.296445] trace_init+0x9/0x20 > >>>>>>>>> [ 0.296446] start_kernel+0x199/0x3c0 > >>>>>>>>> [ 0.296448] x86_64_start_reservations+0x18/0x30 > >>>>>>>>> [ 0.296449] x86_64_start_kernel+0xe2/0xf0 > >>>>>>>>> [ 0.296451] common_startup_64+0x13e/0x141 > >>>>>>>>> [ 0.296453] > >>>>>>>>> > >>>>>>>>> > >>>>>>>>> [ 0.312234] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>>>>>> page=3Dffffea000400f900 pfn=3D1049572 nr=3D1 > >>>>>>>>> [ 0.312234] CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted > >>>>>>>>> 7.0.0-rc4-dirty #12 PREEMPT(lazy) > >>>>>>>>> [ 0.312236] Hardware name: Red Hat KVM, BIOS > >>>>>>>>> rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 > >>>>>>>>> [ 0.312236] Call Trace: > >>>>>>>>> [ 0.312237] > >>>>>>>>> [ 0.312237] dump_stack_lvl+0x53/0x70 > >>>>>>>>> [ 0.312239] __pgalloc_tag_add+0x3a3/0x6e0 > >>>>>>>>> [ 0.312240] ? __pfx___pgalloc_tag_add+0x10/0x10 > >>>>>>>>> [ 0.312241] ? rmqueue.constprop.0+0x4fc/0x1ce0 > >>>>>>>>> [ 0.312243] ? kasan_unpoison+0x27/0x60 > >>>>>>>>> [ 0.312244] ? __kasan_unpoison_pages+0x2c/0x40 > >>>>>>>>> [ 0.312246] get_page_from_freelist+0xa54/0x1310 > >>>>>>>>> [ 0.312248] __alloc_frozen_pages_noprof+0x206/0x4c0 > >>>>>>>>> [ 0.312250] ? __pfx___alloc_frozen_pages_noprof+0x10/0x10 > >>>>>>>>> [ 0.312253] alloc_slab_page+0x39/0x130 > >>>>>>>>> [ 0.312254] allocate_slab+0x77/0x2c0 > >>>>>>>>> [ 0.312255] ? alloc_cpumask_var_node+0xc7/0x230 > >>>>>>>>> [ 0.312257] ___slab_alloc+0x46d/0x530 > >>>>>>>>> [ 0.312259] __kmalloc_node_noprof+0x2fa/0x680 > >>>>>>>>> [ 0.312261] ? alloc_cpumask_var_node+0xc7/0x230 > >>>>>>>>> [ 0.312263] alloc_cpumask_var_node+0xc7/0x230 > >>>>>>>>> [ 0.312264] init_desc+0x141/0x6b0 > >>>>>>>>> [ 0.312266] alloc_desc+0x108/0x1b0 > >>>>>>>>> [ 0.312267] early_irq_init+0xee/0x1c0 > >>>>>>>>> [ 0.312268] ? __pfx_early_irq_init+0x10/0x10 > >>>>>>>>> [ 0.312271] start_kernel+0x1ab/0x3c0 > >>>>>>>>> [ 0.312272] x86_64_start_reservations+0x18/0x30 > >>>>>>>>> [ 0.312274] x86_64_start_kernel+0xe2/0xf0 > >>>>>>>>> [ 0.312275] common_startup_64+0x13e/0x141 > >>>>>>>>> [ 0.312277] > >>>>>>>>> > >>>>>>>>> [ 0.312834] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>>>>>> page=3Dffffea000400fc00 pfn=3D1049584 nr=3D1 > >>>>>>>>> [ 0.312835] CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted > >>>>>>>>> 7.0.0-rc4-dirty #12 PREEMPT(lazy) > >>>>>>>>> [ 0.312836] Hardware name: Red Hat KVM, BIOS > >>>>>>>>> rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 > >>>>>>>>> [ 0.312837] Call Trace: > >>>>>>>>> [ 0.312837] > >>>>>>>>> [ 0.312838] dump_stack_lvl+0x53/0x70 > >>>>>>>>> [ 0.312840] __pgalloc_tag_add+0x3a3/0x6e0 > >>>>>>>>> [ 0.312841] ? __pfx___pgalloc_tag_add+0x10/0x10 > >>>>>>>>> [ 0.312842] ? rmqueue.constprop.0+0x4fc/0x1ce0 > >>>>>>>>> [ 0.312844] ? kasan_unpoison+0x27/0x60 > >>>>>>>>> [ 0.312845] ? __kasan_unpoison_pages+0x2c/0x40 > >>>>>>>>> [ 0.312847] get_page_from_freelist+0xa54/0x1310 > >>>>>>>>> [ 0.312849] __alloc_frozen_pages_noprof+0x206/0x4c0 > >>>>>>>>> [ 0.312851] ? __pfx___alloc_frozen_pages_noprof+0x10/0x10 > >>>>>>>>> [ 0.312853] alloc_pages_mpol+0x13a/0x3f0 > >>>>>>>>> [ 0.312855] ? __pfx_alloc_pages_mpol+0x10/0x10 > >>>>>>>>> [ 0.312856] ? xas_find+0x2d8/0x450 > >>>>>>>>> [ 0.312858] ? _raw_spin_lock+0x84/0xe0 > >>>>>>>>> [ 0.312859] ? __pfx__raw_spin_lock+0x10/0x10 > >>>>>>>>> [ 0.312861] alloc_pages_noprof+0xf6/0x2b0 > >>>>>>>>> [ 0.312862] __change_page_attr+0x293/0x850 > >>>>>>>>> [ 0.312864] ? __pfx___change_page_attr+0x10/0x10 > >>>>>>>>> [ 0.312865] ? _vm_unmap_aliases+0x2d0/0x650 > >>>>>>>>> [ 0.312868] ? __pfx__vm_unmap_aliases+0x10/0x10 > >>>>>>>>> [ 0.312869] __change_page_attr_set_clr+0x16c/0x360 > >>>>>>>>> [ 0.312871] ? spp_getpage+0xbb/0x1e0 > >>>>>>>>> [ 0.312872] change_page_attr_set_clr+0x220/0x3c0 > >>>>>>>>> [ 0.312873] ? flush_tlb_one_kernel+0xf/0x30 > >>>>>>>>> [ 0.312875] ? set_pte_vaddr_p4d+0x110/0x180 > >>>>>>>>> [ 0.312877] ? __pfx_change_page_attr_set_clr+0x10/0x10 > >>>>>>>>> [ 0.312878] ? __pfx_set_pte_vaddr_p4d+0x10/0x10 > >>>>>>>>> [ 0.312881] ? __pfx_mtree_load+0x10/0x10 > >>>>>>>>> [ 0.312883] ? __pfx_mtree_load+0x10/0x10 > >>>>>>>>> [ 0.312884] ? __asan_memcpy+0x3c/0x60 > >>>>>>>>> [ 0.312886] ? set_intr_gate+0x10c/0x150 > >>>>>>>>> [ 0.312888] set_memory_ro+0x76/0xa0 > >>>>>>>>> [ 0.312889] ? __pfx_set_memory_ro+0x10/0x10 > >>>>>>>>> [ 0.312891] idt_setup_apic_and_irq_gates+0x2c1/0x390 > >>>>>>>>> > >>>>>>>>> and more. > >>>>>>>> Ok, it's not the only place. Got your point. > >>>>>>>> > >>>>>>>>> off topic - if we were to handle only alloc_page_ext() specifi= cally, > >>>>>>>>> what would be the most straightforward > >>>>>>>>> > >>>>>>>>> solution in your mind? I'd really appreciate your insight. > >>>>>>>> I was thinking if it's the only special case maybe we can handle= it > >>>>>>>> somehow differently, like we do when we allocate obj_ext vectors= for > >>>>>>>> slabs using __GFP_NO_OBJ_EXT. I haven't found a good solution ye= t but > >>>>>>>> since it's not a