On Wed, Sep 30, 2026 at 5:25 AM Hao Ge <[email protected]> wrote: > > Hi Suren and Andrew > > > On 2026/9/30 10:39, Suren Baghdasaryan wrote: > > On Tue, Sep 29, 2026 at 8:44 PM Andrew Morton <[email protected]> > > wrote: > >> > >> On Tue, 29 Sep 2026 16:20:07 +0800 Hao Ge <[email protected]> wrote: > >> > >>> With profiling toggled off, the overflow check in > >>> reserve_module_tags() did not run, a module could load with more > >>> tags than the page flags can address, and re-enabling profiling > >>> then silently corrupted /proc/allocinfo. On overflow the fix shuts > >>> profiling down, releases the reservation and returns -EAGAIN, and > >>> the codetag section lands as regular module data in the same load, > >>> so the module loads without profiling. > >>> > >>> Review of the earlier series by Sashiko turned up more problems. > >>> > >>> One is a race. layout_sections() and move_module() both asked > >>> codetag_needs_module_section() where a codetag section goes, and > >>> mem_profiling_support can change between the two calls, for instance > >>> when another module load overflows the tag index and shuts profiling > >>> down. move_module() then copied the codetag section to offset 0 of > >>> its regular destination and clobbered the first section placed in > >>> that region. > >>> > >>> v7 reworks where codetag sections are allocated, on a prototype by > >>> Petr Pavlu [1]. The allocation runs before layout_sections() and the > >>> placement is decided in one step, so nothing re-asks the question > >>> and the race is gone. The retry is gone too, on -EAGAIN the section > >>> is laid out as regular module data right in the same load. > >> > >> Thanks. > >> > >> Seven patches, all cc:stable. Why is a backport proposed? > >> Documentation/process/stable-kernel-rules.rst gives guidelines - does > >> this series meet them? Does Suren have thoughts? > > Thanks, I've just gone through this carefully. > > > > > I think vmalloc fix in patch#2 should be posted separately and clearly > > quialifies for backporting as if fixes issues Hao found at [1]. > > Agreed. Patch #2 was added to this patch series because > vm_module_tags_populate > suffers from the same issue. If we want to be more conservative, I'd prefer > to keep > vm_module_tags_populate as it was in V10: > https://lore.kernel.org/all/[email protected]/ > > Then we can submit a fix for __GFP_NOFAIL retry loop in __vmalloc_area_node() > as a hotfix together > with our new patch #2. While at it, we can also check if there are any > unnecessary calls to > vunmap_range family functions that can be cleaned up now that patch #2 is > applied. > > > > > > The rest are also bug fixes but their size is concerning. I'll review > > them first before advising on which ones should be backported. Some > > fixes address issues that happen very rarely and if a fix is too > > complex it might make sense to leave it be or fix it some other way > > with less churn. Please give me a couple of days to review them. With > > the upcoming LPC I'm trying to multiplex between several projects. > > Thanks, sorry for all the hassle on you folks.
You have no reasons to be sorry. It's me who is delaying the reviews. > > Thanks > Best Regards > Hao > > > > > [1] > > https://lore.kernel.org/all/[email protected]/ > > > >> > >> Also, Sashiko has been busy again: > >> > >> https://sashiko.dev/#/patchset/[email protected]
