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From: Hao Ge In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Stat-Signature: c5kd3q8uosmor36nd9ysteqi7u67ddtm X-Rspamd-Queue-Id: 015D810000D X-Rspamd-Server: rspam11 X-HE-Tag: 1724600898-212244 X-HE-Meta: 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 P6AGv8UL B4N+OzGvrR0ZFz+L4mikB6xreQ4/k1PdwDxsdTdWyyhRzJ4t+qSlicqWFmgAwpeHsIxz8k1Xqkjh6RDsC5yT6qEX11bhTnFggrxJupW8QLDfQVBDpUuvcxj9yR2ahEErL+uGhGj5A56OBAE23187nAufVGGuK88MOj1Ijoa4+rNdFjlesc5ebNHPX1UBmFPIdvnNLvmSL7ZSOOON2Zj5ASqFpHyNZZEFuVl6asF+GhZ/a/n9gAsj6p2TOs/neSG0ARrr43x0inXskRyEha+lhl6QbRoTlLb/eY2ZWavK6k0aEs1+xo2Y8uisWEQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi Suren Thank you for reviewing this patch and for your suggestions. The description looks clearer now. I will revise it based on your suggestions and send out version 2. Best regards Hao On 8/24/24 00:39, Suren Baghdasaryan wrote: > On Thu, Aug 22, 2024 at 11:21 PM Hao Ge wrote: >> From: Hao Ge >> >> The PG_hwpoison page will be caught and isolated on the entrance to >> the free buddy page pool. >> >> But for poisoned pages which software injected errors, >> we can reclaim it through unpoison_memory. >> >> So mark codetags for it as empty,just like when a page >> is first added to the buddy system. >> >> It was detected by [1] and the following WARN occurred: > Hi Hao, > Thanks for fixing this. I find this description a bit unclear. How > about something like this: > > When PG_hwpoison pages are freed, they are treated differently in > free_pages_prepare() and instead of being released they are isolated. > Page allocation tag counters are decremented at this point since the > page is considered not in use. Later on when such pages are released > by unpoison_memory(), the allocation tag counters will be decremented > again and the following warning gets reported: > >> [ 113.930443][ T3282] ------------[ cut here ]------------ >> [ 113.931105][ T3282] alloc_tag was not set >> [ 113.931576][ T3282] WARNING: CPU: 2 PID: 3282 at ./include/linux/alloc_tag.h:130 pgalloc_tag_sub.part.66+0x154/0x164 >> [ 113.932866][ T3282] Modules linked in: hwpoison_inject fuse ip6t_rpfilter ip6t_REJECT nf_reject_ipv6 ipt_REJECT nf_reject_ipv4 xt_conntrack ebtable_nat ebtable_broute ip6table_nat ip6table_man4 >> [ 113.941638][ T3282] CPU: 2 UID: 0 PID: 3282 Comm: madvise11 Kdump: loaded Tainted: G W 6.11.0-rc4-dirty #18 >> [ 113.943003][ T3282] Tainted: [W]=WARN >> [ 113.943453][ T3282] Hardware name: QEMU KVM Virtual Machine, BIOS unknown 2/2/2022 >> [ 113.944378][ T3282] pstate: 40400005 (nZcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) >> [ 113.945319][ T3282] pc : pgalloc_tag_sub.part.66+0x154/0x164 >> [ 113.946016][ T3282] lr : pgalloc_tag_sub.part.66+0x154/0x164 >> [ 113.946706][ T3282] sp : ffff800087093a10 >> [ 113.947197][ T3282] x29: ffff800087093a10 x28: ffff0000d7a9d400 x27: ffff80008249f0a0 >> [ 113.948165][ T3282] x26: 0000000000000000 x25: ffff80008249f2b0 x24: 0000000000000000 >> [ 113.949134][ T3282] x23: 0000000000000001 x22: 0000000000000001 x21: 0000000000000000 >> [ 113.950597][ T3282] x20: ffff0000c08fcad8 x19: ffff80008251e000 x18: ffffffffffffffff >> [ 113.952207][ T3282] x17: 0000000000000000 x16: 0000000000000000 x15: ffff800081746210 >> [ 113.953161][ T3282] x14: 0000000000000000 x13: 205d323832335420 x12: 5b5d353031313339 >> [ 113.954120][ T3282] x11: ffff800087093500 x10: 000000000000005d x9 : 00000000ffffffd0 >> [ 113.955078][ T3282] x8 : 7f7f7f7f7f7f7f7f x7 : ffff80008236ba90 x6 : c0000000ffff7fff >> [ 113.956036][ T3282] x5 : ffff000b34bf4dc8 x4 : ffff8000820aba90 x3 : 0000000000000001 >> [ 113.956994][ T3282] x2 : ffff800ab320f000 x1 : 841d1e35ac932e00 x0 : 0000000000000000 >> [ 113.957962][ T3282] Call trace: >> [ 113.958350][ T3282] pgalloc_tag_sub.part.66+0x154/0x164 >> [ 113.959000][ T3282] pgalloc_tag_sub+0x14/0x1c >> [ 113.959539][ T3282] free_unref_page+0xf4/0x4b8 >> [ 113.960096][ T3282] __folio_put+0xd4/0x120 >> [ 113.960614][ T3282] folio_put+0x24/0x50 >> [ 113.961103][ T3282] unpoison_memory+0x4f0/0x5b0 >> [ 113.961678][ T3282] hwpoison_unpoison+0x30/0x48 [hwpoison_inject] >> [ 113.962436][ T3282] simple_attr_write_xsigned.isra.34+0xec/0x1cc >> [ 113.963183][ T3282] simple_attr_write+0x38/0x48 >> [ 113.963750][ T3282] debugfs_attr_write+0x54/0x80 >> [ 113.964330][ T3282] full_proxy_write+0x68/0x98 >> [ 113.964880][ T3282] vfs_write+0xdc/0x4d0 >> [ 113.965372][ T3282] ksys_write+0x78/0x100 >> [ 113.965875][ T3282] __arm64_sys_write+0x24/0x30 >> [ 113.966440][ T3282] invoke_syscall+0x7c/0x104 >> [ 113.966984][ T3282] el0_svc_common.constprop.1+0x88/0x104 >> [ 113.967652][ T3282] do_el0_svc+0x2c/0x38 >> [ 113.968893][ T3282] el0_svc+0x3c/0x1b8 >> [ 113.969379][ T3282] el0t_64_sync_handler+0x98/0xbc >> [ 113.969980][ T3282] el0t_64_sync+0x19c/0x1a0 >> [ 113.970511][ T3282] ---[ end trace 0000000000000000 ]--- >> >> Link [1]: https://github.com/linux-test-project/ltp/blob/master/testcases/kernel/syscalls/madvise/madvise11.c > To fix this, clear the page tag reference after the page got isolated > and accounted for. > >> Fixes: a8fc28dad6d5 ("alloc_tag: introduce clear_page_tag_ref() helper function") > This would be more appropriate: > Fixes: d224eb0287fb ("codetag: debug: mark codetags for reserved pages > as empty") > >> Cc: stable@vger.kernel.org # v6.10 >> Signed-off-by: Hao Ge >> --- >> mm/page_alloc.c | 8 ++++++++ >> 1 file changed, 8 insertions(+) >> >> diff --git a/mm/page_alloc.c b/mm/page_alloc.c >> index c565de8f48e9..7ccd2157d092 100644 >> --- a/mm/page_alloc.c >> +++ b/mm/page_alloc.c >> @@ -1054,6 +1054,14 @@ __always_inline bool free_pages_prepare(struct page *page, >> reset_page_owner(page, order); >> page_table_check_free(page, order); >> pgalloc_tag_sub(page, 1 << order); >> + >> + /* >> + * For poisoned pages which software injected errors, > Not sure what you mean by "which software injected errors". Maybe it's > a typo and should be "with software injected errors"? > >> + * we can reclaim it through unpoison_memory. >> + * so mark codetags for it as empty, >> + * just like when a page is first added to the buddy system. >> + */ > I think you can simply say here that: > /* > * The page is isolated and accounted for. Mark the codetag as empty to avoid > * accounting error when the page is freed by unpoison_memory(). > */ > >> + clear_page_tag_ref(page); >> return false; >> } >> >> -- >> 2.25.1 >>