special case we would not be able to use it eve= n if I > >>>>>>>> came up with something... > >>>>>>>> I think your way is the most straight-forward but please try my > >>>>>>>> suggestion to see if we can avoid extra overhead. > >>>>>>>> Thanks, > >>>>>>>> Suren. > >>> Hi Suren > >>>>> Hi Suren > >>>>> > >>>>> > >>>>>> Hi Hao, > >>>>>> > >>>>>>> Hi Suren > >>>>>>> > >>>>>>> Thank you for your feedback. After re-examining this issue, > >>>>>>> > >>>>>>> I realize my previous focus was misplaced. > >>>>>>> > >>>>>>> Upon deeper consideration, I understand that this is not merely a= bug, > >>>>>>> > >>>>>>> but rather a warning that indicates a gap in our memory profiling= mechanism. > >>>>>>> > >>>>>>> Specifically, the current implementation appears to be missing me= mory > >>>>>>> allocation > >>>>>>> > >>>>>>> tracking during the period between the buddy system allocation an= d page_ext > >>>>>>> > >>>>>>> initialization. > >>>>>>> > >>>>>>> This profiling gap means we may not be capturing all relevant mem= ory > >>>>>>> allocation > >>>>>>> > >>>>>>> events during this critical transition phase. > >>>>>> Correct, this limitation exists because memory profiling relies on > >>>>>> some kernel facilities (page_ext, objj_ext) which might not be > >>>>>> initialized yet at the time of allocation. > >>>>>> > >>>>>>> My approach is to dynamically allocate codetag_ref when get_page_= tag_ref > >>>>>>> fails, > >>>>>>> > >>>>>>> and maintain a linked list to track all buddy system allocations = that > >>>>>>> occur prior to page_ext initialization. > >>>>>>> > >>>>>>> However, this introduces performance concerns: > >>>>>>> > >>>>>>> 1. Free Path Overhead: When freeing these pages, we would need to > >>>>>>> traverse the entire linked list to locate > >>>>>>> > >>>>>>> the corresponding codetag_ref, resulting in O(n) lookup = complexity > >>>>>>> per free operation. > >>>>>>> > >>>>>>> 2. Initialization Overhead: During init_page_alloc_tagging, itera= ting > >>>>>>> through the linked list to assign codetag_ref to > >>>>>>> > >>>>>>> page_ext would introduce additional traversal cost. > >>>>>>> > >>>>>>> If the number of pages is substantial, this could incur significa= nt > >>>>>>> overhead. What are your thoughts on this? I look forward to your > >>>>>>> suggestions. > >>>>>> My thinking is that these early allocations comprise a small porti= on > >>>>>> of overall memory consumed by the system. So, instead of trying to > >>>>>> record and handle them in some alternative way, we just accept tha= t > >>>>>> some counters might not be exactly accurate and ignore those early > >>>>>> allocations. See how the early slab allocations are marked with th= e > >>>>>> CODETAG_FLAG_INACCURATE flag and later reported as inaccurate. I t= hink > >>>>>> that's an acceptable alternative to introducing extra complexity a= nd > >>>>>> performance overhead. IOW, the benefits of accounting for these ea= rly > >>>>>> allocations are low compared to the effort required to account for > >>>>>> them. Unless you found a simple and performant way to do that... > >>>>> I have been exploring possible solutions to this issue over the pas= t few > >>>>> days, > >>>>> > >>>>> but so far I have not come up with a good approach. > >>>>> > >>>>> I have counted the number of memory allocations that occur earlier = than the > >>>>> > >>>>> allocation and initialization of our page_ext, and found that there= are > >>>>> actually > >>>>> > >>>>> quite a lot of them. > >>>> Interesting... I wonder it's because deferred_struct_pages defers > >>>> page_ext initialization. Can you check if setting early_page_ext > >>>> reduces or eliminates these allocations before page_ext init cases? > >>> Yes, you are correct. In my 8-core 16GB virtual machine, I used a glo= bal > >>> counter > >>> > >>> to record these allocations. With early_page_ext enabled, there were = 130 > >>> allocations > >>> > >>> before page_ext initialization. Without early_page_ext, there were 80= 2 > >>> allocations > >>> > >>> before page_ext initialization. > >>> > >>> > >>>>> Similarly, I have made the following changes and collected the > >>>>> corresponding logs. > >>>>> > >>>>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c > >>>>> index 2d4b6f1a554e..6db65b3d52d3 100644 > >>>>> --- a/mm/page_alloc.c > >>>>> +++ b/mm/page_alloc.c > >>>>> @@ -1293,6 +1293,8 @@ void __pgalloc_tag_add(struct page *page, str= uct > >>>>> task_struct *task, > >>>>> alloc_tag_add(&ref, task->alloc_tag, PAGE_SIZE *= nr); > >>>>> update_page_tag_ref(handle, &ref); > >>>>> put_page_tag_ref(handle); > >>>>> + } else{ > >>>>> + pr_warn("__pgalloc_tag_add: get_page_tag_ref failed= ! > >>>>> page=3D%p pfn=3D%lu nr=3D%u\n", page, page_to_pfn(page), nr); > >>>>> } > >>>>> } > >>>>> > >>>>> @@ -1314,6 +1316,8 @@ void __pgalloc_tag_sub(struct page *page, uns= igned > >>>>> int nr) > >>>>> alloc_tag_sub(&ref, PAGE_SIZE * nr); > >>>>> update_page_tag_ref(handle, &ref); > >>>>> put_page_tag_ref(handle); > >>>>> + } else{ > >>>>> + pr_warn("__pgalloc_tag_sub: get_page_tag_ref faile= d! > >>>>> page=3D%p pfn=3D%lu nr=3D%u\n", page, page_to_pfn(page), nr); > >>>>> } > >>>>> } > >>>>> > >>>>> [ 0.261699] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004001000 pfn=3D1048640 nr=3D2 > >>>>> [ 0.261711] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004001100 pfn=3D1048644 nr=3D4 > >>>>> [ 0.261717] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004001200 pfn=3D1048648 nr=3D4 > >>>>> [ 0.261721] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004001300 pfn=3D1048652 nr=3D4 > >>>>> [ 0.261893] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004001080 pfn=3D1048642 nr=3D2 > >>>>> [ 0.261917] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004001400 pfn=3D1048656 nr=3D4 > >>>>> [ 0.262018] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004001500 pfn=3D1048660 nr=3D2 > >>>>> [ 0.262024] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004001600 pfn=3D1048664 nr=3D8 > >>>>> [ 0.262040] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004001580 pfn=3D1048662 nr=3D1 > >>>>> [ 0.262048] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea00040015c0 pfn=3D1048663 nr=3D1 > >>>>> [ 0.262056] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004001800 pfn=3D1048672 nr=3D2 > >>>>> [ 0.262064] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004001880 pfn=3D1048674 nr=3D2 > >>>>> [ 0.262078] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004001900 pfn=3D1048676 nr=3D2 > >>>>> [ 0.262196] SLUB: HWalign=3D64, Order=3D0-3, MinObjects=3D0, CPU= s=3D8, Nodes=3D1 > >>>>> [ 0.262213] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004001980 pfn=3D1048678 nr=3D2 > >>>>> [ 0.262220] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004001a00 pfn=3D1048680 nr=3D4 > >>>>> [ 0.262246] ODEBUG: selftest passed > >>>>> [ 0.262268] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004001b00 pfn=3D1048684 nr=3D1 > >>>>> [ 0.262318] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004001b40 pfn=3D1048685 nr=3D1 > >>>>> [ 0.262368] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004001b80 pfn=3D1048686 nr=3D1 > >>>>> [ 0.262418] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004001bc0 pfn=3D1048687 nr=3D1 > >>>>> [ 0.262469] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004001c00 pfn=3D1048688 nr=3D1 > >>>>> [ 0.262519] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004001c40 pfn=3D1048689 nr=3D1 > >>>>> [ 0.262569] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004001c80 pfn=3D1048690 nr=3D1 > >>>>> [ 0.262620] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004001cc0 pfn=3D1048691 nr=3D1 > >>>>> [ 0.262670] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004001d00 pfn=3D1048692 nr=3D1 > >>>>> [ 0.262721] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004001d40 pfn=3D1048693 nr=3D1 > >>>>> [ 0.262771] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004001d80 pfn=3D1048694 nr=3D1 > >>>>> [ 0.262821] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004001dc0 pfn=3D1048695 nr=3D1 > >>>>> [ 0.262871] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004001e00 pfn=3D1048696 nr=3D1 > >>>>> [ 0.262923] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004001e40 pfn=3D1048697 nr=3D1 > >>>>> [ 0.262974] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004001e80 pfn=3D1048698 nr=3D1 > >>>>> [ 0.263024] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004001ec0 pfn=3D1048699 nr=3D1 > >>>>> [ 0.263074] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004001f00 pfn=3D1048700 nr=3D1 > >>>>> [ 0.263124] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004001f40 pfn=3D1048701 nr=3D1 > >>>>> [ 0.263174] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004001f80 pfn=3D1048702 nr=3D1 > >>>>> [ 0.263224] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004001fc0 pfn=3D1048703 nr=3D1 > >>>>> [ 0.263275] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004002000 pfn=3D1048704 nr=3D1 > >>>>> [ 0.263325] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004002040 pfn=3D1048705 nr=3D1 > >>>>> [ 0.263375] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004002080 pfn=3D1048706 nr=3D1 > >>>>> [ 0.263427] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004002400 pfn=3D1048720 nr=3D16 > >>>>> [ 0.263437] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea00040020c0 pfn=3D1048707 nr=3D1 > >>>>> [ 0.263463] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004002100 pfn=3D1048708 nr=3D1 > >>>>> [ 0.263465] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004002140 pfn=3D1048709 nr=3D1 > >>>>> [ 0.263467] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004002180 pfn=3D1048710 nr=3D1 > >>>>> [ 0.263509] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004002200 pfn=3D1048712 nr=3D4 > >>>>> [ 0.263512] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004002800 pfn=3D1048736 nr=3D8 > >>>>> [ 0.263524] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea00040021c0 