linux-kernel - Calls to do_swap_page() from handle_pte_fault() on a system where swap is not configured

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Message-ID: <CAEJW1wECyPh-wbgnnoOGY460ido=U2A3rPhF1FQAv7txed1-Rw@mail.gmail.com>
Date: Wed, 3 Dec 2025 13:11:24 +0530
From: Jayaraj Rajappan <jayarajpr@...il.com>
To: linux-mm@...ck.org
Cc: linux-kernel@...r.kernel.org
Subject: Calls to do_swap_page() from handle_pte_fault() on a system where
 swap is not configured

Hi,

On a system where swap is not configured, profiling using Linux "perf"
tool shows that do_swap_page() gets called from handle_pte_fault().
Kernel version is 5.14.0. HugePages are disabled on the system. Trying
to understand what could cause do_swap_page() to be called when there
is no swap configured on the system.

// kernel version
# uname -a
Linux houdini 5.14.0-570.17.1.el9_6.x86_64 #1 SMP PREEMPT_DYNAMIC Fri
May 23 22:47:01 UTC 2025 x86_64 x86_64 x86_64 GNU/Linux

// no swap device configured
# swapon --show
#

// dynamic tracepoint event configured on do_swap_page()
# perf list | grep do_swap_page
  probe:do_swap_page                                 [Tracepoint event]

  // couple of samples profiled via "perf" tool
  hbatch-bin    7301 [012]  7041.023668: probe:do_swap_page: (ffffffff89dae350)
        ffffffff89dae351 do_swap_page+0x1 ([kernel.kallsyms])
        ffffffff89db34ae __handle_mm_fault+0x2fe ([kernel.kallsyms])
        ffffffff89db38f9 handle_mm_fault+0xe9 ([kernel.kallsyms])
        ffffffff89a90ab4 do_user_addr_fault+0x154 ([kernel.kallsyms])
        ffffffff8a723d72 exc_page_fault+0x62 ([kernel.kallsyms])
        ffffffff8a800bb2 asm_exc_page_fault+0x22 ([kernel.kallsyms])
            7f6cca147faf UT_SparseMatrixELLT<float, false,
false>::multVecAndDotInternalPartial(UT_VectorT<float> const&,
UT_VectorT<float>&, double*, UT_JobInf>
                 2715da7 [unknown] ([unknown])

hbatch-bin    7247 [000]  7185.407376: probe:do_swap_page: (ffffffff89dae350)
        ffffffff89dae351 do_swap_page+0x1 ([kernel.kallsyms])
        ffffffff89db34ae __handle_mm_fault+0x2fe ([kernel.kallsyms])
        ffffffff89db38f9 handle_mm_fault+0xe9 ([kernel.kallsyms])
        ffffffff89a90ab4 do_user_addr_fault+0x154 ([kernel.kallsyms])
        ffffffff8a723d72 exc_page_fault+0x62 ([kernel.kallsyms])
        ffffffff8a800bb2 asm_exc_page_fault+0x22 ([kernel.kallsyms])
            7f6cb11b5c80 UT_PageArray<void, -1l, true, false, 10l,
long>::clearAndDestroy()+0x0
(/opt/hfs21.0.440/dsolib/libHoudiniGEO.so)
            7f6c8a357fc0 [unknown] ([unknown])
            7f6cb1140a30 GA_ATINumeric::~GA_ATINumeric()+0x0
(/opt/hfs21.0.440/dsolib/libHoudiniGEO.so)
        8310c08348fd8948 [unknown] ([unknown])

Regards,
Jayaraj