d5aaad6f83
Take a signed 'long' instead of an 'unsigned long' for the number of pages to add/subtract to the total number of pages used by the MMU. This fixes a zero-extension bug on 32-bit kernels that effectively corrupts the per-cpu counter used by the shrinker. Per-cpu counters take a signed 64-bit value on both 32-bit and 64-bit kernels, whereas kvm_mod_used_mmu_pages() takes an unsigned long and thus an unsigned 32-bit value on 32-bit kernels. As a result, the value used to adjust the per-cpu counter is zero-extended (unsigned -> signed), not sign-extended (signed -> signed), and so KVM's intended -1 gets morphed to 4294967295 and effectively corrupts the counter. This was found by a staggering amount of sheer dumb luck when running kvm-unit-tests on a 32-bit KVM build. The shrinker just happened to kick in while running tests and do_shrink_slab() logged an error about trying to free a negative number of objects. The truly lucky part is that the kernel just happened to be a slightly stale build, as the shrinker no longer yells about negative objects as of commit |
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| .. | ||
| mmu_audit.c | ||
| mmu_internal.h | ||
| mmu.c | ||
| mmutrace.h | ||
| page_track.c | ||
| paging_tmpl.h | ||
| paging.h | ||
| spte.c | ||
| spte.h | ||
| tdp_iter.c | ||
| tdp_iter.h | ||
| tdp_mmu.c | ||
| tdp_mmu.h | ||