pfn=3D1048711 nr=3D1 > >>>>> [ 0.263536] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004002300 pfn=3D1048716 nr=3D1 > >>>>> [ 0.263537] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004002340 pfn=3D1048717 nr=3D1 > >>>>> [ 0.263539] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004002380 pfn=3D1048718 nr=3D1 > >>>>> [ 0.263604] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004004000 pfn=3D1048832 nr=3D128 > >>>>> [ 0.263638] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004003000 pfn=3D1048768 nr=3D64 > >>>>> [ 0.263650] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004002c00 pfn=3D1048752 nr=3D16 > >>>>> [ 0.263655] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea00040023c0 pfn=3D1048719 nr=3D1 > >>>>> [ 0.270582] __pgalloc_tag_sub: get_page_tag_ref failed! > >>>>> page=3Dffffea00040023c0 pfn=3D1048719 nr=3D1 > >>>>> [ 0.270591] ftrace: allocating 52717 entries in 208 pages > >>>>> [ 0.270592] ftrace: allocated 208 pages with 3 groups > >>>>> [ 0.270620] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004002a00 pfn=3D1048744 nr=3D8 > >>>>> [ 0.270636] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea00040023c0 pfn=3D1048719 nr=3D1 > >>>>> [ 0.270643] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004006000 pfn=3D1048960 nr=3D1 > >>>>> [ 0.270649] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004006040 pfn=3D1048961 nr=3D1 > >>>>> [ 0.270658] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004007000 pfn=3D1049024 nr=3D64 > >>>>> [ 0.270659] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004006080 pfn=3D1048962 nr=3D2 > >>>>> [ 0.270722] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004006100 pfn=3D1048964 nr=3D1 > >>>>> [ 0.270730] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004006140 pfn=3D1048965 nr=3D1 > >>>>> [ 0.270738] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004006180 pfn=3D1048966 nr=3D1 > >>>>> [ 0.270777] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea00040061c0 pfn=3D1048967 nr=3D1 > >>>>> [ 0.270786] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004006200 pfn=3D1048968 nr=3D1 > >>>>> [ 0.270792] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004006240 pfn=3D1048969 nr=3D1 > >>>>> [ 0.270833] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004006300 pfn=3D1048972 nr=3D4 > >>>>> [ 0.270891] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004006280 pfn=3D1048970 nr=3D1 > >>>>> [ 0.270980] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea00040062c0 pfn=3D1048971 nr=3D1 > >>>>> [ 0.271071] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004006400 pfn=3D1048976 nr=3D1 > >>>>> [ 0.271156] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004006440 pfn=3D1048977 nr=3D1 > >>>>> [ 0.271185] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004006480 pfn=3D1048978 nr=3D2 > >>>>> [ 0.271301] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004006500 pfn=3D1048980 nr=3D1 > >>>>> [ 0.271655] Dynamic Preempt: lazy > >>>>> [ 0.271662] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004006580 pfn=3D1048982 nr=3D2 > >>>>> [ 0.271752] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004006600 pfn=3D1048984 nr=3D4 > >>>>> [ 0.271762] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004010000 pfn=3D1049600 nr=3D4 > >>>>> [ 0.271824] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004006540 pfn=3D1048981 nr=3D1 > >>>>> [ 0.271916] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004006700 pfn=3D1048988 nr=3D2 > >>>>> [ 0.271964] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004006780 pfn=3D1048990 nr=3D1 > >>>>> [ 0.272099] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea00040067c0 pfn=3D1048991 nr=3D1 > >>>>> [ 0.272138] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004006800 pfn=3D1048992 nr=3D2 > >>>>> [ 0.272144] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004006a00 pfn=3D1049000 nr=3D8 > >>>>> [ 0.272249] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004006c00 pfn=3D1049008 nr=3D8 > >>>>> [ 0.272319] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004006880 pfn=3D1048994 nr=3D2 > >>>>> [ 0.272351] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004006900 pfn=3D1048996 nr=3D4 > >>>>> [ 0.272424] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004006e00 pfn=3D1049016 nr=3D8 > >>>>> [ 0.272485] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004008000 pfn=3D1049088 nr=3D8 > >>>>> [ 0.272535] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004008200 pfn=3D1049096 nr=3D2 > >>>>> [ 0.272600] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004008400 pfn=3D1049104 nr=3D8 > >>>>> [ 0.272663] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004008300 pfn=3D1049100 nr=3D4 > >>>>> [ 0.272694] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004008280 pfn=3D1049098 nr=3D2 > >>>>> [ 0.272708] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004008600 pfn=3D1049112 nr=3D8 > >>>>> > >>>>> [ 0.272924] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004008880 pfn=3D1049122 nr=3D2 > >>>>> [ 0.272934] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004008900 pfn=3D1049124 nr=3D2 > >>>>> [ 0.272952] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004008c00 pfn=3D1049136 nr=3D4 > >>>>> [ 0.273035] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004008980 pfn=3D1049126 nr=3D2 > >>>>> [ 0.273062] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004008e00 pfn=3D1049144 nr=3D8 > >>>>> [ 0.273674] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004008d00 pfn=3D1049140 nr=3D1 > >>>>> [ 0.273884] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004008d80 pfn=3D1049142 nr=3D2 > >>>>> [ 0.273943] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004009000 pfn=3D1049152 nr=3D2 > >>>>> [ 0.274379] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004009080 pfn=3D1049154 nr=3D2 > >>>>> [ 0.274575] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004009200 pfn=3D1049160 nr=3D8 > >>>>> [ 0.274617] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004009100 pfn=3D1049156 nr=3D4 > >>>>> [ 0.274794] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004009400 pfn=3D1049168 nr=3D2 > >>>>> [ 0.274840] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004009480 pfn=3D1049170 nr=3D2 > >>>>> [ 0.275057] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004009500 pfn=3D1049172 nr=3D2 > >>>>> [ 0.275092] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004009580 pfn=3D1049174 nr=3D2 > >>>>> [ 0.275134] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004009600 pfn=3D1049176 nr=3D8 > >>>>> [ 0.275211] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004009800 pfn=3D1049184 nr=3D4 > >>>>> [ 0.275510] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004009900 pfn=3D1049188 nr=3D2 > >>>>> [ 0.275548] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004009980 pfn=3D1049190 nr=3D2 > >>>>> [ 0.275976] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004009a00 pfn=3D1049192 nr=3D8 > >>>>> [ 0.275987] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004009c00 pfn=3D1049200 nr=3D2 > >>>>> [ 0.276139] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004009c80 pfn=3D1049202 nr=3D2 > >>>>> [ 0.276152] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004008d40 pfn=3D1049141 nr=3D1 > >>>>> [ 0.276242] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004009d00 pfn=3D1049204 nr=3D1 > >>>>> [ 0.276358] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004009d40 pfn=3D1049205 nr=3D1 > >>>>> [ 0.276444] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004009d80 pfn=3D1049206 nr=3D1 > >>>>> [ 0.276526] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004009dc0 pfn=3D1049207 nr=3D1 > >>>>> [ 0.276615] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004009e00 pfn=3D1049208 nr=3D1 > >>>>> [ 0.276696] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004009e40 pfn=3D1049209 nr=3D1 > >>>>> [ 0.276792] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004009e80 pfn=3D1049210 nr=3D1 > >>>>> [ 0.276827] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004009f00 pfn=3D1049212 nr=3D2 > >>>>> [ 0.276891] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004009ec0 pfn=3D1049211 nr=3D1 > >>>>> [ 0.276999] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004009f80 pfn=3D1049214 nr=3D1 > >>>>> [ 0.277082] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea0004009fc0 pfn=3D1049215 nr=3D1 > >>>>> [ 0.277172] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea000400a000 pfn=3D1049216 nr=3D1 > >>>>> [ 0.277257] __pgalloc_tag_add: get_page_tag_ref failed! > >>>>> page=3Dffffea000400a040 pfn=3D1049217 nr=3D1 > >>>>> > >>>>> and so on. > >>>>> > >>>>> > >>>>>> I think your earlier patch can effectively detect these early > >>>>>> allocations and suppress the warnings. We should also mark these > >>>>>> allocations with CODETAG_FLAG_INACCURATE. > >>>>> Thanks to an excellent AI review, I realized there are issues with > >>>>> > >>>>> my original patch. One problem is the 256-element array; another > >>>> Yes, if there are lots of such allocations, it's not appropriate. > >>>> > >>>>> is that it involves allocation and free operations =E2=80=94 meanin= g we need > >>>>> > >>>>> to record entries at __pgalloc_tag_add and remove them at __pgalloc= _tag_sub, > >>>>> > >>>>> which introduces a noticeable overhead. I'm wondering if we can ins= tead > >>>>> set a flag > >>>>> > >>>>> bit in page flags during the early boot stage, which I'll refer to = as > >>>>> EARLY_ALLOC_FLAGS. > >>>>> > >>>>> Then, in __pgalloc_tag_sub, we first check for EARLY_ALLOC_FLAGS. I= f > >>>>> set, we clear the > >>>>> > >>>>> flag and return immediately; otherwise, we perform the actual > >>>>> subtraction of the tag count. > >>>>> > >>>>> This approach seems somewhat similar to the idea behind > >>>>> mem_profiling_compressed. > >>>> That seems doable but let's first check if we can make page_ext > >>>> initialization happen before these allocations. That would be the > >>>> ideal path. If it's not possible then we can focus on alternatives > >>>> like the one you propose. > >>> > >>> Yes, the ideal scenario would be to have page_ext initialization > >>> complete before > >>> > >>> these allocations occur. I just did a code walkthrough and found that > >>> this resembles > >>> > >>> the FLATMEM implementation approach - FLATMEM allocates page_ext befo= re > >>> the buddy > >>> > >>> system initialization, so it doesn't seem to encounter the issue we'r= e > >>> facing now. > >>> > >>> https://elixir.bootlin.com/linux/v7.0-rc5/source/mm/mm_init.c#L2707 > >> Yes, page_ext_init_flatmem() looks like an interesting option and it > >> would not work with sparsemem. TBH I would prefer to find a simple > >> solution that can identify early init allocations, mark them inaccuate > >> and suppress the warning rather than introduce some complex mechanism > >> to account for them which would work only is some cases (flatmem). > >> With your original approach I think the only real issue is the size of > >> the array that might be too small. The other issue you mentioned about > >> allocated page being freed and then re-allocated after page_ext is > >> inialized but before clear_page_tag_ref() is called is not really a > >> problem. Yes, we will lose that counter's value but it's similar to > >> other early allocations which we just treat as inaccurate. We can also > >> minimize the possibility of this happening by moving > >> clear_page_tag_ref() into init_page_alloc_tagging(). > >> > >> I don't like the pageflag option you mentioned because it adds an > >> extra condition check into __pgalloc_tag_sub() which will be executed > >> even after the init stage is over. > >> I'll look into this some more tomorrow as it's quite late now. > > > Hi Suren > > > > Just though of something. Are all these pages allocated by slab? If > > so, I think slab does not use page->lru (need to double-check) and we > > could add all these pages allocated during early init into a list and > > then set their page_ext reference to CODETAG_EMPTY in > > init_page_alloc_tagging(). > > Got your point. > > > There will indeed be some non-SLAB memory allocations here, such as the > following: > > > CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted > 7.0.0-rc4-00001-g6392c3a6119e-dirty #31 PREEMPT(lazy) > [ 0.326607] Hardware name: Red Hat KVM, BIOS > rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 > [ 0.326608] Call Trace: > [ 0.326608] > [ 0.326609] dump_stack_lvl+0x53/0x70 > [ 0.326611] __pgalloc_tag_add+0x407/0x700 > [ 0.326616] get_page_from_freelist+0xa54/0x1310 > [ 0.326618] __alloc_frozen_pages_noprof+0x206/0x4c0 > [ 0.326623] alloc_pages_mpol+0x13a/0x3f0 > [ 0.326627] alloc_pages_noprof+0xf6/0x2b0 > [ 0.326628] __pmd_alloc+0x743/0x9c0 > [ 0.326630] vmap_range_noflush+0xac0/0x10a0 > [ 0.326637] ioremap_page_range+0x17c/0x250 > [ 0.326639] __ioremap_caller+0x437/0x5c0 > [ 0.326645] acpi_os_map_iomem+0x4c0/0x660 > [ 0.326647] acpi_tb_verify_temp_table+0x1c0/0x580 > [ 0.326649] acpi_reallocate_root_table+0x2ad/0x460 > [ 0.326655] acpi_early_init+0x111/0x460 > [ 0.326657] start_kernel+0x271/0x3c0 > [ 0.326659] x86_64_start_reservations+0x18/0x30 > [ 0.326660] x86_64_start_kernel+0xe2/0xf0 > [ 0.326662] common_startup_64+0x13e/0x141 > [ 0.326663] > > CPU: 0 UID: 0 PID: 2 Comm: kthreadd Not tainted > 7.0.0-rc4-00001-g6392c3a6119e-dirty #31 PREEMPT(lazy) > [ 0.329167] Hardware name: Red Hat KVM, BIOS > rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 > [ 0.329167] Call Trace: > [ 0.329167] > [ 0.329167] dump_stack_lvl+0x53/0x70 > [ 0.329167] __pgalloc_tag_add+0x407/0x700 > [ 0.329167] get_page_from_freelist+0xa54/0x1310 > [ 0.329167] __alloc_frozen_pages_noprof+0x206/0x4c0 > [ 0.329167] __alloc_pages_noprof+0x10/0x1b0 > [ 0.329167] dup_task_struct+0x163/0x8c0 > [ 0.329167] copy_process+0x390/0x4a70 > [ 0.329167] kernel_clone+0xe1/0x830 > [ 0.329167] kernel_thread+0xcb/0x110 > [ 0.329167] kthreadd+0x8a2/0xc60 > [ 0.329167] ret_from_fork+0x551/0x720 > [ 0.329167] ret_from_fork_asm+0x1a/0x30 > [ 0.329167] > > CPU: 0 UID: 0 PID: 2 Comm: kthreadd Not tainted > 7.0.0-rc4-00001-g6392c3a6119e-dirty #31 PREEMPT(lazy) > [ 0.329167] Hardware name: Red Hat KVM, BIOS > rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 > [ 0.329167] Call Trace: > [ 0.329167] > [ 0.329167] dump_stack_lvl+0x53/0x70 > [ 0.329167] __pgalloc_tag_add+0x407/0x700 > [ 0.329167] get_page_from_freelist+0xa54/0x1310 > [ 0.329167] __alloc_frozen_pages_noprof+0x206/0x4c0 > [ 0.329167] __alloc_pages_noprof+0x10/0x1b0 > [ 0.329167] dup_task_struct+0x163/0x8c0 > [ 0.329167] copy_process+0x390/0x4a70 > [ 0.329167] kernel_clone+0xe1/0x830 > [ 0.329167] kernel_thread+0xcb/0x110 > [ 0.329167] kthreadd+0x8a2/0xc60 > [ 0.329167] ret_from_fork+0x551/0x720 > [ 0.329167] ret_from_fork_asm+0x1a/0x30 > [ 0.329167] > > CPU: 4 UID: 0 PID: 1 Comm: swapper/0 Not tainted > 7.0.0-rc4-00001-g6392c3a6119e-dirty #31 PREEMPT(lazy) > [ 0.434265] Hardware name: Red Hat KVM, BIOS > rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 > [ 0.434266] Call Trace: > [ 0.434266] > [ 0.434266] dump_stack_lvl+0x53/0x70 > [ 0.434268] __pgalloc_tag_add+0x407/0x700 > [ 0.434272] get_page_from_freelist+0xa54/0x1310 > [ 0.434274] __alloc_frozen_pages_noprof+0x206/0x4c0 > [ 0.434279] alloc_pages_exact_nid_noprof+0x10f/0x380 > [ 0.434283] init_section_page_ext+0x167/0x370 > [ 0.434284] page_ext_init+0x451/0x620 > [ 0.434287] page_alloc_init_late+0x553/0x630 > [ 0.434290] kernel_init_freeable+0x7be/0xd30 > [ 0.434294] kernel_init+0x1f/0x1f0 > [ 0.434295] ret_from_fork+0x551/0x720 > [ 0.434301] ret_from_fork_asm+0x1a/0x30 > [ 0.434303] > > CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted > 7.0.0-rc4-00001-g6392c3a6119e-dirty #31 PREEMPT(lazy) > [ 0.346712] Hardware name: Red Hat KVM, BIOS > rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 > [ 0.346713] Call Trace: > [ 0.346713] > [ 0.346714] dump_stack_lvl+0x53/0x70 > [ 0.346715] __pgalloc_tag_add+0x407/0x700 > [ 0.346720] get_page_from_freelist+0xa54/0x1310 > [ 0.346723] __alloc_frozen_pages_noprof+0x206/0x4c0 > [ 0.346729] __alloc_pages_noprof+0x10/0x1b0 > [ 0.346731] alloc_cpu_data+0x96/0x210 > [ 0.346732] rb_allocate_cpu_buffer+0xb93/0x1500 > [ 0.346739] trace_rb_cpu_prepare+0x21a/0x4f0 > [ 0.346753] cpuhp_invoke_callback+0x6db/0x14b0 > [ 0.346755] __cpuhp_invoke_callback_range+0xde/0x1d0 > [ 0.346759] _cpu_up+0x395/0x880 > [ 0.346761] cpu_up+0x1bb/0x210 > [ 0.346762] cpuhp_bringup_mask+0xd2/0x150 > [ 0.346763] bringup_nonboot_cpus+0x12b/0x170 > [ 0.346764] smp_init+0x2f/0x100 > [ 0.346766] kernel_init_freeable+0x7a5/0xd30 > [ 0.346769] kernel_init+0x1f/0x1f0 > [ 0.346771] ret_from_fork+0x551/0x720 > [ 0.346776] ret_from_fork_asm+0x1a/0x30 > [ 0.346778] > > and so on... > > > In fact, I previously conducted extensive and prolonged stress testing > > on memory profiling. After our efforts to address several WARN cases, > > one remaining scenario we are addressing is the warning triggered during > > early slab cache reclaim =E2=80=94 which is precisely the situation we ar= e currently > > encountering (although I cannot guarantee that all edge cases have been > > covered by our stress testing). During the stress testing process, this > warning > > did indeed manifest. However, the current environment triggers KASAN slab > > cache reclaim earlier than anticipated. > > > Although the memory allocated prior to page_ext initialization has a > relatively low probability of > > being released in subsequent operations (at least we have not > encountered such cases up to now), > > I remain uncertain whether there are any overlooked edge cases when > considering only slab-backed pages. Ok, I guess specialized solution for slab would not work then. I want to check on my side and understand how the number of these early allocation scales. Is it higher for bigger machines or stays constant. If the latter I think your original simple solution with some fixups can still work. I'll need to instrument my code to capture these early allocations and see where they originate. If you have a patch already doing that it would help speed it up for me. Thanks, Suren. > > > Thanks > Hao > > >> Thanks, > >> Suren. > >> > >>> However, I'm not entirely certain whether SPARSEMEM can guarantee the > >>> same behavior. > >>> > >>> > >>>>> I would appreciate your valuable feedback and any better suggestion= s you > >>>>> might have. > >>>> Thanks for pursuing this! I'll help in any way I can. > >>>> Suren. > >>> Thank you so much for your patient guidance and assistance. > >>> > >>> I truly appreciate your willingness to share your knowledge and insig= hts. > >>> > >>> Thanks, > >>> Hao > >>> > >>>>> Thanks > >>>>> > >>>>> Hao > >>>>> > >>>>>> Thanks, > >>>>>> Suren. > >>>>>> > >>>>>>> Thanks > >>>>>>> > >>>>>>> Hao > >>>>>>> > >>>>>>>>> Thanks. > >>>>>>>>> > >>>>>>>>> > >>>>>>>>>>>>> If the slab cache has no free objects, it falls back > >>>>>>>>>>>>> to the buddy allocator to allocate memory. However, at this= point page_ext > >>>>>>>>>>>>> is not yet fully initialized, so these newly allocated page= s have no > >>>>>>>>>>>>> codetag set. These pages may later be reclaimed by KASAN,wh= ich causes > >>>>>>>>>>>>> the warning to trigger when they are freed because their co= detag ref is > >>>>>>>>>>>>> still empty. > >>>>>>>>>>>>> > >>>>>>>>>>>>> Use a global array to track pages allocated before page_ext= is fully > >>>>>>>>>>>>> initialized, similar to how kmemleak tracks early allocatio= ns. > >>>>>>>>>>>>> When page_ext initialization completes, set their codetag > >>>>>>>>>>>>> to empty to avoid warnings when they are freed later. > >>>>>>>>>>>>> > >>>>>>>>>>>>> ... > >>>>>>>>>>>>> > >>>>>>>>>>>>> --- a/include/linux/alloc_tag.h > >>>>>>>>>>>>> +++ b/include/linux/alloc_tag.h > >>>>>>>>>>>>> @@ -74,6 +74,9 @@ static inline void set_codetag_empty(unio= n codetag_ref *ref) > >>>>>>>>>>>>> > >>>>>>>>>>>>> #ifdef CONFIG_MEM_ALLOC_PROFILING > >>>>>>>>>>>>> > >>>>>>>>>>>>> +bool mem_profiling_is_available(void); > >>>>>>>>>>>>> +void alloc_tag_add_early_pfn(unsigned long pfn); > >>>>>>>>>>>>> + > >>>>>>>>>>>>> #define ALLOC_TAG_SECTION_NAME "alloc_tags" > >>>>>>>>>>>>> > >>>>>>>>>>>>> struct codetag_bytes { > >>>>>>>>>>>>> diff --git a/lib/alloc_tag.c b/lib/alloc_tag.c > >>>>>>>>>>>>> index 58991ab09d84..a5bf4e72c154 100644 > >>>>>>>>>>>>> --- a/lib/alloc_tag.c > >>>>>>>>>>>>> +++ b/lib/alloc_tag.c > >>>>>>>>>>>>> @@ -6,6 +6,7 @@ > >>>>>>>>>>>>> #include > >>>>>>>>>>>>> #include > >>>>>>>>>>>>> #include > >>>>>>>>>>>>> +#include > >>>>>>>>>>>>> #include > >>>>>>>>>>>>> #include > >>>>>>>>>>>>> #include > >>>>>>>>>>>>> @@ -26,6 +27,82 @@ static bool mem_profiling_support; > >>>>>>>>>>>>> > >>>>>>>>>>>>> static struct codetag_type *alloc_tag_cttype; > >>>>>>>>>>>>> > >>>>>>>>>>>>> +/* > >>>>>>>>>>>>> + * State of the alloc_tag > >>>>>>>>>>>>> + * > >>>>>>>>>>>>> + * This is used to describe the states of the alloc_tag du= ring bootup. > >>>>>>>>>>>>> + * > >>>>>>>>>>>>> + * When we need to allocate page_ext to store codetag, we = face an > >>>>>>>>>>>>> + * initialization timing problem: > >>>>>>>>>>>>> + * > >>>>>>>>>>>>> + * Due to initialization order, pages may be allocated via= buddy system > >>>>>>>>>>>>> + * before page_ext is fully allocated and initialized. Alt= hough these > >>>>>>>>>>>>> + * pages call the allocation hooks, the codetag will not b= e set because > >>>>>>>>>>>>> + * page_ext is not yet available. > >>>>>>>>>>>>> + * > >>>>>>>>>>>>> + * When these pages are later free to the buddy system, it= triggers > >>>>>>>>>>>>> + * warnings because their codetag is actually empty if > >>>>>>>>>>>>> + * CONFIG_MEM_ALLOC_PROFILING_DEBUG is enabled. > >>>>>>>>>>>>> + * > >>>>>>>>>>>>> + * Additionally, in this situation, we cannot record detai= led allocation > >>>>>>>>>>>>> + * information for these pages. > >>>>>>>>>>>>> + */ > >>>>>>>>>>>>> +enum mem_profiling_state { > >>>>>>>>>>>>> + DOWN, /* No mem_profiling functiona= lity yet */ > >>>>>>>>>>>>> + UP /* Everything is working */ > >>>>>>>>>>>>> +}; > >>>>>>>>>>>>> + > >>>>>>>>>>>>> +static enum mem_profiling_state mem_profiling_state =3D DO= WN; > >>>>>>>>>>>>> + > >>>>>>>>>>>>> +bool mem_profiling_is_available(void) > >>>>>>>>>>>>> +{ > >>>>>>>>>>>>> + return mem_profiling_state =3D=3D UP; > >>>>>>>>>>>>> +} > >>>>>>>>>>>>> + > >>>>>>>>>>>>> +#ifdef CONFIG_MEM_ALLOC_PROFILING_DEBUG > >>>>>>>>>>>>> + > >>>>>>>>>>>>> +#define EARLY_ALLOC_PFN_MAX 256 > >>>>>>>>>>>>> + > >>>>>>>>>>>>> +static unsigned long early_pfns[EARLY_ALLOC_PFN_MAX]; > >>>>>>>>>>>> It's unfortunate that this isn't __initdata. > >>>>>>>>>>>> > >>>>>>>>>>>>> +static unsigned int early_pfn_count; > >>>>>>>>>>>>> +static DEFINE_SPINLOCK(early_pfn_lock); > >>>>>>>>>>>>> + > >>>>>>>>>>>>> > >>>>>>>>>>>>> ... > >>>>>>>>>>>>> > >>>>>>>>>>>>> --- a/mm/page_alloc.c > >>>>>>>>>>>>> +++ b/mm/page_alloc.c > >>>>>>>>>>>>> @@ -1293,6 +1293,13 @@ void __pgalloc_tag_add(struct page *= page, struct task_struct *task, > >>>>>>>>>>>>> alloc_tag_add(&ref, task->alloc_tag, PAG= E_SIZE * nr); > >>>>>>>>>>>>> update_page_tag_ref(handle, &ref); > >>>>>>>>>>>>> put_page_tag_ref(handle); > >>>>>>>>>>>>> + } else { > >>>>>>>>>>> This branch can be marked as "unlikely". > >>>>>>>>>>> > >>>>>>>>>>>>> + /* > >>>>>>>>>>>>> + * page_ext is not available yet, record the = pfn so we can > >>>>>>>>>>>>> + * clear the tag ref later when page_ext is i= nitialized. > >>>>>>>>>>>>> + */ > >>>>>>>>>>>>> + if (!mem_profiling_is_available()) > >>>>>>>>>>>>> + alloc_tag_add_early_pfn(page_to_pfn(p= age)); > >>>>>>>>>>>>> } > >>>>>>>>>>>>> } > >>>>>>>>>>>> All because of this, I believe. Is this fixable? > >>>>>>>>>>>> > >>>>>>>>>>>> If we take that `else', we know we're running in __init code= , yes? I > >>>>>>>>>>>> don't see how `__init pgalloc_tag_add_early()' could be made= to work. > >>>>>>>>>>>> hrm. Something clever, please. > >>>>>>>>>>> We can have a pointer to a function that is initialized to po= int to > >>>>>>>>>>> alloc_tag_add_early_pfn, which is defined as __init and uses > >>>>>>>>>>> early_pfns which now can be defined as __initdata. After > >>>>>>>>>>> clear_early_alloc_pfn_tag_refs() is done we reset that pointe= r to > >>>>>>>>>>> NULL. __pgalloc_tag_add() instead of calling alloc_tag_add_ea= rly_pfn() > >>>>>>>>>>> directly checks that pointer and if it's not NULL then calls = the > >>>>>>>>>>> function that it points to. This way __pgalloc_tag_add() whic= h is not > >>>>>>>>>>> an __init function will be invoking alloc_tag_add_early_pfn()= __init > >>>>>>>>>>> function only until we are done with initialization. I haven'= t tried > >>>>>>>>>>> this but I think that should work. This also eliminates the n= eed for > >>>>>>>>>>> mem_profiling_state variable since we can use this function p= ointer > >>>>>>>>>>> instead. > >>>>>>>>>>> > >>>>>>>>>>>